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  • Parsing a string, Grammar file.

    - by defn
    How would I separate the below string into its parts. What I need to separate is each < Word including the angle brackets from the rest of the string. So in the below case I would end up with several strings 1. "I have to break up with you because " 2. "< reason " (without the spaces) 3. " . But Let's still " 4. "< disclaimer " 5. " ." I have to break up with you because <reason> . But let's still <disclaimer> . below is what I currently have (its ugly...) boolean complete = false; int begin = 0; int end = 0; while (complete == false) { if (s.charAt(end) == '<'){ stack.add(new Terminal(s.substring(begin, end))); begin = end; } else if (s.charAt(end) == '>') { stack.add(new NonTerminal(s.substring(begin, end))); begin = end; end++; } else if (end == s.length()){ if (isTerminal(getSubstring(s, begin, end))){ stack.add(new Terminal(s.substring(begin, end))); } else { stack.add(new NonTerminal(s.substring(begin, end))); } complete = true; } end++;

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  • Publishing my Website to my Local Disk Causes Exceptions to show Paths including my Local Disk

    - by coffeeaddict
    I've published my website many times. But didn't think about this though until I came across this issue. So I decided to publish my WAP project to a local folder on my C drive first. Then used FTP to upload it to my shared host on discountasp.net. I noticed during runtime that the stack trace was referencing that local folder still and erroring out. Anyone know what config settings are affected when publishing? Obviously something is still pointing to my local C drive and I've searched my entire solution and don't see why. Here's the runtime error I get when my code tries to run in discountasp.net's web server Cannot write into the public directory - check permissions Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: ScrewTurn.Wiki.PluginFramework.InvalidConfigurationException: Cannot write into the public directory - check permissions Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [InvalidConfigurationException: Cannot write into the public directory - check permissions] ScrewTurn.Wiki.SettingsStorageProvider.Init(IHostV30 host, String config) in C:\www\Wiki\Screwturn3_0_2_509\Core\SettingsStorageProvider.cs:90 ScrewTurn.Wiki.StartupTools.Startup() in C:\www\Wiki\Screwturn3_0_2_509\Core\StartupTools.cs:69 ScrewTurn.Wiki.Global.Application_BeginRequest(Object sender, EventArgs e) in C:\www\Wiki\Screwturn3_0_2_509\WebApplication\Global.asax.cs:29 System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +68 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75 Discountasp says it's not a permission issue but obviously it is. I think /Wiki should work...but it's not. Here's my site viewed in FTP on discountasp.net's server:

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  • How much business logic belongs in RIA services layer?

    - by jkohlhepp
    I have been experimenting recently with Silverlight, RIA Services, and Entity Framework using .NET 4.0. I'm trying to figure out if that stack makes sense for use in any of my upcoming projects. It certainly seems like these technologies can be very productive for developing applications, but I'm struggling to decide how an application on top of this stack should be architected. The main issue I have is that in most of the demos I've seen most of the business logic ends up as DataAnnotations and custom validations in the RIA Services domain service class. This seems inappropriate to me. I view the domain service as basically a glorified web service that happens to make it easy to push information to the client. But most of what I've seen seems to orient the domain service as the main source of business logic in the application. So, my questions: What is the best location for business logic (rules, validations, behaviors, authorization) in an application using this stack? Are there any guidelines published at an architectural level for using this stack? My questions pertain to large, complex, and long-lived applications. Obviously for an application of only a few screens this is less of a concern. Edit: Another thing I meant to mention is that obviously you can make the domain service class stupid, but then you lose a lot of the automagic entity information (e.g. validations) being pushed to the client. And then if you lose that is there any point to using RIA services?

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  • Silverlight and WCF Ria Services

    - by Flex_Addicted
    Hi guys, I've created a new Silverlight 3 Business Application with VS 2008. The creation has completed correctly. When I try to open the xaml, it opens but in meanwhile this error is shown: Failed to load metadata assembly System.Windows.Controls.Data.Input.Design, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. Exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.. Stack Trace: at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)An exception of type ArgumentNullException was caught when calling IRegisterMetadata on type System.Windows.Controls.Data.Input.VisualStudio.Design.MetadataRegistration. Exception Message: Value cannot be null. Parameter name: type. Stack Trace: at Microsoft.Windows.Design.Metadata.AttributeTableBuilder.AddCallback(Type type, AttributeCallback callback) at System.Windows.Controls.Data.Input.VisualStudio.Design.MetadataRegistration.AddAttributes(AttributeTableBuilder builder) at System.Windows.Controls.Design.Common.MetadataRegistrationBase.BuildAttributeTable() at System.Windows.Controls.Data.Input.VisualStudio.Design.MetadataRegistration.Register() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)Failed to load metadata assembly System.Windows.Controls.Design, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. Exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.. Stack Trace: at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)Failed to load metadata assembly System.Windows.Controls.Navigation.Design, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. Exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.. Stack Trace: at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger) Why? Any solutions? Thank you in advance.

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  • Maximizing the number of true concurrent / parrallel http requests in Silverlight

    - by Clems
    Hi all. I'm using SL 4 beta and my app needs to do a lot of small http requests to the server. I believe that when exceeding the number of allowed concurrent requests, the subsequent requests are put in a queue. I am also aware that SL 4 has both a http browser stack and a http client stack, with both different limit in terms of the number of concurrent requests. Let's say call those limits MAX_BROWSER and MAX_CLIENT. Also I think I read somewhere that the number of concurrent requests is limited per domain, not overall. But I'm sure if this applies to both the http client stack. That means that you CAN have MAX_BROWSER requests to domain1.com AND MAX_BROWSER requests to domain2.com at the same time. And I even believe that sub domains are considered different so you can also have MAX_BROWSER requests to domain1.com AND MAX_BROWSER requests to sub.domain1.com at the same time. I have ownership of the services and domain names so I could easily setup sub domains for my services. Given those considerations I'm trying to optimize the number of concurrent http requests to my server. Here are few questions ? Is is possible to use both stack at the same time ? Is the subdomain/domain story true for both stacks ? None ? If so that would mean that I could potentially have a number of concurrent requests equal to : (MAX_BROWSER + MAX_CLIENT) * NUMBER_OF_DOMAINS which would be fairly good. Is this correct ? I'm kind of sharing my morning thoughts here, hoping somebody has experimented with those things. Thank you.

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  • How do interpreters functions written in the class C++ in the main

    - by T_Geek
    Hi I'm working on a project about Data structures. In the first , I wrote everything in main but it sounds like C . But as I learned, I tried to thinkk OOP and do as little as possible in my main() methods. I've implemented some opertation in my class like add,delet,find.it's too easy to implement its . class ARB { private: struct BT { int data; BT *l; BT *r; }; struct BT *p; public ARB(); ~ARB(); void del(int n); void add(int n); }; void ARB::del(int num) { //The code ,don't care about it }; main() { // BTR T; T.add(3); T.add(5); }; But I arrived to the big program How can I define a methode which have to use a binary tree and to get a stack STACK ARB::MyFunct(BT* p) { // The code don't care about it } How can I apply it in the main programme main() { // BT T; T.add(3); T.add(5); STACK S; BT* p S=T.MyFunct(p); // error C2664 cannot convert parametre 1 }; **mention :I implement STACK class

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  • Struts 2 how to display messages saved in a Interceptor which would redirec to another action?

    - by mui13
    in my interceptor, if user doesn't have enough right, there would be a warn message: public String intercept(ActionInvocation invocation) throws Exception { ActionContext actionContext = invocation.getInvocationContext(); Map<String, Object> sessionMap = actionContext.getSession(); User loginUser = (User) sessionMap.get("user"); Object action = invocation.getAction(); if (loginUser != null && loginUser.getRole().getId() != Constant.AUTHORITY_ADMIN) { ((ValidationAware) action).addFieldError("user.authority", ((DefaultAction) action).getText("user.action.authority.not.enough")); return DefaultAction.HOME_PAGE; } return invocation.invoke(); } then, it would redirect to "HOME_PAGE" action, if success, display information in the jsp. So how to display the warn message? i have used two interceptors configed in strust.xml, for admin right requirment: <interceptor-stack name="authorityStack"> <interceptor-ref name="authority" /> <interceptor-ref name="defaultStack" /> <interceptor-ref name="store"> <param name="operationMode">STORE</param> </interceptor-ref> </interceptor-stack> default is: <interceptor-stack name="default"> <interceptor-ref name="login" /> <interceptor-ref name="defaultStack" /> <interceptor-ref name="store"> <param name="operationMode">AUTOMATIC</param> </interceptor-ref> </interceptor-stack>

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  • What does the windbg command "kd" do?

    - by Oskar
    I ran kd by mistake and got some output that inteerested me, a reference to a line of code in my module that I can't see on the call stack of any thread. The lines weren't the beginnning of the method so I don't think the reference is to a function pointer, but possibly the result of an exception being stored in memory??? Of course, that happens to be what I'm looking for... Update: The stack trace of the exception is: 0:000> kb *** Stack trace for last set context - .thread/.cxr resets it ChildEBP RetAddr Args to Child 0174f168 734ea84f 2cb9e950 00000000 2cb9e950 kernel32!LoadTimeZoneInformation+0x2b 0174f1c4 734ead92 00000022 00000001 000685d0 msvbvm60! RUN_INSTMGR::ExecuteInitTerm+0x178 0174f1f8 734ea9ee 00000000 0000002f 2dbc2abc msvbvm60! RUN_INSTMGR::CreateObjInstanceWithParts+0x1e4 0174f278 7350414e 2cb9e96c 00000000 0174f2f0 msvbvm60! RUN_INSTMGR::CreateObjInstance+0x14d 0174f2e4 734fa071 00000000 2cb9e96c 0174f2fc msvbvm60!RcmConstructObjectInstance+0x75 0174f31c 00976ef1 2cb9e950 00591bc0 0174fddc msvbvm60!__vbaNew+0x21 and into our code (create a new Form derived class) the dds output: 0:000> dds esp-0x40 esp+0x100 0174f05c 00000000 0174f060 00000000 0174f064 00000000 0174f068 00000000 0174f06c 00000000 0174f070 00000000 0174f074 00000000 0174f078 00000000 0174f07c 00000000 0174f080 00000000 0174f084 00000000 0174f088 00000000 0174f08c 00000000 0174f090 00000000 0174f094 00000000 0174f098 00000000 0174f09c 007f4f9b ourDll!formDerivedClass::Form_Initialize+0x10b [C:\Buildbox\formDerivedClass.frm @ 1452] etc which seems to indicate that Initialize is being called even though it isn't on the stack trace of either this exception or any of the threads. As suggested, it might all be a mismatch between pdbs and dlls, but it seems a coincidence that we end up in the right classes and methods

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  • Are programming languages and methods inefficient? (assembler and C knowledge needed)

    - by b-gen-jack-o-neill
    Hi, for a long time, I am thinking and studying output of C language compiler in assembler form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually truly believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so. What exactly, do you ask? I´ll tell you right away, I use C as a example: 1: Stack local scope memory allocation: So, typical local memory allocation uses stack. Just copy esp to ebp and than allocate all the memory via ebp. OK, I would understand this if you explicitly need allocate RAM by default stack values, but if I do understand it correctly, modern OS use paging as a translation layer between application and physical RAM, when address you desire is further translated before reaching actual RAM byte. So why don´t just say 0x00000000 is int a,0x00000004 is int b and so? And access them just by mov 0x00000000,#10? Because you wont actually access memory blocks 0x00000000 and 0x00000004 but those your OS set the paging tables to. Actually, since memory allocation by ebp and esp use indirect addressing, "my" way would be even faster. 2: Variable allocation duplicity: When you run application, Loader load its code into RAM. When you create variable, or string, compiler generates code that pushes these values on the top o stack when created in main. So there is actual instruction for do so, and that actual number in memory. So, there are 2 entries of the same value in RAM. One in form of instruction, second in form of actual bytes in the RAM. But why? Why not to just when declaring variable count at which memory block it would be, than when used, just insert this memory location?

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  • Tracking down origin of I/O in multi-process server

    - by Craig Ringer
    I'm currently trying to track down some phantom I/O in a PostgreSQL build I'm testing. It's a multi-process server and it isn't simple to associate disk I/O back to a particular back-end and query. I thought Linux's perf tool would be ideal for this, but I'm struggling to capture block I/O performance counter metrics and associate them with user-space activity. It's easy to record block I/O requests and completions with, eg: sudo perf record -g -T -u postgres -e 'block:block_rq_*' and the user-space pid is recorded, but there's no kernel or user-space stack captured, or ability to snapshot bits of the user-space process's heap (say, query text) etc. So while you have the pid, you don't know what the process was doing at that point. Just perf script output like: postgres 7462 [002] 301125.113632: block:block_rq_issue: 8,0 W 0 () 208078848 + 1024 [postgres] If I add the -g flag to perf record it'll take snapshots of the kernel stack, but doesn't capture user-space state for perf events captured in the kernel. The user-space stack only goes up to the entry-point from userspace, like LWLockRelease, LWLockAcquire, memcpy (mmap'd IO), __GI___libc_write, etc. So. Any tips? Being able to capture a snapshot of the user-space stack in response to kernel events would be ideal.

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  • Adobe Air, packaged install fails with my trace routine... how come?

    - by artie scie
    I cobbled together some code from here and there for a trace I like... it generates an error to get a stack trace and picks out the traced routine name, I like that detail in the trace log. Problem: it fails in an installed AIR file. I wonder why? I don't expect it to do anything as is... just, I'd prefer it not cause the program to fail! tx artie enter code here static public function XTRACE( ... traceArgs ):void { try { throw new Error(); // make a stack } catch (e:Error) { var stack:String = e.getStackTrace(); var frames:Array = stack.split("\n"); var myFrame:String = String(frames[2]); myFrame = myFrame.replace("\t", ""); // "at " can be followed by some part of the package // you don't want to see. E.g., if your code is all in // com.foo.bar, you can put "at com.foo.bar." so as not // to crowd the display myFrame = myFrame.substr("at ".length); myFrame = myFrame.substring(0, myFrame.indexOf("[")); var now:Date = new Date(); trace(new Date().toLocaleTimeString() + ":" + myFrame + ": " + traceArgs.join(" ")); } }

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  • Are programming languages and methods ineffective? (assembler and C knowledge needed)

    - by b-gen-jack-o-neill
    Hi, for a long time, I am thinking and studying output of C language compiler in asemlber form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually trully believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so. What exactly, do you ask? I´ll tell you right away, I use C as a example: 1, Stack local scope memory allocation: So, typical local memory allocation uses stack. Just copy esp to ebp and than allocate all the memory via ebp. OK, I would understand this if you explicitly need allocate RAM by default stack values, but if I do understand it correctly, modern OS use paging as a translation layer between application and physical RAM, when adress you desire is further translated before reaching actuall RAM byte. So why don´t just say 0x00000000 is int a,0x00000004 is int b and so? And access them just by mov 0x00000000,#10? Becouse you wont actually access memory blocks 0x00000000 and 0x00000004 but those your OS set the paging tables to. Actually, since memory allocation by ebp and esp use indirect adressing, "my" way would be even faster. 2, Variable allocation duplicitly: When you run aaplication, Loader load its code into RAM. When you create variable, or string, compiler generates code that pushes these values on the top o stack when created in main. So there is actuall instruction for do so, and that actuall number in memory. So, there are 2 entries of the same value in RAM. One in fomr of instruction, second in form of actuall bytes in the RAM. But why? Why not to just when declaring variable count at which memory block it would be, than when used, just insert this memory location?

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  • Built-in GZip/Deflate Compression on IIS 7.x

    - by Rick Strahl
    IIS 7 improves internal compression functionality dramatically making it much easier than previous versions to take advantage of compression that’s built-in to the Web server. IIS 7 also supports dynamic compression which allows automatic compression of content created in your own applications (ASP.NET or otherwise!). The scheme is based on content-type sniffing and so it works with any kind of Web application framework. While static compression on IIS 7 is super easy to set up and turned on by default for most text content (text/*, which includes HTML and CSS, as well as for JavaScript, Atom, XAML, XML), setting up dynamic compression is a bit more involved, mostly because the various default compression settings are set in multiple places down the IIS –> ASP.NET hierarchy. Let’s take a look at each of the two approaches available: Static Compression Compresses static content from the hard disk. IIS can cache this content by compressing the file once and storing the compressed file on disk and serving the compressed alias whenever static content is requested and it hasn’t changed. The overhead for this is minimal and should be aggressively enabled. Dynamic Compression Works against application generated output from applications like your ASP.NET apps. Unlike static content, dynamic content must be compressed every time a page that requests it regenerates its content. As such dynamic compression has a much bigger impact than static caching. How Compression is configured Compression in IIS 7.x  is configured with two .config file elements in the <system.WebServer> space. The elements can be set anywhere in the IIS/ASP.NET configuration pipeline all the way from ApplicationHost.config down to the local web.config file. The following is from the the default setting in ApplicationHost.config (in the %windir%\System32\inetsrv\config forlder) on IIS 7.5 with a couple of small adjustments (added json output and enabled dynamic compression): <?xml version="1.0" encoding="UTF-8"?> <configuration> <system.webServer> <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files"> <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> <dynamicTypes> <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/json" enabled="true" /> <add mimeType="*/*" enabled="false" /> </dynamicTypes> <staticTypes> <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/atom+xml" enabled="true" /> <add mimeType="application/xaml+xml" enabled="true" /> <add mimeType="*/*" enabled="false" /> </staticTypes> </httpCompression> <urlCompression doStaticCompression="true" doDynamicCompression="true" /> </system.webServer> </configuration> You can find documentation on the httpCompression and urlCompression keys here respectively: http://msdn.microsoft.com/en-us/library/ms690689%28v=vs.90%29.aspx http://msdn.microsoft.com/en-us/library/aa347437%28v=vs.90%29.aspx The httpCompression Element – What and How to compress Basically httpCompression configures what types to compress and how to compress them. It specifies the DLL that handles gzip encoding and the types of documents that are to be compressed. Types are set up based on mime-types which looks at returned Content-Type headers in HTTP responses. For example, I added the application/json to mime type to my dynamic compression types above to allow that content to be compressed as well since I have quite a bit of AJAX content that gets sent to the client. The UrlCompression Element – Enables and Disables Compression The urlCompression element is a quick way to turn compression on and off. By default static compression is enabled server wide, and dynamic compression is disabled server wide. This might be a bit confusing because the httpCompression element also has a doDynamicCompression attribute which is set to true by default, but the urlCompression attribute by the same name actually overrides it. The urlCompression element only has three attributes: doStaticCompression, doDynamicCompression and dynamicCompressionBeforeCache. The doCompression attributes are the final determining factor whether compression is enabled, so it’s a good idea to be explcit! The default for doDynamicCompression='false”, but doStaticCompression="true"! Static Compression is enabled by Default, Dynamic Compression is not Because static compression is very efficient in IIS 7 it’s enabled by default server wide and there probably is no reason to ever change that setting. Dynamic compression however, since it’s more resource intensive, is turned off by default. If you want to enable dynamic compression there are a few quirks you have to deal with, namely that enabling it in ApplicationHost.config doesn’t work. Setting: <urlCompression doDynamicCompression="true" /> in applicationhost.config appears to have no effect and I had to move this element into my local web.config to make dynamic compression work. This is actually a smart choice because you’re not likely to want dynamic compression in every application on a server. Rather dynamic compression should be applied selectively where it makes sense. However, nowhere is it documented that the setting in applicationhost.config doesn’t work (or more likely is overridden somewhere and disabled lower in the configuration hierarchy). So: remember to set doDynamicCompression=”true” in web.config!!! How Static Compression works Static compression works against static content loaded from files on disk. Because this content is static and not bound to change frequently – such as .js, .css and static HTML content – it’s fairly easy for IIS to compress and then cache the compressed content. The way this works is that IIS compresses the files into a special folder on the server’s hard disk and then reads the content from this location if already compressed content is requested and the underlying file resource has not changed. The semantics of serving an already compressed file are very efficient – IIS still checks for file changes, but otherwise just serves the already compressed file from the compression folder. The compression folder is located at: %windir%\inetpub\temp\IIS Temporary Compressed Files\ApplicationPool\ If you look into the subfolders you’ll find compressed files: These files are pre-compressed and IIS serves them directly to the client until the underlying files are changed. As I mentioned before – static compression is on by default and there’s very little reason to turn that functionality off as it is efficient and just works out of the box. The one tweak you might want to do is to set the compression level to maximum. Since IIS only compresses content very infrequently it would make sense to apply maximum compression. You can do this with the staticCompressionLevel setting on the scheme element: <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> Other than that the default settings are probably just fine. Dynamic Compression – not so fast! By default dynamic compression is disabled and that’s actually quite sensible – you should use dynamic compression very carefully and think about what content you want to compress. In most applications it wouldn’t make sense to compress *all* generated content as it would generate a significant amount of overhead. Scott Fortsyth has a great post that details some of the performance numbers and how much impact dynamic compression has. Depending on how busy your server is you can play around with compression and see what impact it has on your server’s performance. There are also a few settings you can tweak to minimize the overhead of dynamic compression. Specifically the httpCompression key has a couple of CPU related keys that can help minimize the impact of Dynamic Compression on a busy server: dynamicCompressionDisableCpuUsage dynamicCompressionEnableCpuUsage By default these are set to 90 and 50 which means that when the CPU hits 90% compression will be disabled until CPU utilization drops back down to 50%. Again this is actually quite sensible as it utilizes CPU power from compression when available and falling off when the threshold has been hit. It’s a good way some of that extra CPU power on your big servers to use when utilization is low. Again these settings are something you likely have to play with. I would probably set the upper limit a little lower than 90% maybe around 70% to make this a feature that kicks in only if there’s lots of power to spare. I’m not really sure how accurate these CPU readings that IIS uses are as Cpu usage on Web Servers can spike drastically even during low loads. Don’t trust settings – do some load testing or monitor your server in a live environment to see what values make sense for your environment. Finally for dynamic compression I tend to add one Mime type for JSON data, since a lot of my applications send large chunks of JSON data over the wire. You can do that with the application/json content type: <add mimeType="application/json" enabled="true" /> What about Deflate Compression? The default compression is GZip. The documentation hints that you can use a different compression scheme and mentions Deflate compression. And sure enough you can change the compression settings to: <scheme name="deflate" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> to get deflate style compression. The deflate algorithm produces slightly more compact output so I tend to prefer it over GZip but more HTTP clients (other than browsers) support GZip than Deflate so be careful with this option if you build Web APIs. I also had some issues with the above value actually being applied right away. Changing the scheme in applicationhost.config didn’t show up on the site  right away. It required me to do a full IISReset to get that change to show up before I saw the change over to deflate compressed content. Content was slightly more compressed with deflate – not sure if it’s worth the slightly less common compression type, but the option at least is available. IIS 7 finally makes GZip Easy In summary IIS 7 makes GZip easy finally, even if the configuration settings are a bit obtuse and the documentation is seriously lacking. But once you know the basic settings I’ve described here and the fact that you can override all of this in your local web.config it’s pretty straight forward to configure GZip support and tweak it exactly to your needs. Static compression is a total no brainer as it adds very little overhead compared to direct static file serving and provides solid compression. Dynamic Compression is a little more tricky as it does add some overhead to servers, so it probably will require some tweaking to get the right balance of CPU load vs. compression ratios. Looking at large sites like Amazon, Yahoo, NewEgg etc. – they all use Related Content Code based ASP.NET GZip Caveats HttpWebRequest and GZip Responses © Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7   ASP.NET  

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  • C#/.NET Fundamentals: Choosing the Right Collection Class

    - by James Michael Hare
    The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table.  Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO   The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections.  If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher.   Tweet Technorati Tags: C#,.NET,Collecitons,Generic,Concurrent,Dictionary,List,Stack,Queue,SortedList,SortedDictionary,HashSet,SortedSet

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  • UAT Testing for SOA 10G Clusters

    - by [email protected]
    A lot of customers ask how to verify their SOA clusters and make them production ready. Here is a list that I recommend using for 10G SOA Clusters. v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-CA X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; mso-bidi-font-size:12.0pt; font-family:"Calibri","sans-serif"; mso-fareast-language:EN-US;} Test cases for each component - Oracle Application Server 10G General Application Server test cases This section is going to cover very General test cases to make sure that the Application Server cluster has been set up correctly and if you can start and stop all the components in the server via opmnct and AS Console. Test Case 1 Check if you can see AS instances in the console Implementation 1. Log on to the AS Console --> check to see if you can see all the nodes in your AS cluster. You should be able to see all the Oracle AS instances that are part of the cluster. This means that the OPMN clustering worked and the AS instances successfully joined the AS cluster. Result You should be able to see if all the instances in the AS cluster are listed in the EM console. If the instances are not listed here are the files to check to see if OPMN joined the cluster properly: $ORACLE_HOME\opmn\logs{*}opmn.log*$ORACLE_HOME\opmn\logs{*}opmn.dbg* If OPMN did not join the cluster properly, please check the opmn.xml file to make sure the discovery multicast address and port are correct (see this link  for opmn documentation). Restart the whole instance using opmnctl stopall followed by opmnctl startall. Log on to AS console to see if instance is listed as part of the cluster. Test Case 2 Check to see if you can start/stop each component Implementation Check each OC4J component on each AS instanceStart each and every component through the AS console to see if they will start and stop.Do that for each and every instance. Result Each component should start and stop through the AS console. You can also verify if the component started by checking opmnctl status by logging onto each box associated with the cluster Test Case 3 Add/modify a datasource entry through AS console on a remote AS instance (not on the instance where EM is physically running) Implementation Pick an OC4J instanceCreate a new data-source through the AS consoleModify an existing data-source or connection pool (optional) Result Open $ORACLE_HOME\j2ee\<oc4j_name>\config\data-sources.xml to see if the new (and or the modified) connection details and data-source exist. If they do then the AS console has successfully updated a remote file and MBeans are communicating correctly. Test Case 4 Start and stop AS instances using opmnctl @cluster command Implementation 1. Go to $ORACLE_HOME\opmn\bin and use the opmnctl @cluster to start and stop the AS instances Result Use opmnctl @cluster status to check for start and stop statuses.  HTTP server test cases This section will deal with use cases to test HTTP server failover scenarios. In these examples the HTTP server will be talking to the BPEL console (or any other web application that the client wants), so the URL will be _http://hostname:port\BPELConsole Test Case 1  Shut down one of the HTTP servers while accessing the BPEL console and see the requested routed to the second HTTP server in the cluster Implementation Access the BPELConsoleCheck $ORACLE_HOME\Apache\Apache\logs\access_log --> check for the timestamp and the URL that was accessed by the user. Timestamp and URL would look like this 1xx.2x.2xx.xxx [24/Mar/2009:16:04:38 -0500] "GET /BPELConsole=System HTTP/1.1" 200 15 After you have figured out which HTTP server this is running on, shut down this HTTP server by using opmnctl stopproc --> this is a graceful shutdown.Access the BPELConsole again (please note that you should have a LoadBalancer in front of the HTTP server and configured the Apache Virtual Host, see EDG for steps)Check $ORACLE_HOME\Apache\Apache\logs\access_log --> check for the timestamp and the URL that was accessed by the user. Timestamp and URL would look like above Result Even though you are shutting down the HTTP server the request is routed to the surviving HTTP server, which is then able to route the request to the BPEL Console and you are able to access the console. By checking the access log file you can confirm that the request is being picked up by the surviving node. Test Case 2 Repeat the same test as above but instead of calling opmnctl stopproc, pull the network cord of one of the HTTP servers, so that the LBR routes the request to the surviving HTTP node --> this is simulating a network failure. Test Case 3 In test case 1 we have simulated a graceful shutdown, in this case we will simulate an Apache crash Implementation Use opmnctl status -l to get the PID of the HTTP server that you would like forcefully bring downOn Linux use kill -9 <PID> to kill the HTTP serverAccess the BPEL console Result As you shut down the HTTP server, OPMN will restart the HTTP server. The restart may be so quick that the LBR may still route the request to the same server. One way to check if the HTTP server restared is to check the new PID and the timestamp in the access log for the BPEL console. BPEL test cases This section is going to cover scenarios dealing with BPEL clustering using jGroups, BPEL deployment and testing related to BPEL failover. Test Case 1 Verify that jGroups has initialized correctly. There is no real testing in this use case just a visual verification by looking at log files that jGroups has initialized correctly. Check the opmn log for the BPEL container for all nodes at $ORACLE_HOME/opmn/logs/<group name><container name><group name>~1.log. This logfile will contain jGroups related information during startup and steady-state operation. Soon after startup you should find log entries for UDP or TCP.Example jGroups Log Entries for UDPApr 3, 2008 6:30:37 PM org.collaxa.thirdparty.jgroups.protocols.UDP createSockets ·         INFO: sockets will use interface 144.25.142.172·          ·         Apr 3, 2008 6:30:37 PM org.collaxa.thirdparty.jgroups.protocols.UDP createSockets·          ·         INFO: socket information:·          ·         local_addr=144.25.142.172:1127, mcast_addr=228.8.15.75:45788, bind_addr=/144.25.142.172, ttl=32·         sock: bound to 144.25.142.172:1127, receive buffer size=64000, send buffer size=32000·         mcast_recv_sock: bound to 144.25.142.172:45788, send buffer size=32000, receive buffer size=64000·         mcast_send_sock: bound to 144.25.142.172:1128, send buffer size=32000, receive buffer size=64000·         Apr 3, 2008 6:30:37 PM org.collaxa.thirdparty.jgroups.protocols.TP$DiagnosticsHandler bindToInterfaces·          ·         -------------------------------------------------------·          ·         GMS: address is 144.25.142.172:1127·          ------------------------------------------------------- Example jGroups Log Entries for TCPApr 3, 2008 6:23:39 PM org.collaxa.thirdparty.jgroups.blocks.ConnectionTable start ·         INFO: server socket created on 144.25.142.172:7900·          ·         Apr 3, 2008 6:23:39 PM org.collaxa.thirdparty.jgroups.protocols.TP$DiagnosticsHandler bindToInterfaces·          ·         -------------------------------------------------------·         GMS: address is 144.25.142.172:7900------------------------------------------------------- In the log below the "socket created on" indicates that the TCP socket is established on the own node at that IP address and port the "created socket to" shows that the second node has connected to the first node, matching the logfile above with the IP address and port.Apr 3, 2008 6:25:40 PM org.collaxa.thirdparty.jgroups.blocks.ConnectionTable start ·         INFO: server socket created on 144.25.142.173:7901·          ·         Apr 3, 2008 6:25:40 PM org.collaxa.thirdparty.jgroups.protocols.TP$DiagnosticsHandler bindToInterfaces·          ·         ------------------------------------------------------·         GMS: address is 144.25.142.173:7901·         -------------------------------------------------------·         Apr 3, 2008 6:25:41 PM org.collaxa.thirdparty.jgroups.blocks.ConnectionTable getConnectionINFO: created socket to 144.25.142.172:7900  Result By reviewing the log files, you can confirm if BPEL clustering at the jGroups level is working and that the jGroup channel is communicating. Test Case 2  Test connectivity between BPEL Nodes Implementation Test connections between different cluster nodes using ping, telnet, and traceroute. The presence of firewalls and number of hops between cluster nodes can affect performance as they have a tendency to take down connections after some time or simply block them.Also reference Metalink Note 413783.1: "How to Test Whether Multicast is Enabled on the Network." Result Using the above tools you can confirm if Multicast is working  and whether BPEL nodes are commnunicating. Test Case3 Test deployment of BPEL suitcase to one BPEL node.  Implementation Deploy a HelloWorrld BPEL suitcase (or any other client specific BPEL suitcase) to only one BPEL instance using ant, or JDeveloper or via the BPEL consoleLog on to the second BPEL console to check if the BPEL suitcase has been deployed Result If jGroups has been configured and communicating correctly, BPEL clustering will allow you to deploy a suitcase to a single node, and jGroups will notify the second instance of the deployment. The second BPEL instance will go to the DB and pick up the new deployment after receiving notification. The result is that the new deployment will be "deployed" to each node, by only deploying to a single BPEL instance in the BPEL cluster. Test Case 4  Test to see if the BPEL server failsover and if all asynch processes are picked up by the secondary BPEL instance Implementation Deploy a 2 Asynch process: A ParentAsynch Process which calls a ChildAsynchProcess with a variable telling it how many times to loop or how many seconds to sleepA ChildAsynchProcess that loops or sleeps or has an onAlarmMake sure that the processes are deployed to both serversShut down one BPEL serverOn the active BPEL server call ParentAsynch a few times (use the load generation page)When you have enough ParentAsynch instances shut down this BPEL instance and start the other one. Please wait till this BPEL instance shuts down fully before starting up the second one.Log on to the BPEL console and see that the instance were picked up by the second BPEL node and completed Result The BPEL instance will failover to the secondary node and complete the flow ESB test cases This section covers the use cases involved with testing an ESB cluster. For this section please Normal 0 false false false EN-CA X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; mso-bidi-font-size:12.0pt; font-family:"Calibri","sans-serif"; mso-fareast-language:EN-US;} follow Metalink Note 470267.1 which covers the basic tests to verify your ESB cluster.

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  • Windows Azure Service Bus Splitter and Aggregator

    - by Alan Smith
    This article will cover basic implementations of the Splitter and Aggregator patterns using the Windows Azure Service Bus. The content will be included in the next release of the “Windows Azure Service Bus Developer Guide”, along with some other patterns I am working on. I’ve taken the pattern descriptions from the book “Enterprise Integration Patterns” by Gregor Hohpe. I bought a copy of the book in 2004, and recently dusted it off when I started to look at implementing the patterns on the Windows Azure Service Bus. Gregor has also presented an session in 2011 “Enterprise Integration Patterns: Past, Present and Future” which is well worth a look. I’ll be covering more patterns in the coming weeks, I’m currently working on Wire-Tap and Scatter-Gather. There will no doubt be a section on implementing these patterns in my “SOA, Connectivity and Integration using the Windows Azure Service Bus” course. There are a number of scenarios where a message needs to be divided into a number of sub messages, and also where a number of sub messages need to be combined to form one message. The splitter and aggregator patterns provide a definition of how this can be achieved. This section will focus on the implementation of basic splitter and aggregator patens using the Windows Azure Service Bus direct programming model. In BizTalk Server receive pipelines are typically used to implement the splitter patterns, with sequential convoy orchestrations often used to aggregate messages. In the current release of the Service Bus, there is no functionality in the direct programming model that implements these patterns, so it is up to the developer to implement them in the applications that send and receive messages. Splitter A message splitter takes a message and spits the message into a number of sub messages. As there are different scenarios for how a message can be split into sub messages, message splitters are implemented using different algorithms. The Enterprise Integration Patterns book describes the splatter pattern as follows: How can we process a message if it contains multiple elements, each of which may have to be processed in a different way? Use a Splitter to break out the composite message into a series of individual messages, each containing data related to one item. The Enterprise Integration Patterns website provides a description of the Splitter pattern here. In some scenarios a batch message could be split into the sub messages that are contained in the batch. The splitting of a message could be based on the message type of sub-message, or the trading partner that the sub message is to be sent to. Aggregator An aggregator takes a stream or related messages and combines them together to form one message. The Enterprise Integration Patterns book describes the aggregator pattern as follows: How do we combine the results of individual, but related messages so that they can be processed as a whole? Use a stateful filter, an Aggregator, to collect and store individual messages until a complete set of related messages has been received. Then, the Aggregator publishes a single message distilled from the individual messages. The Enterprise Integration Patterns website provides a description of the Aggregator pattern here. A common example of the need for an aggregator is in scenarios where a stream of messages needs to be combined into a daily batch to be sent to a legacy line-of-business application. The BizTalk Server EDI functionality provides support for batching messages in this way using a sequential convoy orchestration. Scenario The scenario for this implementation of the splitter and aggregator patterns is the sending and receiving of large messages using a Service Bus queue. In the current release, the Windows Azure Service Bus currently supports a maximum message size of 256 KB, with a maximum header size of 64 KB. This leaves a safe maximum body size of 192 KB. The BrokeredMessage class will support messages larger than 256 KB; in fact the Size property is of type long, implying that very large messages may be supported at some point in the future. The 256 KB size restriction is set in the service bus components that are deployed in the Windows Azure data centers. One of the ways of working around this size restriction is to split large messages into a sequence of smaller sub messages in the sending application, send them via a queue, and then reassemble them in the receiving application. This scenario will be used to demonstrate the pattern implementations. Implementation The splitter and aggregator will be used to provide functionality to send and receive large messages over the Windows Azure Service Bus. In order to make the implementations generic and reusable they will be implemented as a class library. The splitter will be implemented in the LargeMessageSender class and the aggregator in the LargeMessageReceiver class. A class diagram showing the two classes is shown below. Implementing the Splitter The splitter will take a large brokered message, and split the messages into a sequence of smaller sub-messages that can be transmitted over the service bus messaging entities. The LargeMessageSender class provides a Send method that takes a large brokered message as a parameter. The implementation of the class is shown below; console output has been added to provide details of the splitting operation. public class LargeMessageSender {     private static int SubMessageBodySize = 192 * 1024;     private QueueClient m_QueueClient;       public LargeMessageSender(QueueClient queueClient)     {         m_QueueClient = queueClient;     }       public void Send(BrokeredMessage message)     {         // Calculate the number of sub messages required.         long messageBodySize = message.Size;         int nrSubMessages = (int)(messageBodySize / SubMessageBodySize);         if (messageBodySize % SubMessageBodySize != 0)         {             nrSubMessages++;         }           // Create a unique session Id.         string sessionId = Guid.NewGuid().ToString();         Console.WriteLine("Message session Id: " + sessionId);         Console.Write("Sending {0} sub-messages", nrSubMessages);           Stream bodyStream = message.GetBody<Stream>();         for (int streamOffest = 0; streamOffest < messageBodySize;             streamOffest += SubMessageBodySize)         {                                     // Get the stream chunk from the large message             long arraySize = (messageBodySize - streamOffest) > SubMessageBodySize                 ? SubMessageBodySize : messageBodySize - streamOffest;             byte[] subMessageBytes = new byte[arraySize];             int result = bodyStream.Read(subMessageBytes, 0, (int)arraySize);             MemoryStream subMessageStream = new MemoryStream(subMessageBytes);               // Create a new message             BrokeredMessage subMessage = new BrokeredMessage(subMessageStream, true);             subMessage.SessionId = sessionId;               // Send the message             m_QueueClient.Send(subMessage);             Console.Write(".");         }         Console.WriteLine("Done!");     }} The LargeMessageSender class is initialized with a QueueClient that is created by the sending application. When the large message is sent, the number of sub messages is calculated based on the size of the body of the large message. A unique session Id is created to allow the sub messages to be sent as a message session, this session Id will be used for correlation in the aggregator. A for loop in then used to create the sequence of sub messages by creating chunks of data from the stream of the large message. The sub messages are then sent to the queue using the QueueClient. As sessions are used to correlate the messages, the queue used for message exchange must be created with the RequiresSession property set to true. Implementing the Aggregator The aggregator will receive the sub messages in the message session that was created by the splitter, and combine them to form a single, large message. The aggregator is implemented in the LargeMessageReceiver class, with a Receive method that returns a BrokeredMessage. The implementation of the class is shown below; console output has been added to provide details of the splitting operation.   public class LargeMessageReceiver {     private QueueClient m_QueueClient;       public LargeMessageReceiver(QueueClient queueClient)     {         m_QueueClient = queueClient;     }       public BrokeredMessage Receive()     {         // Create a memory stream to store the large message body.         MemoryStream largeMessageStream = new MemoryStream();           // Accept a message session from the queue.         MessageSession session = m_QueueClient.AcceptMessageSession();         Console.WriteLine("Message session Id: " + session.SessionId);         Console.Write("Receiving sub messages");           while (true)         {             // Receive a sub message             BrokeredMessage subMessage = session.Receive(TimeSpan.FromSeconds(5));               if (subMessage != null)             {                 // Copy the sub message body to the large message stream.                 Stream subMessageStream = subMessage.GetBody<Stream>();                 subMessageStream.CopyTo(largeMessageStream);                   // Mark the message as complete.                 subMessage.Complete();                 Console.Write(".");             }             else             {                 // The last message in the sequence is our completeness criteria.                 Console.WriteLine("Done!");                 break;             }         }                     // Create an aggregated message from the large message stream.         BrokeredMessage largeMessage = new BrokeredMessage(largeMessageStream, true);         return largeMessage;     } }   The LargeMessageReceiver initialized using a QueueClient that is created by the receiving application. The receive method creates a memory stream that will be used to aggregate the large message body. The AcceptMessageSession method on the QueueClient is then called, which will wait for the first message in a message session to become available on the queue. As the AcceptMessageSession can throw a timeout exception if no message is available on the queue after 60 seconds, a real-world implementation should handle this accordingly. Once the message session as accepted, the sub messages in the session are received, and their message body streams copied to the memory stream. Once all the messages have been received, the memory stream is used to create a large message, that is then returned to the receiving application. Testing the Implementation The splitter and aggregator are tested by creating a message sender and message receiver application. The payload for the large message will be one of the webcast video files from http://www.cloudcasts.net/, the file size is 9,697 KB, well over the 256 KB threshold imposed by the Service Bus. As the splitter and aggregator are implemented in a separate class library, the code used in the sender and receiver console is fairly basic. The implementation of the main method of the sending application is shown below.   static void Main(string[] args) {     // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Use the MessagingFactory to create a queue client     QueueClient queueClient = factory.CreateQueueClient(AccountDetails.QueueName);       // Open the input file.     FileStream fileStream = new FileStream(AccountDetails.TestFile, FileMode.Open);       // Create a BrokeredMessage for the file.     BrokeredMessage largeMessage = new BrokeredMessage(fileStream, true);       Console.WriteLine("Sending: " + AccountDetails.TestFile);     Console.WriteLine("Message body size: " + largeMessage.Size);     Console.WriteLine();         // Send the message with a LargeMessageSender     LargeMessageSender sender = new LargeMessageSender(queueClient);     sender.Send(largeMessage);       // Close the messaging facory.     factory.Close();  } The implementation of the main method of the receiving application is shown below. static void Main(string[] args) {       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Use the MessagingFactory to create a queue client     QueueClient queueClient = factory.CreateQueueClient(AccountDetails.QueueName);       // Create a LargeMessageReceiver and receive the message.     LargeMessageReceiver receiver = new LargeMessageReceiver(queueClient);     BrokeredMessage largeMessage = receiver.Receive();       Console.WriteLine("Received message");     Console.WriteLine("Message body size: " + largeMessage.Size);       string testFile = AccountDetails.TestFile.Replace(@"\In\", @"\Out\");     Console.WriteLine("Saving file: " + testFile);       // Save the message body as a file.     Stream largeMessageStream = largeMessage.GetBody<Stream>();     largeMessageStream.Seek(0, SeekOrigin.Begin);     FileStream fileOut = new FileStream(testFile, FileMode.Create);     largeMessageStream.CopyTo(fileOut);     fileOut.Close();       Console.WriteLine("Done!"); } In order to test the application, the sending application is executed, which will use the LargeMessageSender class to split the message and place it on the queue. The output of the sender console is shown below. The console shows that the body size of the large message was 9,929,365 bytes, and the message was sent as a sequence of 51 sub messages. When the receiving application is executed the results are shown below. The console application shows that the aggregator has received the 51 messages from the message sequence that was creating in the sending application. The messages have been aggregated to form a massage with a body of 9,929,365 bytes, which is the same as the original large message. The message body is then saved as a file. Improvements to the Implementation The splitter and aggregator patterns in this implementation were created in order to show the usage of the patterns in a demo, which they do quite well. When implementing these patterns in a real-world scenario there are a number of improvements that could be made to the design. Copying Message Header Properties When sending a large message using these classes, it would be great if the message header properties in the message that was received were copied from the message that was sent. The sending application may well add information to the message context that will be required in the receiving application. When the sub messages are created in the splitter, the header properties in the first message could be set to the values in the original large message. The aggregator could then used the values from this first sub message to set the properties in the message header of the large message during the aggregation process. Using Asynchronous Methods The current implementation uses the synchronous send and receive methods of the QueueClient class. It would be much more performant to use the asynchronous methods, however doing so may well affect the sequence in which the sub messages are enqueued, which would require the implementation of a resequencer in the aggregator to restore the correct message sequence. Handling Exceptions In order to keep the code readable no exception handling was added to the implementations. In a real-world scenario exceptions should be handled accordingly.

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  • How can I get the following compiled on UVA?

    - by Michael Tsang
    Note the comment below. It cannot compiled on UVA because of a bug in GCC. #include <cstdio> #include <cstring> #include <cctype> #include <map> #include <stdexcept> class Board { public: bool read(FILE *); enum Colour {none, white, black}; Colour check() const; private: struct Index { size_t x; size_t y; Index &operator+=(const Index &) throw(std::range_error); Index operator+(const Index &) const throw(std::range_error); }; const static std::size_t size = 8; char data[size][size]; // Cannot be compiled on GCC 4.1.2 due to GCC bug 29993 // http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29993 typedef bool CheckFunction(Colour, const Index &) const; CheckFunction pawn, knight, bishop, king, rook; bool queen(const Colour c, const Index &location) const { return rook(c, location) || bishop(c, location); } static char get_king(Colour c) { return c == white ? 'k' : 'K'; } template<std::size_t n> bool check_consecutive(Colour c, const Index &location, const Index (&offsets)[n]) const { for(const Index *p = offsets; p != (&offsets)[1]; ++p) { try { Index target = location + *p; for(; data[target.x][target.y] == '.'; target += *p) { } if(data[target.x][target.y] == get_king(c)) return true; } catch(std::range_error &) { } } return false; } template<std::size_t n> bool check_distinct(Colour c, const Index &location, const Index (&offsets)[n]) const { for(const Index *p = offsets; p != (&offsets)[1]; ++p) { try { Index target = location + *p; if(data[target.x][target.y] == get_king(c)) return true; } catch(std::range_error &) { } } return false; } }; int main() { Board board; for(int d = 1; board.read(stdin); ++d) { Board::Colour c = board.check(); const char *sp; switch(c) { case Board::black: sp = "white"; break; case Board::white: sp = "black"; break; case Board::none: sp = "no"; break; } std::printf("Game #%d: %s king is in check.\n", d, sp); std::getchar(); // discard empty line } } bool Board::read(FILE *f) { static const char empty[] = "........" "........" "........" "........" "........" "........" "........" "........"; // 64 dots for(char (*p)[size] = data; p != (&data)[1]; ++p) { std::fread(*p, size, 1, f); std::fgetc(f); // discard new-line } return std::memcmp(empty, data, sizeof data); } Board::Colour Board::check() const { std::map<char, CheckFunction Board::*> fp; fp['P'] = &Board::pawn; fp['N'] = &Board::knight; fp['B'] = &Board::bishop; fp['Q'] = &Board::queen; fp['K'] = &Board::king; fp['R'] = &Board::rook; for(std::size_t i = 0; i != size; ++i) { for(std::size_t j = 0; j != size; ++j) { CheckFunction Board::* p = fp[std::toupper(data[i][j])]; if(p) { Colour ret; if(std::isupper(data[i][j])) ret = white; else ret = black; if((this->*p)(ret, (Index){i, j}/* C99 extension */)) return ret; } } } return none; } bool Board::pawn(const Colour c, const Index &location) const { const std::ptrdiff_t sh = c == white ? -1 : 1; const Index offsets[] = { {sh, 1}, {sh, -1} }; return check_distinct(c, location, offsets); } bool Board::knight(const Colour c, const Index &location) const { static const Index offsets[] = { {1, 2}, {2, 1}, {2, -1}, {1, -2}, {-1, -2}, {-2, -1}, {-2, 1}, {-1, 2} }; return check_distinct(c, location, offsets); } bool Board::bishop(const Colour c, const Index &location) const { static const Index offsets[] = { {1, 1}, {1, -1}, {-1, -1}, {-1, 1} }; return check_consecutive(c, location, offsets); } bool Board::rook(const Colour c, const Index &location) const { static const Index offsets[] = { {1, 0}, {0, -1}, {0, 1}, {-1, 0} }; return check_consecutive(c, location, offsets); } bool Board::king(const Colour c, const Index &location) const { static const Index offsets[] = { {-1, -1}, {-1, 0}, {-1, 1}, {0, 1}, {1, 1}, {1, 0}, {1, -1}, {0, -1} }; return check_distinct(c, location, offsets); } Board::Index &Board::Index::operator+=(const Index &rhs) throw(std::range_error) { if(x + rhs.x >= size || y + rhs.y >= size) throw std::range_error("result is larger than size"); x += rhs.x; y += rhs.y; return *this; } Board::Index Board::Index::operator+(const Index &rhs) const throw(std::range_error) { Index ret = *this; return ret += rhs; }

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  • Strange (Undefined?) Behavior of Free in C

    - by Chris Cirefice
    This is really strange... and I can't debug it (tried for about two hours, debugger starts going haywire after a while...). Anyway, I'm trying to do something really simple: Free an array of strings. The array is in the form: char **myStrings. The array elements are initialized as: myString[index] = malloc(strlen(word)); myString[index] = word; and I'm calling a function like this: free_memory(myStrings, size); where size is the length of the array (I know this is not the problem, I tested it extensively and everything except this function is working). free_memory looks like this: void free_memory(char **list, int size) { for (int i = 0; i < size; i ++) { free(list[i]); } free(list); } Now here comes the weird part. if (size> strlen(list[i])) then the program crashes. For example, imagine that I have a list of strings that looks something like this: myStrings[0] = "Some"; myStrings[1] = "random"; myStrings[2] = "strings"; And thus the length of this array is 3. If I pass this to my free_memory function, strlen(myStrings[0]) > 3 (4 3), and the program crashes. However, if I change myStrings[0] to be "So" instead, then strlen(myStrings[0]) < 3 (2 < 3) and the program does not crash. So it seems to me that free(list[i]) is actually going through the char[] that is at that location and trying to free each character, which I imagine is undefined behavior. The only reason I say this is because I can play around with the size of the first element of myStrings and make the program crash whenever I feel like it, so I'm assuming that this is the problem area. Note: I did try to debug this by stepping through the function that calls free_memory, noting any weird values and such, but the moment I step into the free_memory function, the debugger crashes, so I'm not really sure what is going on. Nothing is out of the ordinary until I enter the function, then the world explodes. Another note: I also posted the shortened version of the source for this program (not too long; Pastebin) here. I am compiling on MinGW with the c99 flag on. PS - I just thought of this. I am indeed passing numUniqueWords to the free function, and I know that this does not actually free the entire piece of memory that I allocated. I've called it both ways, that's not the issue. And I left it how I did because that is the way that I will be calling it after I get it to work in the first place, I need to revise some of my logic in that function. Source, as per request (on-site): #include <stdio.h> #include <string.h> #include <ctype.h> #include <stdlib.h> #include "words.h" int getNumUniqueWords(char text[], int size); int main(int argc, char* argv[]) { setvbuf(stdout, NULL, 4, _IONBF); // For Eclipse... stupid bug. --> does NOT affect the program, just the output to console! int nbr_words; char text[] = "Some - \"text, a stdin\". We'll have! also repeat? We'll also have a repeat!"; int length = sizeof(text); nbr_words = getNumUniqueWords(text, length); return 0; } void free_memory(char **list, int size) { for (int i = 0; i < size; i ++) { // You can see that printing the values is fine, as long as free is not called. // When free is called, the program will crash if (size > strlen(list[i])) //printf("Wanna free value %d w/len of %d: %s\n", i, strlen(list[i]), list[i]); free(list[i]); } free(list); } int getNumUniqueWords(char text[], int length) { int numTotalWords = 0; char *word; printf("Length: %d characters\n", length); char totalWords[length]; strcpy(totalWords, text); word = strtok(totalWords, " ,.-!?()\"0123456789"); while (word != NULL) { numTotalWords ++; printf("%s\n", word); word = strtok(NULL, " ,.-!?()\"0123456789"); } printf("Looks like we counted %d total words\n\n", numTotalWords); char *uniqueWords[numTotalWords]; char *tempWord; int wordAlreadyExists = 0; int numUniqueWords = 0; char totalWordsCopy[length]; strcpy(totalWordsCopy, text); for (int i = 0; i < numTotalWords; i++) { uniqueWords[i] = NULL; } // Tokenize until all the text is consumed. word = strtok(totalWordsCopy, " ,.-!?()\"0123456789"); while (word != NULL) { // Look through the word list for the current token. for (int j = 0; j < numTotalWords; j ++) { // Just for clarity, no real meaning. tempWord = uniqueWords[j]; // The word list is either empty or the current token is not in the list. if (tempWord == NULL) { break; } //printf("Comparing (%s) with (%s)\n", tempWord, word); // If the current token is the same as the current element in the word list, mark and break if (strcmp(tempWord, word) == 0) { printf("\nDuplicate: (%s)\n\n", word); wordAlreadyExists = 1; break; } } // Word does not exist, add it to the array. if (!wordAlreadyExists) { uniqueWords[numUniqueWords] = malloc(strlen(word)); uniqueWords[numUniqueWords] = word; numUniqueWords ++; printf("Unique: %s\n", word); } // Reset flags and continue. wordAlreadyExists = 0; word = strtok(NULL, " ,.-!?()\"0123456789"); } // Print out the array just for funsies - make sure it's working properly. for (int x = 0; x <numUniqueWords; x++) { printf("Unique list %d: %s\n", x, uniqueWords[x]); } printf("\nNumber of unique words: %d\n\n", numUniqueWords); // Right below is where things start to suck. free_memory(uniqueWords, numUniqueWords); return numUniqueWords; }

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  • Submiting a Form without Refreshing the page with jQuery and Ajax Not updating MySQL database.

    - by HEEEEEEELP
    I'm a newbie to JQuery and have a problem, when I click submit button on the form everything says registration was successful but my MYSQL database was not updated everything worked fine until I tried to add the JQuery to the picture. Can someone help me fix this problem so my database is updated? Thanks Here is the JQuery code. $(function() { $(".save-button").click(function() { var address = $("#address").val(); var address_two = $("#address_two").val(); var city_town = $("#city_town").val(); var state_province = $("#state_province").val(); var zipcode = $("#zipcode").val(); var country = $("#country").val(); var email = $("#email").val(); var dataString = 'address='+ address + '&address_two=' + address_two + '&city_town=' + city_town + '&state_province=' + state_province + '&zipcode=' + zipcode + '&country=' + country + '$email=' + email; if(address=='' || address_two=='' || city_town=='' || state_province=='' || zipcode=='' || country=='' || email=='') { $('.success').fadeOut(200).hide(); $('.error').fadeOut(200).show(); } else { $.ajax({ type: "POST", url: "http://localhost/New%20Project/home/index.php", data: dataString, success: function(){ $('.success').fadeIn(200).show(); $('.error').fadeOut(200).hide(); } }); } return false; }); }); Here is the PHP code. if (isset($_POST['contact_info_submitted'])) { // Handle the form. // Query member data from the database and ready it for display $mysqli = mysqli_connect("localhost", "root", "", "sitename"); $dbc = mysqli_query($mysqli,"SELECT users.*, contact_info.* FROM users INNER JOIN contact_info ON contact_info.user_id = users.user_id WHERE users.user_id=3"); $user_id = mysqli_real_escape_string($mysqli, htmlentities('3')); $address = mysqli_real_escape_string($mysqli, htmlentities($_POST['address'])); $address_two = mysqli_real_escape_string($mysqli, htmlentities($_POST['address_two'])); $city_town = mysqli_real_escape_string($mysqli, htmlentities($_POST['city_town'])); $state_province = mysqli_real_escape_string($mysqli, htmlentities($_POST['state_province'])); $zipcode = mysqli_real_escape_string($mysqli, htmlentities($_POST['zipcode'])); $country = mysqli_real_escape_string($mysqli, htmlentities($_POST['country'])); $email = mysqli_real_escape_string($mysqli, strip_tags($_POST['email'])); //If the table is not found add it to the database if (mysqli_num_rows($dbc) == 0) { $mysqli = mysqli_connect("localhost", "root", "", "sitename"); $dbc = mysqli_query($mysqli,"INSERT INTO contact_info (user_id, address, address_two, city_town, state_province, zipcode, country, email) VALUES ('$user_id', '$address', '$address_two', '$city_town', '$state_province', '$zipcode', '$country', '$email')"); } //If the table is in the database update each field when needed if ($dbc == TRUE) { $dbc = mysqli_query($mysqli,"UPDATE contact_info SET address = '$address', address_two = '$address_two', city_town = '$city_town', state_province = '$state_province', zipcode = '$zipcode', country = '$country', email = '$email' WHERE user_id = '$user_id'"); } if (!$dbc) { // There was an error...do something about it here... print mysqli_error($mysqli); return; } } Here is the XHTML code. <form method="post" action="index.php"> <fieldset> <ul> <li><label for="address">Address 1: </label><input type="text" name="address" id="address" size="25" class="input-size" value="<?php if (isset($_POST['address'])) { echo $_POST['address']; } else if(!empty($address)) { echo $address; } ?>" /></li> <li><label for="address_two">Address 2: </label><input type="text" name="address_two" id="address_two" size="25" class="input-size" value="<?php if (isset($_POST['address_two'])) { echo $_POST['address_two']; } else if(!empty($address_two)) { echo $address_two; } ?>" /></li> <li><label for="city_town">City/Town: </label><input type="text" name="city_town" id="city_town" size="25" class="input-size" value="<?php if (isset($_POST['city_town'])) { echo $_POST['city_town']; } else if(!empty($city_town)) { echo $city_town; } ?>" /></li> <li><label for="state_province">State/Province: </label> <?php echo '<select name="state_province" id="state_province">' . "\n"; foreach($state_options as $option) { if ($option == $state_province) { echo '<option value="' . $option . '" selected="selected">' . $option . '</option>' . "\n"; } else { echo '<option value="'. $option . '">' . $option . '</option>'."\n"; } } echo '</select>'; ?> </li> <li><label for="zipcode">Zip/Post Code: </label><input type="text" name="zipcode" id="zipcode" size="5" class="input-size" value="<?php if (isset($_POST['zipcode'])) { echo $_POST['zipcode']; } else if(!empty($zipcode)) { echo $zipcode; } ?>" /></li> <li><label for="country">Country: </label> <?php echo '<select name="country" id="country">' . "\n"; foreach($countries as $option) { if ($option == $country) { echo '<option value="' . $option . '" selected="selected">' . $option . '</option>' . "\n"; } else if($option == "-------------") { echo '<option value="' . $option . '" disabled="disabled">' . $option . '</option>'; } else { echo '<option value="'. $option . '">' . $option . '</option>'."\n"; } } echo '</select>'; ?> </li> <li><label for="email">Email Address: </label><input type="text" name="email" id="email" size="25" class="input-size" value="<?php if (isset($_POST['email'])) { echo $_POST['email']; } else if(!empty($email)) { echo $email; } ?>" /><br /><span>We don't spam or share your email with third parties. We respect your privacy.</span></li> <li><input type="submit" name="submit" value="Save Changes" class="save-button" /> <input type="hidden" name="contact_info_submitted" value="true" /> <input type="submit" name="submit" value="Preview Changes" class="preview-changes-button" /></li> </ul> </fieldset> </form>

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  • How Should I Generate Trade Statistics For CouchDB/Rails3 Application?

    - by James
    My Problem: I am trying to developing a web application for currency traders. The application allows traders to enter or upload information about their trades and I want to calculate a wide variety of statistics based on what the user entered. Now, normally I would use a relational database for this, but I have two requirements that don't fit well with a relational database so I am attempting to use couchdb. Those two problems are: 1) Primarily, I have a companion desktop application that users will be able to work with and replicate to the site using couchdb's awesome replication feature and 2) I would like to allow users to be able to define their own custom things to track about trades and generate results based off of what they enter. The schema less nature of couch seems perfect here, but it may end up being harder than it sounds. (I already know couch requires you to define views in advance and such so I was just planning on sticking all the custom attributes in an array and then emitting the array in the view and further processing from there.) What I Am Doing: Right now I am just emitting each trade in couch keyed by each user's system and querying with the key of the system to get an array of trades per system. Simple. I am not using a reduce function currently to calculate any stats because I couldn't figure out how to get everything I need without getting a reduce overflow error. Here is an example of rows that are getting emitted from couch: {"total_rows":134,"offset":0,"rows":[ {"id":"5b1dcd47221e160d8721feee4ccc64be", "key":["80e40ba2fa43589d57ec3f1d19db41e6","2010/05/14 04:32:37 +0000"], null, "doc":{ "_id":"5b1dcd47221e160d8721feee4ccc64be", "_rev":"1-bc9fe763e2637694df47d6f5efb58e5b", "couchrest-type":"Trade", "system":"80e40ba2fa43589d57ec3f1d19db41e6", "pair":"EUR/USD", "direction":"Buy", "entry":12600, "exit":12700, "stop_loss":12500, "profit_target":12700, "status":"Closed", "slug":"101332132375", "custom_tracking": [{"name":"signal", "value":"Pin Bar"}] "updated_at":"2010/05/14 04:32:37 +0000", "created_at":"2010/05/14 04:32:37 +0000", "result":100}} ]} In my rails 3 controller I am basically just populating an array of trades such as the one above and then extracting out the relevant data into smaller arrays that I can compute my statistics on. Here is my show action for the page that I want to display the stats and all the trades: def show @trades = Trade.by_system(:startkey => [@system.id], :endkey => [@system.id, Time.now ]) @trades.each do |trade| if trade.result > 0 @winning_trades << trade.result elsif trade.result < 0 @losing_trades << trade.result else @breakeven_trades << trade.result end if trade.direction == "Buy" @long_trades << trade.result else @short_trades << trade.result end if trade["custom_tracking"] != nil @custom_tracking << {"result" => trade.result, "variables" => trade["custom_tracking"]} end end end I am omitting some other stuff that is going on, but that is the gist of what I am doing. Then I am calculating stuff in the view layer to produce some results: <% winning_long_trades = @long_trades.reject {|trade| trade <= 0 } %> <% winning_short_trades = @short_trades.reject {|trade| trade <= 0 } %> <ul> <li>Total Trades: <%= @trades.count %></li> <li>Winners: <%= @winning_trades.size %></li> <li>Biggest Winner (Pips): <%= @winning_trades.max %></li> <li>Average Win(Pips): <%= @winning_trades.sum/@winning_trades.size %></li> <li>Losers: <%= @losing_trades.size %></li> <li>Biggest Loser (Pips): <%= @losing_trades.min %></li> <li>Average Loss(Pips): <%= @losing_trades.sum/@losing_trades.size %></li> <li>Breakeven Trades: <%= @breakeven_trades.size %></li> <li>Long Trades: <%= @long_trades.size %></li> <li>Winning Long Trades: <%= winning_long_trades.size %></li> <li>Short Trades: <%= @short_trades.size %></li> <li>Winning Short Trades: <%= winning_short_trades.size %></li> <li>Total Pips: <%= @winning_trades.sum + @losing_trades.sum %></li> <li>Win Rate (%): <%= @winning_trades.size/@trades.count.to_f * 100 %></li> </ul> This produces the following results, which aside from a few things is exactly what I want: Total Trades: 134 Winners: 70 Biggest Winner (Pips): 1488 Average Win(Pips): 440 Losers: 58 Biggest Loser (Pips): -516 Average Loss(Pips): -225 Breakeven Trades: 6 Long Trades: 125 Winning Long Trades: 67 Short Trades: 9 Winning Short Trades: 3 Total Pips: 17819 Win Rate (%): 52.23880597014925 What I Am Wondering- Finally The Actual Questions: I am starting to get really skeptical of how well this method will work when a user has 5,000 trades instead of just 134 like in this example. I anticipate most users will only have somewhere under 200 per year, but some users may have a couple thousand trades per year. Probably no more than 5,000 per year. It seems to work ok now, but the page load times are already getting a tad high for my tastes. (About 800ms to generate the page according to rails logs with about a 250ms of that spent in the view layer.) I will end up caching this page I am sure, but I still need the regenerate the page each time a trade is updated and I can't afford to have this be too slow. Sooo..... Is doing something similar here possible with a straight couchdb reduce function? I am assuming handing this off to couch would possibly help with larger data sets. I couldn't figure out how, but I suppose that doesn't mean it isn't possible. If possible, any hints will be helpful. Could I use a list function if a reduce was not available due to reduce constraints? Are couchdb list functions suitable for this type of calculations? Anyone have any idea of whether or not list functions perform well? Any hints what one would look like for the type of calculations I am trying to achieve? I thought about other options such as running the calculations at the time each trade was saved or nightly if I had to and saving the results to a statistics doc that I could then query so that all the processing was done ahead of time. I would like this to be the last resort because then I can't really filter out trades by time periods dynamically like I would really like to. (I want to have a slider that a user can slide to only show trades from that time period using the startkey and endkey in couchdb if I can.) If I should continue running the calculations inside the rails app at the time of the page view, what can I do to improve my current implementation. I am new to rails, couch and programming in general. I am sure that I could be doing something better here. Do I need to create an array for each stat or is there a better way to do that. I guess I just would really like some advice on how to tackle this problem. I want to keep the page generation time minimal since I anticipate these being some of the highest trafficked pages. My gut is that I will need to offload the statistics calculation to either couch or run the stats in advance of when they are called, but I am not sure. Lastly: Like I mentioned above, one of the primary reasons for using couch is to allow users to define their own things to track per trade. Getting the data into couch is no problem, but how would I be able to take the custom_tracking array and find how many winning trades for each named tracking attribute. If anyone can give me any hints to the possibility of doing this that would be great. Thanks a bunch. Would really appreciate any help. Willing to fork out some $$$ if someone wants to take on the problem for me. (Don't know if that is allowed on stack overflow or not.)

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  • MySQL Config File for Large System

    - by Jonathon
    We are running MySQL on a Windows 2003 Server Enterpise Edition box. MySQL is about the only program running on the box. We have approx. 8 slaves replicated to it, but my understanding is that having multiple slaves connecting to the same master does not significantly slow down performance, if at all. The master server has 16G RAM, 10 Terabyte drives in RAID 10, and four dual-core processors. From what I have seen from other sites, we have a really robust machine as our master db server. We just upgraded from a machine with only 4G RAM, but with similar hard drives, RAID, etc. It also ran Apache on it, so it was our db server and our application server. It was getting a little slow, so we split the db server onto this new machine and kept the application server on the first machine. We also distributed the application load amongst a few of our other slave servers, which also run the application. The problem is the new db server has mysqld.exe consuming 95-100% of CPU almost all the time and is really causing the app to run slowly. I know we have several queries and table structures that could be better optimized, but since they worked okay on the older, smaller server, I assume that our my.ini (MySQL config) file is not properly configured. Most of what I see on the net is for setting config files on small machines, so can anyone help me get the my.ini file correct for a large dedicated machine like ours? I just don't see how mysqld could get so bogged down! FYI: We have about 100 queries per second. We only use MyISAM tables, so skip-innodb is set in the ini file. And yes, I know it is reading the ini file correctly because I can change some settings (like the server-id and it will kill the server at startup). Here is the my.ini file: #MySQL Server Instance Configuration File # ---------------------------------------------------------------------- # Generated by the MySQL Server Instance Configuration Wizard # # # Installation Instructions # ---------------------------------------------------------------------- # # On Linux you can copy this file to /etc/my.cnf to set global options, # mysql-data-dir/my.cnf to set server-specific options # (@localstatedir@ for this installation) or to # ~/.my.cnf to set user-specific options. # # On Windows you should keep this file in the installation directory # of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To # make sure the server reads the config file use the startup option # "--defaults-file". # # To run run the server from the command line, execute this in a # command line shell, e.g. # mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # To install the server as a Windows service manually, execute this in a # command line shell, e.g. # mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # And then execute this in a command line shell to start the server, e.g. # net start MySQLXY # # # Guildlines for editing this file # ---------------------------------------------------------------------- # # In this file, you can use all long options that the program supports. # If you want to know the options a program supports, start the program # with the "--help" option. # # More detailed information about the individual options can also be # found in the manual. # # # CLIENT SECTION # ---------------------------------------------------------------------- # # The following options will be read by MySQL client applications. # Note that only client applications shipped by MySQL are guaranteed # to read this section. If you want your own MySQL client program to # honor these values, you need to specify it as an option during the # MySQL client library initialization. # [client] port=3306 [mysql] default-character-set=latin1 # SERVER SECTION # ---------------------------------------------------------------------- # # The following options will be read by the MySQL Server. Make sure that # you have installed the server correctly (see above) so it reads this # file. # [mysqld] # The TCP/IP Port the MySQL Server will listen on port=3306 #Path to installation directory. All paths are usually resolved relative to this. basedir="D:/MySQL/" #Path to the database root datadir="D:/MySQL/data" # The default character set that will be used when a new schema or table is # created and no character set is defined default-character-set=latin1 # The default storage engine that will be used when create new tables when default-storage-engine=MYISAM # Set the SQL mode to strict #sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" # we changed this because there are a couple of queries that can get blocked otherwise sql-mode="" #performance configs skip-locking max_allowed_packet = 1M table_open_cache = 512 # The maximum amount of concurrent sessions the MySQL server will # allow. One of these connections will be reserved for a user with # SUPER privileges to allow the administrator to login even if the # connection limit has been reached. max_connections=1510 # Query cache is used to cache SELECT results and later return them # without actual executing the same query once again. Having the query # cache enabled may result in significant speed improvements, if your # have a lot of identical queries and rarely changing tables. See the # "Qcache_lowmem_prunes" status variable to check if the current value # is high enough for your load. # Note: In case your tables change very often or if your queries are # textually different every time, the query cache may result in a # slowdown instead of a performance improvement. query_cache_size=168M # The number of open tables for all threads. Increasing this value # increases the number of file descriptors that mysqld requires. # Therefore you have to make sure to set the amount of open files # allowed to at least 4096 in the variable "open-files-limit" in # section [mysqld_safe] table_cache=3020 # Maximum size for internal (in-memory) temporary tables. If a table # grows larger than this value, it is automatically converted to disk # based table This limitation is for a single table. There can be many # of them. tmp_table_size=30M # How many threads we should keep in a cache for reuse. When a client # disconnects, the client's threads are put in the cache if there aren't # more than thread_cache_size threads from before. This greatly reduces # the amount of thread creations needed if you have a lot of new # connections. (Normally this doesn't give a notable performance # improvement if you have a good thread implementation.) thread_cache_size=64 #*** MyISAM Specific options # The maximum size of the temporary file MySQL is allowed to use while # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE. # If the file-size would be bigger than this, the index will be created # through the key cache (which is slower). myisam_max_sort_file_size=100G # If the temporary file used for fast index creation would be bigger # than using the key cache by the amount specified here, then prefer the # key cache method. This is mainly used to force long character keys in # large tables to use the slower key cache method to create the index. myisam_sort_buffer_size=64M # Size of the Key Buffer, used to cache index blocks for MyISAM tables. # Do not set it larger than 30% of your available memory, as some memory # is also required by the OS to cache rows. Even if you're not using # MyISAM tables, you should still set it to 8-64M as it will also be # used for internal temporary disk tables. key_buffer_size=3072M # Size of the buffer used for doing full table scans of MyISAM tables. # Allocated per thread, if a full scan is needed. read_buffer_size=2M read_rnd_buffer_size=8M # This buffer is allocated when MySQL needs to rebuild the index in # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE # into an empty table. It is allocated per thread so be careful with # large settings. sort_buffer_size=2M #*** INNODB Specific options *** innodb_data_home_dir="D:/MySQL InnoDB Datafiles/" # Use this option if you have a MySQL server with InnoDB support enabled # but you do not plan to use it. This will save memory and disk space # and speed up some things. skip-innodb # Additional memory pool that is used by InnoDB to store metadata # information. If InnoDB requires more memory for this purpose it will # start to allocate it from the OS. As this is fast enough on most # recent operating systems, you normally do not need to change this # value. SHOW INNODB STATUS will display the current amount used. innodb_additional_mem_pool_size=11M # If set to 1, InnoDB will flush (fsync) the transaction logs to the # disk at each commit, which offers full ACID behavior. If you are # willing to compromise this safety, and you are running small # transactions, you may set this to 0 or 2 to reduce disk I/O to the # logs. Value 0 means that the log is only written to the log file and # the log file flushed to disk approximately once per second. Value 2 # means the log is written to the log file at each commit, but the log # file is only flushed to disk approximately once per second. innodb_flush_log_at_trx_commit=1 # The size of the buffer InnoDB uses for buffering log data. As soon as # it is full, InnoDB will have to flush it to disk. As it is flushed # once per second anyway, it does not make sense to have it very large # (even with long transactions). innodb_log_buffer_size=6M # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and # row data. The bigger you set this the less disk I/O is needed to # access data in tables. On a dedicated database server you may set this # parameter up to 80% of the machine physical memory size. Do not set it # too large, though, because competition of the physical memory may # cause paging in the operating system. Note that on 32bit systems you # might be limited to 2-3.5G of user level memory per process, so do not # set it too high. innodb_buffer_pool_size=500M # Size of each log file in a log group. You should set the combined size # of log files to about 25%-100% of your buffer pool size to avoid # unneeded buffer pool flush activity on log file overwrite. However, # note that a larger logfile size will increase the time needed for the # recovery process. innodb_log_file_size=100M # Number of threads allowed inside the InnoDB kernel. The optimal value # depends highly on the application, hardware as well as the OS # scheduler properties. A too high value may lead to thread thrashing. innodb_thread_concurrency=10 #replication settings (this is the master) log-bin=log server-id = 1 Thanks for all the help. It is greatly appreciated.

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  • Error when Eclipse started and now my package explorer is empty!

    - by carpenteri
    Friends, Just a quick introduction, I'm currently learning Java, using a combination of the Head First Java book and Eclipse. Everything was going well until tonight! When I started up Eclipse tonight, I saw an error message which I didn't pay attention to (I know! I know!) and acknowledged after which the project explorer was empty where it used to contain my Head First project! After a quick "google" I found the workspace.metadata.log and the errors are shown below. The version of Eclipse I am using is: 20100218-1602 and the only plugin that I use is egit. Any help would be much appreciated. Thanks !SESSION 2010-06-08 19:24:33.841 ----------------------------------------------- eclipse.buildId=unknown java.version=1.5.0_22 java.vendor=Sun Microsystems Inc. BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_GB Framework arguments: -product org.eclipse.epp.package.java.product Command-line arguments: -os win32 -ws win32 -arch x86 -product org.eclipse.epp.package.java.product !ENTRY org.eclipse.ui.workbench 4 2 2010-06-08 19:24:36.475 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.ui.workbench". !STACK 1 org.eclipse.ui.WorkbenchException: Content is not allowed in prolog. at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:121) at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:64) at org.eclipse.ui.internal.Workbench$49.run(Workbench.java:1895) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.ui.internal.Workbench.restoreState(Workbench.java:1890) at org.eclipse.ui.internal.WorkbenchConfigurer.restoreState(WorkbenchConfigurer.java:183) at org.eclipse.ui.application.WorkbenchAdvisor$1.run(WorkbenchAdvisor.java:781) Caused by: org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:94) ... 6 more !SUBENTRY 1 org.eclipse.ui 4 0 2010-06-08 19:24:36.475 !MESSAGE Content is not allowed in prolog. !STACK 0 org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:94) at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:64) at org.eclipse.ui.internal.Workbench$49.run(Workbench.java:1895) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.ui.internal.Workbench.restoreState(Workbench.java:1890) at org.eclipse.ui.internal.WorkbenchConfigurer.restoreState(WorkbenchConfigurer.java:183) at org.eclipse.ui.application.WorkbenchAdvisor$1.run(WorkbenchAdvisor.java:781) !SUBENTRY 1 org.eclipse.ui 4 0 2010-06-08 19:24:36.475 !MESSAGE Content is not allowed in prolog. !STACK 0 org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:94) at org.eclipse.ui.XMLMemento.createReadRoot(XMLMemento.java:64) at org.eclipse.ui.internal.Workbench$49.run(Workbench.java:1895) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.ui.internal.Workbench.restoreState(Workbench.java:1890) at org.eclipse.ui.internal.WorkbenchConfigurer.restoreState(WorkbenchConfigurer.java:183) at org.eclipse.ui.application.WorkbenchAdvisor$1.run(WorkbenchAdvisor.java:781) !ENTRY org.eclipse.jdt.ui 4 10001 2010-06-08 19:24:41.442 !MESSAGE Internal Error !STACK 1 org.eclipse.jdt.internal.ui.JavaUIException: Problems reading information from XML 'OpenTypeHistory.xml' at org.eclipse.jdt.internal.corext.util.History.createException(History.java:70) at org.eclipse.jdt.internal.corext.util.History.load(History.java:257) at org.eclipse.jdt.internal.corext.util.History.load(History.java:166) at org.eclipse.jdt.internal.corext.util.OpenTypeHistory.<init>(OpenTypeHistory.java:199) at org.eclipse.jdt.internal.corext.util.OpenTypeHistory.getInstance(OpenTypeHistory.java:185) at org.eclipse.jdt.internal.ui.JavaPlugin.initializeAfterLoad(JavaPlugin.java:381) at org.eclipse.jdt.internal.ui.InitializeAfterLoadJob$RealJob.run(InitializeAfterLoadJob.java:36) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.jdt.internal.corext.util.History.load(History.java:255) ... 6 more !SUBENTRY 1 org.eclipse.jdt.ui 4 4 2010-06-08 19:24:41.442 !MESSAGE Problems reading information from XML 'OpenTypeHistory.xml' !STACK 0 org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.jdt.internal.corext.util.History.load(History.java:255) at org.eclipse.jdt.internal.corext.util.History.load(History.java:166) at org.eclipse.jdt.internal.corext.util.OpenTypeHistory.<init>(OpenTypeHistory.java:199) at org.eclipse.jdt.internal.corext.util.OpenTypeHistory.getInstance(OpenTypeHistory.java:185) at org.eclipse.jdt.internal.ui.JavaPlugin.initializeAfterLoad(JavaPlugin.java:381) at org.eclipse.jdt.internal.ui.InitializeAfterLoadJob$RealJob.run(InitializeAfterLoadJob.java:36) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) !ENTRY org.eclipse.jdt.ui 4 10001 2010-06-08 19:24:50.435 !MESSAGE Internal Error !STACK 1 org.eclipse.jdt.internal.ui.JavaUIException: Problems reading information from XML 'QualifiedTypeNameHistory.xml' at org.eclipse.jdt.internal.corext.util.History.createException(History.java:70) at org.eclipse.jdt.internal.corext.util.History.load(History.java:257) at org.eclipse.jdt.internal.corext.util.History.load(History.java:166) at org.eclipse.jdt.internal.corext.util.QualifiedTypeNameHistory.<init>(QualifiedTypeNameHistory.java:33) at org.eclipse.jdt.internal.corext.util.QualifiedTypeNameHistory.getDefault(QualifiedTypeNameHistory.java:26) at org.eclipse.jdt.internal.ui.JavaPlugin.stop(JavaPlugin.java:602) at org.eclipse.osgi.framework.internal.core.BundleContextImpl$2.run(BundleContextImpl.java:843) at java.security.AccessController.doPrivileged(Native Method) at org.eclipse.osgi.framework.internal.core.BundleContextImpl.stop(BundleContextImpl.java:836) at org.eclipse.osgi.framework.internal.core.BundleHost.stopWorker(BundleHost.java:474) at org.eclipse.osgi.framework.internal.core.AbstractBundle.suspend(AbstractBundle.java:546) at org.eclipse.osgi.framework.internal.core.Framework.suspendBundle(Framework.java:1098) at org.eclipse.osgi.framework.internal.core.StartLevelManager.decFWSL(StartLevelManager.java:593) at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:261) at org.eclipse.osgi.framework.internal.core.StartLevelManager.shutdown(StartLevelManager.java:216) at org.eclipse.osgi.framework.internal.core.InternalSystemBundle.suspend(InternalSystemBundle.java:266) at org.eclipse.osgi.framework.internal.core.Framework.shutdown(Framework.java:685) at org.eclipse.osgi.framework.internal.core.Framework.close(Framework.java:583) at org.eclipse.core.runtime.adaptor.EclipseStarter.shutdown(EclipseStarter.java:409) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:200) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:592) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514) at org.eclipse.equinox.launcher.Main.run(Main.java:1311) Caused by: org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.jdt.internal.corext.util.History.load(History.java:255) ... 25 more !SUBENTRY 1 org.eclipse.jdt.ui 4 4 2010-06-08 19:24:50.435 !MESSAGE Problems reading information from XML 'QualifiedTypeNameHistory.xml' !STACK 0 org.xml.sax.SAXParseException: Content is not allowed in prolog. at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264) at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292) at org.eclipse.jdt.internal.corext.util.History.load(History.java:255) at org.eclipse.jdt.internal.corext.util.History.load(History.java:166) at org.eclipse.jdt.internal.corext.util.QualifiedTypeNameHistory.<init>(QualifiedTypeNameHistory.java:33) at org.eclipse.jdt.internal.corext.util.QualifiedTypeNameHistory.getDefault(QualifiedTypeNameHistory.java:26) at org.eclipse.jdt.internal.ui.JavaPlugin.stop(JavaPlugin.java:602) at org.eclipse.osgi.framework.internal.core.BundleContextImpl$2.run(BundleContextImpl.java:843) at java.security.AccessController.doPrivileged(Native Method) at org.eclipse.osgi.framework.internal.core.BundleContextImpl.stop(BundleContextImpl.java:836) at org.eclipse.osgi.framework.internal.core.BundleHost.stopWorker(BundleHost.java:474) at org.eclipse.osgi.framework.internal.core.AbstractBundle.suspend(AbstractBundle.java:546) at org.eclipse.osgi.framework.internal.core.Framework.suspendBundle(Framework.java:1098) at org.eclipse.osgi.framework.internal.core.StartLevelManager.decFWSL(StartLevelManager.java:593) at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:261) at org.eclipse.osgi.framework.internal.core.StartLevelManager.shutdown(StartLevelManager.java:216) at org.eclipse.osgi.framework.internal.core.InternalSystemBundle.suspend(InternalSystemBundle.java:266) at org.eclipse.osgi.framework.internal.core.Framework.shutdown(Framework.java:685) at org.eclipse.osgi.framework.internal.core.Framework.close(Framework.java:583) at org.eclipse.core.runtime.adaptor.EclipseStarter.shutdown(EclipseStarter.java:409) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:200) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:592) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514) at org.eclipse.equinox.launcher.Main.run(Main.java:1311)

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  • i am using winsock2.h in c language the following errors are unuderstandable help required?

    - by moon
    i am going to paste here my code an errors :::: #include "stdio.h" #include "winsock2.h" #define SIO_RCVALL _WSAIOW(IOC_VENDOR,1) //this removes the need of mstcpip.h void StartSniffing (SOCKET Sock); //This will sniff here and there void ProcessPacket (unsigned char* , int); //This will decide how to digest void PrintIpHeader (unsigned char* , int); void PrintUdpPacket (unsigned char* , int); void ConvertToHex (unsigned char* , unsigned int); void PrintData (unsigned char* , int); //IP Header Structure typedef struct ip_hdr { unsigned char ip_header_len:4; // 4-bit header length (in 32-bit words) normally=5 (Means 20 Bytes may be 24 also) unsigned char ip_version :4; // 4-bit IPv4 version unsigned char ip_tos; // IP type of service unsigned short ip_total_length; // Total length unsigned short ip_id; // Unique identifier unsigned char ip_frag_offset :5; // Fragment offset field unsigned char ip_more_fragment :1; unsigned char ip_dont_fragment :1; unsigned char ip_reserved_zero :1; unsigned char ip_frag_offset1; //fragment offset unsigned char ip_ttl; // Time to live unsigned char ip_protocol; // Protocol(TCP,UDP etc) unsigned short ip_checksum; // IP checksum unsigned int ip_srcaddr; // Source address unsigned int ip_destaddr; // Source address } IPV4_HDR; //UDP Header Structure typedef struct udp_hdr { unsigned short source_port; // Source port no. unsigned short dest_port; // Dest. port no. unsigned short udp_length; // Udp packet length unsigned short udp_checksum; // Udp checksum (optional) } UDP_HDR; //ICMP Header Structure typedef struct icmp_hdr { BYTE type; // ICMP Error type BYTE code; // Type sub code USHORT checksum; USHORT id; USHORT seq; } ICMP_HDR; FILE *logfile; int tcp=0,udp=0,icmp=0,others=0,igmp=0,total=0,i,j; struct sockaddr_in source,dest; char hex[2]; //Its free! IPV4_HDR *iphdr; UDP_HDR *udpheader; int main() { SOCKET sniffer; struct in_addr addr; int in; char hostname[100]; struct hostent *local; WSADATA wsa; //logfile=fopen("log.txt","w"); //if(logfile==NULL) printf("Unable to create file."); //Initialise Winsock printf("\nInitialising Winsock..."); if (WSAStartup(MAKEWORD(2,2), &wsa) != 0) { printf("WSAStartup() failed.\n"); return 1; } printf("Initialised"); //Create a RAW Socket printf("\nCreating RAW Socket..."); sniffer = socket(AF_INET, SOCK_RAW, IPPROTO_IP); if (sniffer == INVALID_SOCKET) { printf("Failed to create raw socket.\n"); return 1; } printf("Created."); //Retrive the local hostname if (gethostname(hostname, sizeof(hostname)) == SOCKET_ERROR) { printf("Error : %d",WSAGetLastError()); return 1; } printf("\nHost name : %s \n",hostname); //Retrive the available IPs of the local host local = gethostbyname(hostname); printf("\nAvailable Network Interfaces : \n"); if (local == NULL) { printf("Error : %d.\n",WSAGetLastError()); return 1; } for (i = 0; local->h_addr_list[i] != 0; ++i) { memcpy(&addr, local->h_addr_list[i], sizeof(struct in_addr)); printf("Interface Number : %d Address : %s\n",i,inet_ntoa(addr)); } printf("Enter the interface number you would like to sniff : "); scanf("%d",&in); memset(&dest, 0, sizeof(dest)); memcpy(&dest.sin_addr.s_addr,local->h_addr_list[in],sizeof(dest.sin_addr.s_addr)); dest.sin_family = AF_INET; dest.sin_port = 0; printf("\nBinding socket to local system and port 0 ..."); if (bind(sniffer,(struct sockaddr *)&dest,sizeof(dest)) == SOCKET_ERROR) { printf("bind(%s) failed.\n", inet_ntoa(addr)); return 1; } printf("Binding successful"); //Enable this socket with the power to sniff : SIO_RCVALL is the key Receive ALL ;) j=1; printf("\nSetting socket to sniff..."); if (WSAIoctl(sniffer, SIO_RCVALL,&j, sizeof(j), 0, 0,(LPDWORD)&in,0, 0) == SOCKET_ERROR) { printf("WSAIoctl() failed.\n"); return 1; } printf("Socket set."); //Begin printf("\nStarted Sniffing\n"); printf("Packet Capture Statistics...\n"); StartSniffing(sniffer); //Happy Sniffing //End closesocket(sniffer); WSACleanup(); return 0; } void StartSniffing(SOCKET sniffer) { unsigned char *Buffer = ( unsigned char *)malloc(65536); //Its Big! int mangobyte; if (Buffer == NULL) { printf("malloc() failed.\n"); return; } do { mangobyte = recvfrom(sniffer,(char *)Buffer,65536,0,0,0); //Eat as much as u can if(mangobyte > 0) ProcessPacket(Buffer, mangobyte); else printf( "recvfrom() failed.\n"); } while (mangobyte > 0); free(Buffer); } void ProcessPacket(unsigned char* Buffer, int Size) { iphdr = (IPV4_HDR *)Buffer; ++total; switch (iphdr->ip_protocol) //Check the Protocol and do accordingly... { case 1: //ICMP Protocol ++icmp; //PrintIcmpPacket(Buffer,Size); break; case 2: //IGMP Protocol ++igmp; break; case 6: //TCP Protocol ++tcp; //PrintTcpPacket(Buffer,Size); break; case 17: //UDP Protocol ++udp; PrintUdpPacket(Buffer,Size); break; default: //Some Other Protocol like ARP etc. ++others; break; } printf("TCP : %d UDP : %d ICMP : %d IGMP : %d Others : %d Total : %d\r",tcp,udp,icmp,igmp,others,total); } void PrintIpHeader (unsigned char* Buffer, int Size) { unsigned short iphdrlen; iphdr = (IPV4_HDR *)Buffer; iphdrlen = iphdr->ip_header_len*4; memset(&source, 0, sizeof(source)); source.sin_addr.s_addr = iphdr->ip_srcaddr; memset(&dest, 0, sizeof(dest)); dest.sin_addr.s_addr = iphdr->ip_destaddr; fprintf(logfile,"\n"); fprintf(logfile,"IP Header\n"); fprintf(logfile," |-IP Version : %d\n",(unsigned int)iphdr->ip_version); fprintf(logfile," |-IP Header Length : %d DWORDS or %d Bytes\n",(unsigned int)iphdr->ip_header_len); fprintf(logfile," |-Type Of Service : %d\n",(unsigned int)iphdr->ip_tos); fprintf(logfile," |-IP Total Length : %d Bytes(Size of Packet)\n",ntohs(iphdr->ip_total_length)); fprintf(logfile," |-Identification : %d\n",ntohs(iphdr->ip_id)); fprintf(logfile," |-Reserved ZERO Field : %d\n",(unsigned int)iphdr->ip_reserved_zero); fprintf(logfile," |-Dont Fragment Field : %d\n",(unsigned int)iphdr->ip_dont_fragment); fprintf(logfile," |-More Fragment Field : %d\n",(unsigned int)iphdr->ip_more_fragment); fprintf(logfile," |-TTL : %d\n",(unsigned int)iphdr->ip_ttl); fprintf(logfile," |-Protocol : %d\n",(unsigned int)iphdr->ip_protocol); fprintf(logfile," |-Checksum : %d\n",ntohs(iphdr->ip_checksum)); fprintf(logfile," |-Source IP : %s\n",inet_ntoa(source.sin_addr)); fprintf(logfile," |-Destination IP : %s\n",inet_ntoa(dest.sin_addr)); } void PrintUdpPacket(unsigned char *Buffer,int Size) { unsigned short iphdrlen; iphdr = (IPV4_HDR *)Buffer; iphdrlen = iphdr->ip_header_len*4; udpheader = (UDP_HDR *)(Buffer + iphdrlen); fprintf(logfile,"\n\n***********************UDP Packet*************************\n"); PrintIpHeader(Buffer,Size); fprintf(logfile,"\nUDP Header\n"); fprintf(logfile," |-Source Port : %d\n",ntohs(udpheader->source_port)); fprintf(logfile," |-Destination Port : %d\n",ntohs(udpheader->dest_port)); fprintf(logfile," |-UDP Length : %d\n",ntohs(udpheader->udp_length)); fprintf(logfile," |-UDP Checksum : %d\n",ntohs(udpheader->udp_checksum)); fprintf(logfile,"\n"); fprintf(logfile,"IP Header\n"); PrintData(Buffer,iphdrlen); fprintf(logfile,"UDP Header\n"); PrintData(Buffer+iphdrlen,sizeof(UDP_HDR)); fprintf(logfile,"Data Payload\n"); PrintData(Buffer+iphdrlen+sizeof(UDP_HDR) ,(Size - sizeof(UDP_HDR) - iphdr->ip_header_len*4)); fprintf(logfile,"\n###########################################################"); } void PrintData (unsigned char* data , int Size) { for(i=0 ; i < Size ; i++) { if( i!=0 && i%16==0) //if one line of hex printing is complete... { fprintf(logfile," "); for(j=i-16 ; j<i ; j++) { if(data[j]>=32 && data[j]<=128) fprintf(logfile,"%c",(unsigned char)data[j]); //if its a number or alphabet else fprintf(logfile,"."); //otherwise print a dot } fprintf(logfile,"\n"); } if(i%16==0) fprintf(logfile," "); fprintf(logfile," %02X",(unsigned int)data[i]); if( i==Size-1) //print the last spaces { for(j=0;j<15-i%16;j++) fprintf(logfile," "); //extra spaces fprintf(logfile," "); for(j=i-i%16 ; j<=i ; j++) { if(data[j]>=32 && data[j]<=128) fprintf(logfile,"%c",(unsigned char)data[j]); else fprintf(logfile,"."); } fprintf(logfile,"\n"); } } } following are the errors Error 1 error LNK2019: unresolved external symbol __imp__WSACleanup@0 referenced in function _main sniffer.obj sniffer test Error 2 error LNK2019: unresolved external symbol __imp__closesocket@4 referenced in function _main sniffer.obj sniffer test Error 3 error LNK2019: unresolved external symbol __imp__WSAIoctl@36 referenced in function _main sniffer.obj sniffer test Error 4 error LNK2019: unresolved external symbol __imp__bind@12 referenced in function _main sniffer.obj sniffer test Error 5 error LNK2019: unresolved external symbol __imp__inet_ntoa@4 referenced in function _main sniffer.obj sniffer test Error 6 error LNK2019: unresolved external symbol __imp__gethostbyname@4 referenced in function _main sniffer.obj sniffer test Error 7 error LNK2019: unresolved external symbol __imp__WSAGetLastError@0 referenced in function _main sniffer.obj sniffer test Error 8 error LNK2019: unresolved external symbol __imp__gethostname@8 referenced in function _main sniffer.obj sniffer test Error 9 error LNK2019: unresolved external symbol __imp__socket@12 referenced in function _main sniffer.obj sniffer test Error 10 error LNK2019: unresolved external symbol __imp__WSAStartup@8 referenced in function _main sniffer.obj sniffer test Error 11 error LNK2019: unresolved external symbol __imp__recvfrom@24 referenced in function "void __cdecl StartSniffing(unsigned int)" (?StartSniffing@@YAXI@Z) sniffer.obj sniffer test Error 12 error LNK2019: unresolved external symbol __imp__ntohs@4 referenced in function "void __cdecl PrintIpHeader(unsigned char *,int)" (?PrintIpHeader@@YAXPAEH@Z) sniffer.obj sniffer test Error 13 fatal error LNK1120: 12 unresolved externals E:\CWM\sniffer test\Debug\sniffer test.exe sniffer test

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  • Hi, I have a C hashing routine which is behaving strangely?

    - by aks
    Hi, In this hashing routine: 1.) I am able to add strings. 2.) I am able to view my added strings. 3.) When i try to add a duplicate string, it throws me an error saying already present. 4.) But, when i try to delete the same string which is already present in hash table, then the lookup_routine calls hash function to get an index. At this time, it throws a different hash index to the one it was already added. Hence, my delete routine is failing? I am able to understand the reason why for same string, hash fucntion calculates a different index each time (whereas the same logic works in view hash table routine)? Can someone help me? This is the Output, i am getting: $ ./a Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 1 Please enter the string :gaura enters in add_string DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 1 hashval = 1 enters in lookup_string str in lookup_string = gaura DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 1 hashval = 1 DEBUG ERROR :element not found in lookup string DEBUG Purpose NULL Inserting... DEBUG1 : enters here hashval = 1 String added successfully Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 1 Please enter the string :ayu enters in add_string DEBUG purpose in hash function: str passed = ayu Hashval returned in hash func= 1 hashval = 1 enters in lookup_string str in lookup_string = ayu DEBUG purpose in hash function: str passed = ayu Hashval returned in hash func= 1 hashval = 1 returns NULL in lookup_string DEBUG Purpose NULL Inserting... DEBUG2 : enters here hashval = 1 String added successfully Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 1 Please enter the string :gaurava enters in add_string DEBUG purpose in hash function: str passed = gaurava Hashval returned in hash func= 7 hashval = 7 enters in lookup_string str in lookup_string = gaurava DEBUG purpose in hash function: str passed = gaurava Hashval returned in hash func= 7 hashval = 7 DEBUG ERROR :element not found in lookup string DEBUG Purpose NULL Inserting... DEBUG1 : enters here hashval = 7 String added successfully Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 4 Index : i = 1 String = gaura ayu Index : i = 7 String = gaurava Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 2 Please enter the string you want to delete :gaura String entered = gaura enters in delete_string DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 0 hashval = 0 enters in lookup_string str in lookup_string = gaura DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 0 hashval = 0 DEBUG ERROR :element not found in lookup string DEBUG Purpose Item not present. So, cannot be deleted Item found in list: Deletion failed Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: My routine is pasted below: include include struct list { char *string; struct list *next; }; struct hash_table { int size; /* the size of the table */ struct list *table; / the table elements */ }; struct hash_table * hashtable = NULL; struct hash_table *create_hash_table(int size) { struct hash_table *new_table; int i; if (size<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the table structure */ if ((new_table = malloc(sizeof(struct hash_table))) == NULL) { return NULL; } /* Attempt to allocate memory for the table itself */ if ((new_table->table = malloc(sizeof(struct list *) * size)) == NULL) { return NULL; } /* Initialize the elements of the table */ for(i=0; i<size; i++) new_table->table[i] = '\0'; /* Set the table's size */ new_table->size = size; return new_table; } unsigned int hash(struct hash_table *hashtable, char *str) { printf("\n DEBUG purpose in hash function:\n"); printf("\n str passed = %s", str); unsigned int hashval = 0; int i = 0; for(; *str != '\0'; str++) { hashval += str[i]; i++; } hashval = hashval % 10; printf("\n Hashval returned in hash func= %d", hashval); return hashval; } struct list *lookup_string(struct hash_table *hashtable, char *str) { printf("\n enters in lookup_string \n"); printf("\n str in lookup_string = %s",str); struct list * new_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d \n", hashval); if(hashtable->table[hashval] == NULL) { printf("\n DEBUG ERROR :element not found in lookup string \n"); return NULL; } /* Go to the correct list based on the hash value and see if str is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ for(new_list = hashtable->table[hashval]; new_list != NULL;new_list = new_list->next) { if (strcmp(str, new_list->string) == 0) return new_list; } printf("\n returns NULL in lookup_string \n"); return NULL; } int add_string(struct hash_table *hashtable, char *str) { printf("\n enters in add_string \n"); struct list *new_list; struct list *current_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d", hashval); /* Attempt to allocate memory for list */ if ((new_list = malloc(sizeof(struct list))) == NULL) { printf("\n enters here \n"); return 1; } /* Does item already exist? */ current_list = lookup_string(hashtable, str); if (current_list == NULL) { printf("\n DEBUG Purpose \n"); printf("\n NULL \n"); } /* item already exists, don't insert it again. */ if (current_list != NULL) { printf("\n Item already present...\n"); return 2; } /* Insert into list */ printf("\n Inserting...\n"); new_list->string = strdup(str); new_list->next = NULL; //new_list->next = hashtable->table[hashval]; if(hashtable->table[hashval] == NULL) { printf("\n DEBUG1 : enters here \n"); printf("\n hashval = %d", hashval); hashtable->table[hashval] = new_list; } else { printf("\n DEBUG2 : enters here \n"); printf("\n hashval = %d", hashval); struct list * temp_list = hashtable->table[hashval]; while(temp_list->next!=NULL) temp_list = temp_list->next; temp_list->next = new_list; // hashtable->table[hashval] = new_list; } return 0; } int delete_string(struct hash_table *hashtable, char *str) { printf("\n enters in delete_string \n"); struct list *new_list; struct list *current_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d", hashval); /* Does item already exist? */ current_list = lookup_string(hashtable, str); if (current_list == NULL) { printf("\n DEBUG Purpose \n"); printf("\n Item not present. So, cannot be deleted \n"); return 1; } /* item exists, delete it. */ if (current_list != NULL) { struct list * temp = hashtable->table[hashval]; if(strcmp(temp->string,str) == 0) { if(temp->next == NULL) { hashtable->table[hashval] = NULL; free(temp); } else { hashtable->table[hashval] = temp->next; free(temp); } } else { struct list * temp1; while(temp->next != NULL) { temp1 = temp; if(strcmp(temp->string, str) == 0) { break; } else { temp = temp->next; } } if(temp->next == NULL) { temp1->next = NULL; free(temp); } else { temp1->next = temp->next; free(temp); } } } return 0; } void free_table(struct hash_table *hashtable) { int i; struct list *new_list, *temp_list; if (hashtable==NULL) return; /* Free the memory for every item in the table, including the * strings themselves. */ for(i=0; i<hashtable->size; i++) { new_list = hashtable->table[i]; while(new_list!=NULL) { temp_list = new_list; new_list = new_list->next; free(temp_list->string); free(temp_list); } } /* Free the table itself */ free(hashtable->table); free(hashtable); } void view_hashtable(struct hash_table * hashtable) { int i = 0; if(hashtable == NULL) return; for(i =0; i < hashtable->size; i++) { if((hashtable->table[i] == 0) || (strcmp(hashtable->table[i]->string, "*") == 0)) { continue; } printf(" Index : i = %d\t String = %s",i, hashtable->table[i]->string); struct list * temp = hashtable->table[i]->next; while(temp != NULL) { printf("\t %s",temp->string); temp = temp->next; } printf("\n"); } } int main() { hashtable = create_hash_table(10); if(hashtable == NULL) { printf("\n Memory allocation failure during creation of hash table \n"); return 0; } int flag = 1; while(flag) { int choice; printf("\n Press 1 to add an element to the hashtable\n"); printf("\n Press 2 to delete an element from the hashtable\n"); printf("\n Press 3 to search the hashtable\n"); printf("\n Press 4 to view the hashtable\n"); printf("\n Press 5 to exit \n"); printf("\n Please enter your choice: "); scanf("%d",&choice); if(choice == 5) flag = 0; else if(choice == 1) { char str[20]; printf("\n Please enter the string :"); scanf("%s",&str); int i; i = add_string(hashtable,str); if(i == 1) { printf("\n Memory allocation failure:Choice 1 \n"); return 0; } else if(i == 2) { printf("\n String already prsent in hash table : Couldnot add it again\n"); return 0; } else { printf("\n String added successfully \n"); } } else if(choice == 2) { int i; struct list * temp_list; char str[20]; printf("\n Please enter the string you want to delete :"); scanf("%s",&str); printf("\n String entered = %s", str); i = delete_string(hashtable,str); if(i == 0) { printf("\n Item found in list: Deletion success \n"); } else printf("\n Item found in list: Deletion failed \n"); } else if(choice == 3) { struct list * temp_list; char str[20]; printf("\n Please enter the string :"); scanf("%s",&str); temp_list = lookup_string(hashtable,str); if(!temp_list) { printf("\n Item not found in list: Deletion failed \n"); return 0; } printf("\n Item found: Present in Hash Table \n"); } else if(choice == 4) { view_hashtable(hashtable); } else if(choice == 5) { printf("\n Exiting ...."); return 0; } else printf("\n Invalid choice:"); }; free_table(hashtable); return 0; }

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  • Metro: Declarative Data Binding

    - by Stephen.Walther
    The goal of this blog post is to describe how declarative data binding works in the WinJS library. In particular, you learn how to use both the data-win-bind and data-win-bindsource attributes. You also learn how to use calculated properties and converters to format the value of a property automatically when performing data binding. By taking advantage of WinJS data binding, you can use the Model-View-ViewModel (MVVM) pattern when building Metro style applications with JavaScript. By using the MVVM pattern, you can prevent your JavaScript code from spinning into chaos. The MVVM pattern provides you with a standard pattern for organizing your JavaScript code which results in a more maintainable application. Using Declarative Bindings You can use the data-win-bind attribute with any HTML element in a page. The data-win-bind attribute enables you to bind (associate) an attribute of an HTML element to the value of a property. Imagine, for example, that you want to create a product details page. You want to show a product object in a page. In that case, you can create the following HTML page to display the product details: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1>Product Details</h1> <div class="field"> Product Name: <span data-win-bind="innerText:name"></span> </div> <div class="field"> Product Price: <span data-win-bind="innerText:price"></span> </div> <div class="field"> Product Picture: <br /> <img data-win-bind="src:photo;alt:name" /> </div> </body> </html> The HTML page above contains three data-win-bind attributes – one attribute for each product property displayed. You use the data-win-bind attribute to set properties of the HTML element associated with the data-win-attribute. The data-win-bind attribute takes a semicolon delimited list of element property names and data source property names: data-win-bind=”elementPropertyName:datasourcePropertyName; elementPropertyName:datasourcePropertyName;…” In the HTML page above, the first two data-win-bind attributes are used to set the values of the innerText property of the SPAN elements. The last data-win-bind attribute is used to set the values of the IMG element’s src and alt attributes. By the way, using data-win-bind attributes is perfectly valid HTML5. The HTML5 standard enables you to add custom attributes to an HTML document just as long as the custom attributes start with the prefix data-. So you can add custom attributes to an HTML5 document with names like data-stephen, data-funky, or data-rover-dog-is-hungry and your document will validate. The product object displayed in the page above with the data-win-bind attributes is created in the default.js file: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var product = { name: "Tesla", price: 80000, photo: "/images/TeslaPhoto.png" }; WinJS.Binding.processAll(null, product); } }; app.start(); })(); In the code above, a product object is created with a name, price, and photo property. The WinJS.Binding.processAll() method is called to perform the actual binding (Don’t confuse WinJS.Binding.processAll() and WinJS.UI.processAll() – these are different methods). The first parameter passed to the processAll() method represents the root element for the binding. In other words, binding happens on this element and its child elements. If you provide the value null, then binding happens on the entire body of the document (document.body). The second parameter represents the data context. This is the object that has the properties which are displayed with the data-win-bind attributes. In the code above, the product object is passed as the data context parameter. Another word for data context is view model.  Creating Complex View Models In the previous section, we used the data-win-bind attribute to display the properties of a simple object: a single product. However, you can use binding with more complex view models including view models which represent multiple objects. For example, the view model in the following default.js file represents both a customer and a product object. Furthermore, the customer object has a nested address object: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var viewModel = { customer: { firstName: "Fred", lastName: "Flintstone", address: { street: "1 Rocky Way", city: "Bedrock", country: "USA" } }, product: { name: "Bowling Ball", price: 34.55 } }; WinJS.Binding.processAll(null, viewModel); } }; app.start(); })(); The following page displays the customer (including the customer address) and the product. Notice that you can use dot notation to refer to child objects in a view model such as customer.address.street. <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1>Customer Details</h1> <div class="field"> First Name: <span data-win-bind="innerText:customer.firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:customer.lastName"></span> </div> <div class="field"> Address: <address> <span data-win-bind="innerText:customer.address.street"></span> <br /> <span data-win-bind="innerText:customer.address.city"></span> <br /> <span data-win-bind="innerText:customer.address.country"></span> </address> </div> <h1>Product</h1> <div class="field"> Name: <span data-win-bind="innerText:product.name"></span> </div> <div class="field"> Price: <span data-win-bind="innerText:product.price"></span> </div> </body> </html> A view model can be as complicated as you need and you can bind the view model to a view (an HTML document) by using declarative bindings. Creating Calculated Properties You might want to modify a property before displaying the property. For example, you might want to format the product price property before displaying the property. You don’t want to display the raw product price “80000”. Instead, you want to display the formatted price “$80,000”. You also might need to combine multiple properties. For example, you might need to display the customer full name by combining the values of the customer first and last name properties. In these situations, it is tempting to call a function when performing binding. For example, you could create a function named fullName() which concatenates the customer first and last name. Unfortunately, the WinJS library does not support the following syntax: <span data-win-bind=”innerText:fullName()”></span> Instead, in these situations, you should create a new property in your view model that has a getter. For example, the customer object in the following default.js file includes a property named fullName which combines the values of the firstName and lastName properties: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var customer = { firstName: "Fred", lastName: "Flintstone", get fullName() { return this.firstName + " " + this.lastName; } }; WinJS.Binding.processAll(null, customer); } }; app.start(); })(); The customer object has a firstName, lastName, and fullName property. Notice that the fullName property is defined with a getter function. When you read the fullName property, the values of the firstName and lastName properties are concatenated and returned. The following HTML page displays the fullName property in an H1 element. You can use the fullName property in a data-win-bind attribute in exactly the same way as any other property. <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1 data-win-bind="innerText:fullName"></h1> <div class="field"> First Name: <span data-win-bind="innerText:firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:lastName"></span> </div> </body> </html> Creating a Converter In the previous section, you learned how to format the value of a property by creating a property with a getter. This approach makes sense when the formatting logic is specific to a particular view model. If, on the other hand, you need to perform the same type of formatting for multiple view models then it makes more sense to create a converter function. A converter function is a function which you can apply whenever you are using the data-win-bind attribute. Imagine, for example, that you want to create a general function for displaying dates. You always want to display dates using a short format such as 12/25/1988. The following JavaScript file – named converters.js – contains a shortDate() converter: (function (WinJS) { var shortDate = WinJS.Binding.converter(function (date) { return date.getMonth() + 1 + "/" + date.getDate() + "/" + date.getFullYear(); }); // Export shortDate WinJS.Namespace.define("MyApp.Converters", { shortDate: shortDate }); })(WinJS); The file above uses the Module Pattern, a pattern which is used through the WinJS library. To learn more about the Module Pattern, see my blog entry on namespaces and modules: http://stephenwalther.com/blog/archive/2012/02/22/windows-web-applications-namespaces-and-modules.aspx The file contains the definition for a converter function named shortDate(). This function converts a JavaScript date object into a short date string such as 12/1/1988. The converter function is created with the help of the WinJS.Binding.converter() method. This method takes a normal function and converts it into a converter function. Finally, the shortDate() converter is added to the MyApp.Converters namespace. You can call the shortDate() function by calling MyApp.Converters.shortDate(). The default.js file contains the customer object that we want to bind. Notice that the customer object has a firstName, lastName, and birthday property. We will use our new shortDate() converter when displaying the customer birthday property: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { var customer = { firstName: "Fred", lastName: "Flintstone", birthday: new Date("12/1/1988") }; WinJS.Binding.processAll(null, customer); } }; app.start(); })(); We actually use our shortDate converter in the HTML document. The following HTML document displays all of the customer properties: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/converters.js"></script> </head> <body> <h1>Customer Details</h1> <div class="field"> First Name: <span data-win-bind="innerText:firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:lastName"></span> </div> <div class="field"> Birthday: <span data-win-bind="innerText:birthday MyApp.Converters.shortDate"></span> </div> </body> </html> Notice the data-win-bind attribute used to display the birthday property. It looks like this: <span data-win-bind="innerText:birthday MyApp.Converters.shortDate"></span> The shortDate converter is applied to the birthday property when the birthday property is bound to the SPAN element’s innerText property. Using data-win-bindsource Normally, you pass the view model (the data context) which you want to use with the data-win-bind attributes in a page by passing the view model to the WinJS.Binding.processAll() method like this: WinJS.Binding.processAll(null, viewModel); As an alternative, you can specify the view model declaratively in your markup by using the data-win-datasource attribute. For example, the following default.js script exposes a view model with the fully-qualified name of MyWinWebApp.viewModel: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { // Create view model var viewModel = { customer: { firstName: "Fred", lastName: "Flintstone" }, product: { name: "Bowling Ball", price: 12.99 } }; // Export view model to be seen by universe WinJS.Namespace.define("MyWinWebApp", { viewModel: viewModel }); // Process data-win-bind attributes WinJS.Binding.processAll(); } }; app.start(); })(); In the code above, a view model which represents a customer and a product is exposed as MyWinWebApp.viewModel. The following HTML page illustrates how you can use the data-win-bindsource attribute to bind to this view model: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <h1>Customer Details</h1> <div data-win-bindsource="MyWinWebApp.viewModel.customer"> <div class="field"> First Name: <span data-win-bind="innerText:firstName"></span> </div> <div class="field"> Last Name: <span data-win-bind="innerText:lastName"></span> </div> </div> <h1>Product</h1> <div data-win-bindsource="MyWinWebApp.viewModel.product"> <div class="field"> Name: <span data-win-bind="innerText:name"></span> </div> <div class="field"> Price: <span data-win-bind="innerText:price"></span> </div> </div> </body> </html> The data-win-bindsource attribute is used twice in the page above: it is used with the DIV element which contains the customer details and it is used with the DIV element which contains the product details. If an element has a data-win-bindsource attribute then all of the child elements of that element are affected. The data-win-bind attributes of all of the child elements are bound to the data source represented by the data-win-bindsource attribute. Summary The focus of this blog entry was data binding using the WinJS library. You learned how to use the data-win-bind attribute to bind the properties of an HTML element to a view model. We also discussed several advanced features of data binding. We examined how to create calculated properties by including a property with a getter in your view model. We also discussed how you can create a converter function to format the value of a view model property when binding the property. Finally, you learned how to use the data-win-bindsource attribute to specify a view model declaratively.

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