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• Usage of IcmpSendEcho2 with an asynchronous callback

  - by Ben Voigt

  I've been reading the MSDN documentation for IcmpSendEcho2 and it raises more questions than it answers. I'm familiar with asynchronous callbacks from other Win32 APIs such as ReadFileEx... I provide a buffer which I guarantee will be reserved for the driver's use until the operation completes with any result other than IO_PENDING, I get my callback in case of either success or failure (and call GetCompletionStatus to find out which). Timeouts are my responsibility and I can call CancelIo to abort processing, but the buffer is still reserved until the driver cancels the operation and calls my completion routine with a status of CANCELLED. And there's an OVERLAPPED structure which uniquely identifies the request through all of this. IcmpSendEcho2 doesn't use an OVERLAPPED context structure for asynchronous requests. And the documentation is unclear excessively minimalist about what happens if the ping times out or fails (failure would be lack of a network connection, a missing ARP entry for local peers, ICMP destination unreachable response from an intervening router for remote peers, etc). Does anyone know whether the callback occurs on timeout and/or failure? And especially, if no response comes, can I reuse the buffer for another call to IcmpSendEcho2 or is it forever reserved in case a reply comes in late? I'm wanting to use this function from a Win32 service, which means I have to get the error-handling cases right and I can't just leak buffers (or if the API does leak buffers, I have to use a helper process so I have a way to abandon requests). There's also an ugly incompatibility in the way the callback is made. It looks like the first parameter is consistent between the two signatures, so I should be able to use the newer PIO_APC_ROUTINE as long as I only use the second parameter if an OS version check returns Vista or newer? Although MSDN says "don't do a Windows version check", it seems like I need to, because the set of versions with the new argument aren't the same as the set of versions where the function exists in iphlpapi.dll. Pointers to additional documentation or working code which uses this function and an APC would be much appreciated. Please also let me know if this is completely the wrong approach -- i.e. if either using raw sockets or some combination of IcmpCreateFile+WriteFileEx+ReadFileEx would be more robust.

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• Blocking access to websites with objective-C / root privileges in objective-C

  - by kvaruni

  I am writing a program in Objective-C (XCode 3.2, on Snow Leopard) that is capable of either selectively blocking certain sites for a duration or only allow certain sites (and thus block all others) for a duration. The reasoning behind this program is rather simple. I tend to get distracted when I have full internet access, but I do need internet access during my working hours to get to a number of work-related websites. Clearly, this is not a permanent block, but only helps me to focus whenever I find myself wandering a bit too much. At the moment, I am using a Unix script that is called via AppleScript to obtain Administrator permissions. It then activates a number of ipfw rules and clears those after a specific duration to restore full internet access. Simple and effective, but since I am running as a standard user, it gets cumbersome to enter my administrator password each and every time I want to go "offline". Furthermore, this is a great opportunity to learn to work with XCode and Objective-C. At the moment, everything works as expected, minus the actual blocking. I can add a number of sites in a list, specify whether or not I want to block or allow these websites and I can "start" the blocking by specifying a time until which I want to stay "offline". However, I find it hard to obtain clear information on how I can run a privileged Unix command from Objective-C. Ideally, I would like to be able to store information with respect to the Administrator account into the Keychain to use these later on, so that I can simply move into "offline" mode with the convenience of clicking a button. Even more ideally, there might be some class in Objective-C with which I can block access to some/all websites for this particular user without needing to rely on privileged Unix commands. A third possibility is in starting this program with root permissions and the reducing the permissions until I need them, but since this is a GUI application that is nested in the menu bar of OS X, the results are rather awkward and getting it to run each and every time with root permission is no easy task. Anyone who can offer me some pointers or advice? Please, no security-warnings, I am fully aware that what I want to do is a potential security threat.

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• Tips / techniques for high-performance C# server sockets

  - by McKenzieG1

  I have a .NET 2.0 server that seems to be running into scaling problems, probably due to poor design of the socket-handling code, and I am looking for guidance on how I might redesign it to improve performance. Usage scenario: 50 - 150 clients, high rate (up to 100s / second) of small messages (10s of bytes each) to / from each client. Client connections are long-lived - typically hours. (The server is part of a trading system. The client messages are aggregated into groups to send to an exchange over a smaller number of 'outbound' socket connections, and acknowledgment messages are sent back to the clients as each group is processed by the exchange.) OS is Windows Server 2003, hardware is 2 x 4-core X5355. Current client socket design: A TcpListener spawns a thread to read each client socket as clients connect. The threads block on Socket.Receive, parsing incoming messages and inserting them into a set of queues for processing by the core server logic. Acknowledgment messages are sent back out over the client sockets using async Socket.BeginSend calls from the threads that talk to the exchange side. Observed problems: As the client count has grown (now 60-70), we have started to see intermittent delays of up to 100s of milliseconds while sending and receiving data to/from the clients. (We log timestamps for each acknowledgment message, and we can see occasional long gaps in the timestamp sequence for bunches of acks from the same group that normally go out in a few ms total.) Overall system CPU usage is low (< 10%), there is plenty of free RAM, and the core logic and the outbound (exchange-facing) side are performing fine, so the problem seems to be isolated to the client-facing socket code. There is ample network bandwidth between the server and clients (gigabit LAN), and we have ruled out network or hardware-layer problems. Any suggestions or pointers to useful resources would be greatly appreciated. If anyone has any diagnostic or debugging tips for figuring out exactly what is going wrong, those would be great as well. Note: I have the MSDN Magazine article Winsock: Get Closer to the Wire with High-Performance Sockets in .NET, and I have glanced at the Kodart "XF.Server" component - it looks sketchy at best.

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• Multiple ToggleButton image with different highlight image in WPF

  - by Ryan

  I am very new to WPF and needed some pointers as to why this is not working correctly. I am trying to make a maximize button that will change to a restore button when clicked. I thought a toggle button with 2 different styles that would be changed in the code behind could work. I am first trying to get the maximize button working and have ran into a problem. I get the error 'System.Windows.Controls.Image' is not a valid value for the 'System.Windows.Controls.Image.Source' property on a Setter. in my xaml. I seem to be not understanding something completely. Any help would be most helpful :) Ryan <Style x:Key="Maximize" TargetType="{x:Type ToggleButton}"> <Style.Resources> <Image x:Key="MaxButtonImg" Source="/Project;component/Images/maxbutton.png" /> <Image x:Key="MaxButtonHighlight" Source="/Project;component/Images/maxbutton-highlight.png" /> </Style.Resources> <Setter Property="ContentTemplate"> <Setter.Value> <Image> <Image.Style> <Style TargetType="{x:Type Image}"> <Setter Property="Source" Value="{DynamicResource MaxButtonImg}"/> <Style.Triggers> <Trigger Property="IsMouseOver" Value="True"> <Setter Property="Source" Value="{DynamicResource MaxButtonHighlight}"/> </Trigger> </Style.Triggers> </Style> </Image.Style> </Image> </Setter.Value> </Setter> </Style> <ToggleButton Name="MaxButton" Width="31" Height="31" BorderThickness="0" Click="MaxButton_Click" Margin="0,0,10,0" Tag="Max" Style="{DynamicResource Maximize}" /> My code behind would do something simple like this: private void MaxButton_Click(object sender, RoutedEventArgs e) { ToggleButton tg = (ToggleButton)sender; if ( tg.IsChecked == true) { tg.Style = (Style)FindResource("Restore"); this.WindowState = WindowState.Maximized; } else { tg.Style = (Style)FindResource("Maximize"); this.WindowState = WindowState.Normal; } }

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• jQuery Validation plugin: disable validation for specified submit buttons

  - by Ted

  I have a form with multiple fields that I'm validating (some with methods added for custom validation) with Jörn Zaeffere's excellent jQuery Validation plugin. How do you circumvent validation with specified submit controls (in other words, fire validation with some submit inputs, but do not fire validation with others)? This would be similar to ValidationGroups with standard ASP.NET validator controls. My situation: It's with ASP.NET WebForms, but you can ignore that if you wish. However, I am using the validation more as a "recommendation": in other words, when the form is submitted, validation fires but instead of a "required" message displaying, a "recommendation" shows that says something along the line of "you missed the following fields.... do you wish to proceed anyways?" At that point in the error container there's another submit button now visible that can be pressed which would ignore the validation and submit anyways. How to circumvent the forms .validate() for this button control and still post? The Buy and Sell a House sample at http://jquery.bassistance.de/validate/demo/multipart/ allows for this in order to hit the previous links, but it does so through creating custom methods and adding it to the validator. I would prefer to not have to create custom methods duplicating functionality already in the validation plugin. The following is a shortened version of the immediately applicable script that I've got right now: var container = $("#<%= Form.ClientID %> div.validationSuggestion"); $('#<%= Form.ClientID %>').validate({ errorContainer: container, errorLabelContainer: $("ul",container), rules: { <%= YesNo.UniqueID %>: { required: true }, <%= ShortText.UniqueID %>: { required: true } // etc. }, messages: { <%= YesNo.UniqueID %>: 'A message.', <%= ShortText.UniqueID %>: 'Another message.' // etc. }, highlight: function(element, errorClass) { $(element).addClass(errorClass); $(element.form).find("label[for=" + element.id + "]").addClass(errorClass); $(element.form).find("label[for=" + element.id + "]").removeClass("valid"); }, unhighlight: function(element, errorClass) { $(element).removeClass(errorClass); $(element.form).find("label[for=" + element.id + "]").removeClass(errorClass); $(element.form).find("label[for=" + element.id + "]").addClass("valid"); }, wrapper: 'li' }); Much thanks in advance for helpful pointers. [UPDATE] Thanks to redsquare I discovered it's as easy as adding class="cancel" to the submit button. So easy and yet I have no idea how I did not come across it in all my searching. And for those who say my my follow-up answer regarding "but requires a double-click": this was merely due to a leftover experiment line that was unbinding the event - again something I don't know how I overlooked when testing. Thanks!

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• Hook IDispatch v-table in C++

  - by monoceres

  I'm trying to modify the behavior of an IDispatch interface already present in the system. To do this my plan was to hook into the objects v-table during runtime and modify the pointers so it points to a custom hook method instead. If I can get this to work I can add new methods and properties to already existing objects. Nice. First I tried hooking into the v-table for IUnknown (from which IDispatch inherits from) and that worked fine. However trying to change entires in IDispatch doesn't work at all. Nothing happens at all, the code works just as it did without the hook. Here's the code, it's very simple so it shouldn't be any problems to understand #include <iostream> #include <windows.h> #include <Objbase.h> #pragma comment (lib,"Ole32.lib") using namespace std; HRESULT __stdcall typecount(IDispatch *self,UINT*u) { cout << "hook" << endl; *u=1; return S_OK; } int main() { CoInitialize(NULL); // Get clsid from name CLSID clsid; CLSIDFromProgID(L"shell.application",&clsid); // Create instance IDispatch *obj=NULL; CoCreateInstance(clsid,NULL,CLSCTX_INPROC_SERVER,__uuidof(IDispatch),(void**)&obj); // Get vtable and offset in vtable for idispatch void* iunknown_vtable= (void*)*((unsigned int*)obj); // There are three entries in IUnknown, therefore add 12 to go to IDispatch void* idispatch_vtable = (void*)(((unsigned int)iunknown_vtable)+12); // Get pointer of first emtry in IDispatch vtable (GetTypeInfoCount) unsigned int* v1 = (unsigned int*)iunknown_vtable; // Change memory permissions so address can be overwritten DWORD old; VirtualProtect(v1,4,PAGE_EXECUTE_READWRITE,&old); // Override v-table pointer *v1 = (unsigned int) typecount; // Try calling GetTypeInfo count, should now be hooked. But isn't works as usual UINT num=0; obj->GetTypeInfoCount(&num); /* HRESULT hresult; OLECHAR FAR* szMember = (OLECHAR*)L"MinimizeAll"; DISPID dispid; DISPPARAMS dispparamsNoArgs = {NULL, NULL, 0, 0}; hresult = obj->GetIDsOfNames(IID_NULL, &szMember, 1, LOCALE_SYSTEM_DEFAULT, &dispid) ; hresult = obj->Invoke(dispid,IID_NULL,LOCALE_SYSTEM_DEFAULT,DISPATCH_METHOD,&dispparamsNoArgs, NULL, NULL, NULL); */ } Thanks in advance!

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• vector iterator not dereferencable at runtime on a vector<vector<vector<A*>*>*>

  - by marouanebj

  Hi, I have this destructor that create error at runtime "vector iterator not dereferencable". The gridMatrix is a std::vector<std::vector<std::vector<AtomsCell< Atom<T> * > * > * > * > I added the typename and also the typedef but I still have the error. I will move for this idea of vect of vect* of vect* to use boost::multi_array I think, but still I want to understand were this is wrong. /// @brief destructor ~AtomsGrid(void) { // free all the memory for all the pointers inside gridMatrix (all except the Atom<T>* ) //typedef typename ::value_type value_type; typedef std::vector<AtomsCell< Atom<T>* >*> std_vectorOfAtomsCell; typedef std::vector<std_vectorOfAtomsCell*> std_vectorOfVectorOfAtomsCell; std_vectorOfAtomsCell* vectorOfAtomsCell; std_vectorOfVectorOfAtomsCell* vectorOfVecOfAtomsCell; typename std_vectorOfVectorOfAtomsCell::iterator itSecond; typename std_vectorOfVectorOfAtomsCell::reverse_iterator reverseItSecond; typename std::vector<std_vectorOfVectorOfAtomsCell*>::iterator itFirst; //typename std::vector<AtomsCell< Atom<T>* >*>* vectorOfAtomsCell; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>* vectorOfVecOfAtomsCell; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>::iterator itSecond; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>::reverse_iterator reverseItSecond; //typename std::vector<std::vector<std::vector<AtomsCell< Atom<T>* >*>*>*>::iterator itFirst; for (itFirst = gridMatrix.begin(); itFirst != gridMatrix.end(); ++itFirst) { vectorOfVecOfAtomsCell = (*itFirst); while (!vectorOfVecOfAtomsCell->empty()) { reverseItSecond = vectorOfVecOfAtomsCell->rbegin(); itSecond = vectorOfVecOfAtomsCell->rbegin().base(); vectorOfAtomsCell = (*itSecond); // ERROR during run: "vector iterator not dereferencable" // I think the ERROR is because I need some typedef typename or template ???!!! // the error seems here event at itFirst //fr_Myit_Utils::vectorElementDeleter(*vectorOfAtomsCell); //vectorOfVecOfAtomsCell->pop_back(); } } fr_Myit_Utils::vectorElementDeleter(gridMatrix); } If someone want the full code that create the error I'm happy to give it but I do not think we can attach file in the forum. BUT still its is not very big so if you want it I can copy past it here. Thanks

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• Objective-C Out of scope problem

  - by davbryn

  Hi, I'm having a few problems with some Objective-C and would appreciate some pointers. So I have a class MapFileGroup which has the following simple interface (There are other member variables but they aren't important): @interface MapFileGroup : NSObject { NSMutableArray *mapArray; } @property (nonatomic, retain) NSMutableArray *mapArray; mapArray is @synthesize'd in the .m file. It has an init method: -(MapFileGroup*) init { self = [super init]; if (self) { mapArray = [NSMutableArray arrayWithCapacity: 10]; } return self; } It also has a method for adding a custom object to the array: -(BOOL) addMapFile:(MapFile*) mapfile { if (mapfile == nil) return NO; mapArray addObject:mapfile]; return YES; } The problem I get comes when I want to use this class - obviously due to a misunderstanding of memory management on my part. In my view controller I declare as follows: (in the @interface): MapFileGroup *fullGroupOfMaps; With @property @property (nonatomic, retain) MapFileGroup *fullGroupOfMaps; Then in the .m file I have a function called loadMapData that does the following: MapFileGroup *mapContainer = [[MapFileGroup alloc] init]; // create a predicate that we can use to filter an array // for all strings ending in .png (case insensitive) NSPredicate *caseInsensitivePNGFiles = [NSPredicate predicateWithFormat:@"SELF endswith[c] '.png'"]; mapNames = [unfilteredArray filteredArrayUsingPredicate:caseInsensitivePNGFiles]; [mapNames retain]; NSEnumerator * enumerator = [mapNames objectEnumerator]; NSString * currentFileName; NSString *nameOfMap; MapFile *mapfile; while(currentFileName = [enumerator nextObject]) { nameOfMap = [currentFileName substringToIndex:[currentFileName length]-4]; //strip the extension mapfile = [[MapFile alloc] initWithName:nameOfMap]; [mapfile retain]; // add to array [fullGroupOfMaps addMapFile:mapfile]; } This seems to work ok (Though I can tell I've not got the memory management working properly, I'm still learning Objective-C); however, I have an (IBAction) that interacts with the fullGroupOfMaps later. It calls a method within fullGroupOfMaps, but if I step into the class from that line while debugging, all fullGroupOfMaps's objects are now out of scope and I get a crash. So apologies for the long question and big amount of code, but I guess my main question it: How should I handle a class with an NSMutableArray as an instance variable? What is the proper way of creating objects to be added to the class so that they don't get freed before I'm done with them? Many thanks

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• struts2 invalid.token returned when form submitted using JQuery

  - by John

  Hi, I have inherited some code in which I now have to add CSRF prevention and am trying to use the struts2 tokenSession interceptor to do this. I am adding a token to my form using the struts2 token tag like so: <form id="updateObject" name="updateObject" action="<%=request.getContextPath()%>/prv/updateObject.action" method="POST"> <fieldset class="x-fieldset"> <legend>Update object - Action Required</legend> <div>...</div> <s:token /> <s:hidden name="id" id="objectId" /> more stuff here... <input type="submit" value="Update Object" onclick="javascript:return doUpdateObject('myAction');"/> </fieldset> </form> In my javascript function, I am adding/removing some validation rules (depending upon the action required, and submitting the form: function doUpdateObject(action){ actionPanel.registerAction(action); // this function places the action name in an in-scope variable doUpdateObjectValidationSetup(action); // this function adds/removes jquery validation rules depending upon the action if($("#updateObject").valid()){ $("form#updateObject").submit(); } return false; } I have intercepted the request and a token is being added, however the struts2 tokenSession interceptor is returning invalid.token. The code works as expected without this interceptor. (struts2 xml file not posted - will post the relevant section if required). I have also used the tokenSession interceptor in other pages which use a basic html submit button (i.e. not going via javascript or jquery) and this also works as expected. What is making the token invalid? N.B. The project I have inherited uses a strange mixture of standard html, struts2 tags, ExtJS and JQuery. I will clean this up at some point but at the moment I just need to get the tokenSession interceptor working asap in the code as-is (as I have to apply a similar fix to several hundred pages...). Any help/pointers/tips/etc greatly appreciated! Regards, John

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• Access Violation Using memcpy or Assignment to an Array in a Struct

  - by Synetech inc.

  Hi, I wrote a program last night that worked just fine but when I refactored it today to make it more extensible, I ended up with a problem. The original version had a hard-coded array of bytes. After some processing, some bytes were written into the array and then some more processing was done. To avoid hard-coding the pattern, I put the array in a structure so that I could add some related data and create an array of them. However now, I cannot write to the array in the structure. Here’s a pseudo-code example: main() { char pattern[]="\x32\x33\x12\x13\xba\xbb"; PrintData(pattern); pattern[2]='\x65'; PrintData(pattern); } That one works but this one does not: struct ENTRY { char* pattern; int somenum; }; main() { ENTRY Entries[] = { {"\x32\x33\x12\x13\xba\xbb\x9a\xbc", 44} , {"\x12\x34\x56\x78", 555} }; PrintData(Entries[0].pattern); Entries[0].pattern[2]='\x65'; //0xC0000005 exception!!! :( PrintData(Entries[0].pattern); } The second version causes an access violation exception on the assignment. I’m sure it’s because the second version allocates memory differently, but I’m starting to get a headache trying to figure out what’s what or how to get fix this. (I’m currently working around it by dynamically allocating a buffer of the same size as the pattern array, copying the pattern to the new buffer, making the changes to the buffer, using the buffer in the place of the pattern array, and then trying to remember to free the—temporary—buffer.) (Specifically, the original version cast the pattern array—+offset—to a DWORD* and assigned a DWORD constant to it to overwrite the four target bytes. The new version cannot do that since the length of the source is unknown—may not be four bytes—so it uses memcpy instead. I’ve checked and re-checked and have made sure that the pointers to memcpy are correct, but I still get an access violation. I use memcpy instead of str(n)cpy because I am using plain chars (as an array of bytes), not Unicode chars and ignoring the null-terminator. Using an assignment as above causes the same problem.) Any ideas? Thanks a lot.

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• Error when logging in with Machinist in Shoulda test

  - by user303747

  I am having some trouble getting the right usage of Machinist and Shoulda in my testing. Here is my test: context "on POST method rating" do p = Product.make u = nil setup do u = login_as post :vote, :rating => 3, :id => p end should "set rating for product to 3" do assert_equal p.get_user_vote(u), 3 end And here's my blueprints: Sham.login { Faker::Internet.user_name } Sham.name { Faker::Lorem.words} Sham.email { Faker::Internet.email} Sham.body { Faker::Lorem.paragraphs(2)} User.blueprint do login password "testpass" password_confirmation { password } email end Product.blueprint do name {Sham.name} user {User.make} end And my authentication test helper: def login_as(u = nil) u ||= User.make() @controller.stubs(:current_user).returns(u) u end The error I get is: /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/validations.rb:1090:in `save_without_dirty!': Validation failed: Login has already been taken, Email has already been taken (ActiveRecord::RecordInvalid) from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/dirty.rb:87:in `save_without_transactions!' from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/transactions.rb:200:in `save!' from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction' from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/transactions.rb:182:in `transaction' from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/transactions.rb:200:in `save!' from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/transactions.rb:208:in `rollback_active_record_state!' from /home/jason/moderndarwin/vendor/rails/activerecord/lib/active_record/transactions.rb:200:in `save!' from /usr/lib/ruby/gems/1.8/gems/machinist-1.0.6/lib/machinist/active_record.rb:55:in `make' from /home/jason/moderndarwin/test/blueprints.rb:37 from /usr/lib/ruby/gems/1.8/gems/machinist-1.0.6/lib/machinist.rb:77:in `generate_attribute_value' from /usr/lib/ruby/gems/1.8/gems/machinist-1.0.6/lib/machinist.rb:46:in `method_missing' from /home/jason/moderndarwin/test/blueprints.rb:37 from /usr/lib/ruby/gems/1.8/gems/machinist-1.0.6/lib/machinist.rb:20:in `instance_eval' from /usr/lib/ruby/gems/1.8/gems/machinist-1.0.6/lib/machinist.rb:20:in `run' from /usr/lib/ruby/gems/1.8/gems/machinist-1.0.6/lib/machinist/active_record.rb:53:in `make' from ./test/functional/products_controller_test.rb:25:in `__bind_1269805681_945912' from /home/jason/moderndarwin/vendor/gems/thoughtbot-shoulda-2.10.2/lib/shoulda/context.rb:293:in `call' from /home/jason/moderndarwin/vendor/gems/thoughtbot-shoulda-2.10.2/lib/shoulda/context.rb:293:in `merge_block' from /home/jason/moderndarwin/vendor/gems/thoughtbot-shoulda-2.10.2/lib/shoulda/context.rb:288:in `initialize' from /home/jason/moderndarwin/vendor/gems/thoughtbot-shoulda-2.10.2/lib/shoulda/context.rb:169:in `new' from /home/jason/moderndarwin/vendor/gems/thoughtbot-shoulda-2.10.2/lib/shoulda/context.rb:169:in `context' from ./test/functional/products_controller_test.rb:24 I can't figure out what it is I'm doing wrong... I have tested the login_as with my auth (Authlogic) in my user_controller testing. Any pointers in the right direction would be much appreciated!

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• Fluid CSS: floating column with max-width and overflow

  - by Ates Goral

  I'm using a fluid layout in the new theme that I'm working on for my blog. I often blog about code and include <pre> blocks within the posts. The float: left column for the content area has a max-width so that the column stops at a certain maximum width and can also be shrunk: +----------+ +------+ | text | | text | | | | | | | | | | | | | | | | | | | | | +----------+ +------+ max shrunk What I want is for the <pre> elements to be wider than the text column so that I can fit 80-character-wrapped code without horizontal scroll bars. But I want the <pre> elements to overflow from the content area, without affecting its fluidity: +----------+ +------+ | text | | text | | | | | +----------+--+ +------+------+ | code | | code | +----------+--+ +------+------+ | | | | +----------+ +------+ max shrunk But, max-width stops being fluid once I insert the overhanging <pre> in there: the width of the column remains at the specified max-width even when I shrink the browser beyond that width. I've reproduced the issue with this bare-minimum scenario: <div style="float: left; max-width: 460px; border: 1px solid red"> <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit</p> <pre style="max-width: 700px; border: 1px solid blue"> function foo() { // Lorem ipsum dolor sit amet, consectetur adipisicing elit } </pre> <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit</p> </div> I noticed that doing either of the following brings back the fluidity: Remove the <pre> (doh...) Remove the float: left The workaround I'm currently using is to insert the <pre> elements into "breaks" in the post column, so that the widths of the post segments and the <pre> segments are managed mutually exclusively: +----------+ +------+ | text | | text | +----------+ +------+ +-------------+ +-------------+ | code | | code | +-------------+ +-------------+ +----------+ +------+ +----------+ +------+ max shrunk But this forces me to insert additional closing and opening <div> elements into the post markup which I'd rather keep semantically pristine. Admittedly, I don't have a full grasp of how the box model works with floats with overflowing content, so I don't understand why the combination of float: left on the container and the <pre> inside it cripple the max-width of the container. I'm observing the same problem on Firefox/Chrome/Safari/Opera. IE6 (the crazy one) seems happy all the time. This also doesn't seem dependent on quirks/standards mode. Update I've done further testing to observe that max-width seems to get ignored when the element has a float: left. I glanced at the W3C box model chapter but couldn't immediately see an explicit mention of this behaviour. Any pointers?

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• Log4r : logger inheritance, yaml configuration, alternatives ?

  - by devlearn

  Hello, I'm pretty new to ruby environments and I was looking for a nice logging framework to use it my ruby and rails applications. In my previous experiences I have successfully used log4j and log4p (the perl port) and was expecting the same level of usability (and maturity) with log4r. However I must say that there are a number of things that are not clear at all in the log4r framework. 1 Logger Inheritance The logger inheritance does not seem to be managed at all ! If I declare a logger named 'myapp' and then try to get a logger name 'myapp::engine', the lookup will end with a NameError. I would expect that the framework returns the root logger according to the naming scheme and to use the 'myapp' logger. Q1 : Of course I can work around this and manage the names by myself with a lookup method, however is there a cleaner way to do this without any extra coding ? 2 YAML configuration Second thing that confuses me is the yaml configuration. On the log4r site there are literally no information about this system, the doc links forward to missing pages, so all the info I can find about is contained in the examples directory of the gem. I was pretty confused with the fact that the yaml configuration must contain the pre_config section, and that I need to define my own levels. If I remove the pre_config secion, or replace all the “custom” levels by the standard ones ( debug, info, warn, fatal ) , the example will throw the following error : log4r/yamlconfigurator.rb:68:in `decode_yaml': Log level must be in 0..7 (ArgumentError) So there seems to be no way of using a simple file where we only declare the loggers and appenders for the framework. Q2 : I realy think that I missed something and that must be a way of providing a simple yaml conf file. Do you have any examples of such an usage ? 3 Variables substitution in XML file Q3 : The Yaml configuration system seems to provide such a feature however I was unable to find a similar feature with XML files. Any ideas ? 4 Alternatives ? I must say that I'm very disappointed by the feature level and the maturity of log4r compared to the log4j and other log4j ports. I run into this framework with a solid background of logging APIs in other languages and find myself working around in all kinds just to make 'basic things' running in a “real world application”. By that I mean a complex application composed of several gems, console/scripting apps, and a rails web front end where the configuration must be mutualized and where we make intensive usage of namespaces and inheritance. I've run several searches in order to find something more suitable or mature, but did not find anything similar. Q4 : Do you guys know any (serious) alternatives to log4r framework that could be used in a enterprise class app ? Thanks reading all of this ! I'd really appreciate any pointers, Kind Regards,

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• GWT & HTML5 Video in Mobile Safari

  - by KevMo

  I'm trying to code a site in GWT that plays videos with HTML5. Everything works great on the desktop, but mobile Safari on both the iPhone and iPad do not play the video. I can play a video using Video for Everybody. I've even copied the code to my own plain HTML page, and it works flawlessly. If I serve that same code via a GWT widget, mobile safari will not play the video. On the iPhone I see a gray box with a prohibitory sign around the play button, and on the iPad it shows up as a black box. I've made sure my doctype is <!DOCTYPE html>, but I don't know where else to start debugging. Perhaps it it because the code is injected via javascript? Any pointers on where to start looking would be greatly appreciated. Here is the exact code I am using for the video: <!-- "Video For Everybody" by Kroc Camen. see <camendesign.com/code/video_for_everybody> for documented code =================================================================================================================== --> <video width="640" height="360" poster="poster.jpg" controls autoplay> <source src="http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4" type="video/mp4"></source> <source src="http://clips.vorwaerts-gmbh.de/big_buck_bunny.ogv" type="video/ogg"></source> <!--[if gt IE 6]> <object width="640" height="375" classid="clsid:02BF25D5-8C17-4B23-BC80-D3488ABDDC6B"><! [endif]--><!--[if !IE]><!--> <object width="640" height="375" type="video/quicktime" data="http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4"> <!--<![endif]--> <param name="src" value="http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4" /> <param name="autoplay" value="true" /> <param name="showlogo" value="false" /> <object width="640" height="384" type="application/x-shockwave-flash" data="player.swf?autostart=true&amp;image=poster.jpg&amp;file=http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4"> <param name="movie" value="player.swf?autostart=true&amp;image=poster.jpg&amp;file=http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4" /> <!-- fallback image --> <img src="poster.jpg" width="640" height="360" alt="Big Buck Bunny" title="No video playback capabilities, please download the video below" /> </object><!--[if gt IE 6]><!--> </object><!--<![endif]--> </video>

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• Tactics for using PHP in a high-load site

  - by Ross

  Before you answer this I have never developed anything popular enough to attain high server loads. Treat me as (sigh) an alien that has just landed on the planet, albeit one that knows PHP and a few optimisation techniques. I'm developing a tool in PHP that could attain quite a lot of users, if it works out right. However while I'm fully capable of developing the program I'm pretty much clueless when it comes to making something that can deal with huge traffic. So here's a few questions on it (feel free to turn this question into a resource thread as well). Databases At the moment I plan to use the MySQLi features in PHP5. However how should I setup the databases in relation to users and content? Do I actually need multiple databases? At the moment everything's jumbled into one database - although I've been considering spreading user data to one, actual content to another and finally core site content (template masters etc.) to another. My reasoning behind this is that sending queries to different databases will ease up the load on them as one database = 3 load sources. Also would this still be effective if they were all on the same server? Caching I have a template system that is used to build the pages and swap out variables. Master templates are stored in the database and each time a template is called it's cached copy (a html document) is called. At the moment I have two types of variable in these templates - a static var and a dynamic var. Static vars are usually things like page names, the name of the site - things that don't change often; dynamic vars are things that change on each page load. My question on this: Say I have comments on different articles. Which is a better solution: store the simple comment template and render comments (from a DB call) each time the page is loaded or store a cached copy of the comments page as a html page - each time a comment is added/edited/deleted the page is recached. Finally Does anyone have any tips/pointers for running a high load site on PHP. I'm pretty sure it's a workable language to use - Facebook and Yahoo! give it great precedence - but are there any experiences I should watch out for? Thanks, Ross

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• How does mysql define DISTINCT() in reference documentation

  - by goran

  EDIT: This question is about finding definitive reference to MySQL syntax on SELECT modifying keywords and functions. /EDIT AFAIK SQL defines two uses of DISTINCT keywords - SELECT DISTINCT field... and SELECT COUNT(DISTINCT field) ... However in one of web applications that I administer I've noticed performance issues on queries like SELECT DISTINCT(field1), field2, field3 ... DISTINCT() on a single column makes no sense and I am almost sure it is interpreted as SELECT DISTINCT field1, field2, field3 ... but how can I prove this? I've searched mysql site for a reference on this particular syntax, but could not find any. Does anyone have a link to definition of DISTINCT() in mysql or knows about other authoritative source on this? Best EDIT After asking the same question on mysql forums I learned that while parsing the SQL mysql does not care about whitespace between functions and column names (but I am still missing a reference). As it seems you can have whitespace between functions and the parenthesis SELECT LEFT (field1,1), field2... and get mysql to understand it as SELECT LEFT(field,1) Similarly SELECT DISTINCT(field1), field2... seems to get decomposed to SELECT DISTINCT (field1), field2... and then DISTINCT is taken not as some undefined (or undocumented) function, but as SELECT modifying keyword and the parenthesis around field1 are evaluated as if they were part of field expression. It would be great if someone would have a pointer to documentation where it is stated that the whitespace between functions and parenthesis is not significant or to provide links to apropriate MySQL forums, mailing lists where I could raise a question to put this into reference. EDIT I have found a reference to server option IGNORE SPACE. It states that "The IGNORE SPACE SQL mode can be used to modify how the parser treats function names that are whitespace-sensitive", later on it states that recent versions of mysql have reduced this number from 200 to 30. One of the remaining 30 is COUNT for example. With IGNORE SPACE enabled both SELECT COUNT(*) FROM mytable; SELECT COUNT (*) FROM mytable; are legal. So if this is an exception, I am left to conclude that normally functions ignore space by default. If functions ignore space by default then if the context is ambiguous, such as for the first function on a first item of the select expression, then they are not distinguishable from keywords and the error can not be thrown and MySQL must accept them as keywords. Still, my conclusions feel like they have lot of assumptions, I would still be grateful and accept any pointers to see where to follow up on this.

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• iPhone Title and Subtitle in Navigation Bar

  - by Reuven

  Hi there, In my application, I'd like to have the navigation bar display a title and subtitle. To that extent, I added the following code to my view controller: // Replace titleView CGRect headerTitleSubtitleFrame = CGRectMake(0, 0, 200, 44); UIView* _headerTitleSubtitleView = [[[UILabel alloc] initWithFrame:headerTitleSubtitleFrame] autorelease]; _headerTitleSubtitleView.backgroundColor = [UIColor clearColor]; _headerTitleSubtitleView.autoresizesSubviews = YES; CGRect titleFrame = CGRectMake(0, 2, 200, 24); UILabel *titleView = [[[UILabel alloc] initWithFrame:titleFrame] autorelease]; titleView.backgroundColor = [UIColor clearColor]; titleView.font = [UIFont boldSystemFontOfSize:20]; titleView.textAlignment = UITextAlignmentCenter; titleView.textColor = [UIColor whiteColor]; titleView.shadowColor = [UIColor darkGrayColor]; titleView.shadowOffset = CGSizeMake(0, -1); titleView.text = @""; titleView.adjustsFontSizeToFitWidth = YES; [_headerTitleSubtitleView addSubview:titleView]; CGRect subtitleFrame = CGRectMake(0, 24, 200, 44-24); UILabel *subtitleView = [[[UILabel alloc] initWithFrame:subtitleFrame] autorelease]; subtitleView.backgroundColor = [UIColor clearColor]; subtitleView.font = [UIFont boldSystemFontOfSize:13]; subtitleView.textAlignment = UITextAlignmentCenter; subtitleView.textColor = [UIColor whiteColor]; subtitleView.shadowColor = [UIColor darkGrayColor]; subtitleView.shadowOffset = CGSizeMake(0, -1); subtitleView.text = @""; subtitleView.adjustsFontSizeToFitWidth = YES; [_headerTitleSubtitleView addSubview:subtitleView]; _headerTitleSubtitleView.autoresizingMask = (UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin); self.navigationItem.titleView = _headerTitleSubtitleView; And also implemented a method: -(void) setHeaderTitle:(NSString*)headerTitle andSubtitle:(NSString*)headerSubtitle { assert(self.navigationItem.titleView != nil); UIView* headerTitleSubtitleView = self.navigationItem.titleView; UILabel* titleView = [headerTitleSubtitleView.subviews objectAtIndex:0]; UILabel* subtitleView = [headerTitleSubtitleView.subviews objectAtIndex:1]; assert((titleView != nil) && (subtitleView != nil) && ([titleView isKindOfClass:[UILabel class]]) && ([subtitleView isKindOfClass:[UILabel class]])); titleView.text = headerTitle; subtitleView.text = headerSubtitle; } Things work beautifully, thanks. Except that when rotating the iPhone to Landscape, the title+subtitle don't downsize in an automatic manner like the default title of the navigation item. Any pointers? Thanks!

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• TVirtualStringTree - resetting non-visual nodes and memory consumption

  - by Remy Lebeau - TeamB

  I have an app that loads records from a binary log file and displays them in a virtual TListView. There are potentially millions of records in a file, and the display can be filtered by the user, so I do not load all of the records in memory at one time, and the ListView item indexes are not a 1-to-1 relation with the file record offsets (List item 1 may be file record 100, for instance). I use the ListView's OnDataHint event to load records for just the items the ListView is actually interested in. As the user scrolls around, the range specified by OnDataHint changes, allowing me to free records that are not in the new range, and allocate new records as needed. This works fine, speed is tolerable, and the memory footprint is very low. I am currently evaluating TVirtualStringTree as a replacement for the TListView, mainly because I want to add the ability to expand/collapse records that span multiple lines (I can fudge it with the TListView by incrementing/decrementing the item count dynamically, but this is not as straight forward as using a real tree). For the most part, I have been able to port the TListView logic and have everything work as I need. I notice that TVirtualStringTree's virtual paradigm is vastly different, though. It does not have the same kind of OnDataHint functionality that TListView does (I can use the OnScroll event to fake it, which allows my memory buffer logic to continue working), and I can use the OnInitializeNode event to associate nodes with records that are allocated. However, once a tree node is initialized, it sees that it remains initialized for the lifetime of the tree. That is not good for me. As the user scrolls around and I remove records from memory, I need to reset those non-visual nodes without removing them from the tree completely, or losing their expand/collapse states. When the user scrolls them back into view, I can re-allocate the records and re-initialize the nodes. Basically, I want to make TVirtualStringTree act as much like TListView as possible, as far as its virtualization is concerned. I have seen that TVirtualStringTree has a ResetNode() method, but I encounter various errors whenever I try to use it. I must be using it wrong. I also thought of just storing a data pointer inside each node to my record buffers, and I allocate and free memory, update those pointers accordingly. The end effect does not work so well, either. Worse, my largest test log file has ~5 million records in it. If I initialize the TVirtualStringTree with that many nodes at one time (when the log display is unfiltered), the tree's internal overhead for its nodes takes up a whopping 260MB of memory (without any records being allocated yet). Whereas with the TListView, loading the same log file and all the memory logic behind it, I can get away with using just a few MBs. Any ideas?

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• Animating custom-drawn UITableViewCell when entering edit mode

  - by Adam Alexander

  Background First of all, much gratitude to atebits for their very informative blog post Fast Scrolling in Tweetie with UITableView. The post explains in detail how the developers were able to squeeze as much scrolling performance as possible out of the UITableViews in Tweetie. Goals Beginning with the source code linked from the blog post (original) (my github repo): Allow a UITableView using these custom cells to switch to edit mode, exposing the UI for deleting an item from the table. (github commit) Move the cell's text aside as the deletion control slides in from the left. This is complete, although the text jumps back and forth without animation. (github commit) Apply animation to the text movement in goal 2 above for a smooth user experience. This is the step where I became stuck. The Question What is the best way to introduce this animation to complete goal 3? It would be nice if this could be done in a manner that keeps the logic from my last commit because I would love the option to move the conflicting part of the view only, while any non-conflicting portions (such as right-justified text) stay in the same place or move a different number of pixels. If the above is not possible then undoing my last commit and replacing it with an option that slides the entire view to the right would be a workable solution also. I appreciate any help anyone can provide, from quick pointers and ideas all the way to code snippets or github commits. Of course you are welcome to fork my repo if you would like. I will be staying involved with this question to make sure any successful resolution is committed to github and fully documented here. Thanks very much for your time! Updated thoughts I have been thinking about this a lot since my first post and realized that moving some text items relative to others in the view could undo some of the original performance goals solved in the original blog post. So at this point I am thinking a solution where the entire single subview is animated to its new postion may be the best one. Second, if it is done in this way there may be an instance where the subview has a custom color or gradient background. Hopefully this can be done in a way that in its normal position the background extends unseen off to the left enough so that when the view is slid to the right the custom background is still visible across the entire cell.

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• Retrieve EF4 POCOs using WCF REST services starter kit

  - by muruge

  I am using WCF REST service (GET method) to retrieve my EF4 POCOs. The service seem to work just fine. When I query the uri in my browser I get the results as expected. In my client application I am trying to use WCF REST Starter Kit's HTTPExtension method - ReadAsDataContract() to convert the result back into my POCO. This works fine when the POCO's navigation property is a single object of related POCO. The problem is when the navigation property is a collection of related POCOs. The ReadAsDataContract() method throws an exception with message "Object reference not set to an instance of an object." Below are my POCOs. [DataContract(Namespace = "", Name = "Trip")] public class Trip { [DataMember(Order = 1)] public virtual int TripID { get; set; } [DataMember(Order = 2)] public virtual int RegionID { get; set; } [DataMember(Order = 3)] public virtual System.DateTime BookingDate { get; set; } [DataMember(Order = 4)] public virtual Region Region { // removed for brevity } } [DataContract(Namespace = "", Name = "Region")] public class Region { [DataMember(Order = 1)] public virtual int RegionID { get; set; } [DataMember(Order = 2)] public virtual string RegionCode { get; set; } [DataMember(Order = 3)] public virtual FixupCollection<Trip> Trips { // removed for brevity } } [CollectionDataContract(Namespace = "", Name = "{0}s", ItemName = "{0}")] [Serializable] public class FixupCollection<T> : ObservableCollection<T> { protected override void ClearItems() { new List<T>(this).ForEach(t => Remove(t)); } protected override void InsertItem(int index, T item) { if (!this.Contains(item)) { base.InsertItem(index, item); } } } And this is how I am trying retrieve a Region POCO. static void GetRegion() { string uri = "http://localhost:8080/TripService/Regions?id=1"; HttpClient client = new HttpClient(uri); using (HttpResponseMessage response = client.Get(uri)) { Region region; response.EnsureStatusIsSuccessful(); try { region = response.Content.ReadAsDataContract<Region>(); // this line throws exception because Region returns a collection of related trips Console.WriteLine(region.RegionName); } catch (Exception ex) { Console.WriteLine(ex.Message); } } } Would appreciate any pointers.

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• Page expired issue with back button and wicket SortableDataProvider and DataTable

  - by David

  Hi, I've got an issue with SortableDataProvider and DataTable in wicket. I've defined my DataTable as such: IColumn<Column>[] columns = new IColumn[9]; //column values are mapped to the private attributes listed in ColumnImpl.java columns[0] = new PropertyColumn(new Model("#"), "columnPosition", "columnPosition"); columns[1] = new PropertyColumn(new Model("Description"), "description"); columns[2] = new PropertyColumn(new Model("Type"), "dataType", "dataType"); Adding it to the table: DataTable<Column> dataTable = new DataTable<Column>("columnsTable", columns, provider, maxRowsPerPage) { @Override protected Item<Column> newRowItem(String id, int index, IModel<Column> model) { return new OddEvenItem<Column>(id, index, model); } }; My data provider: public class ColumnSortableDataProvider extends SortableDataProvider<Column> { private static final long serialVersionUID = 1L; private List list = null; public ColumnSortableDataProvider(Table table, String sortProperty) { this.list = Arrays.asList(table.getColumns().toArray(new Column[0])); setSort(sortProperty, true); } public ColumnSortableDataProvider(List list, String sortProperty) { this.list = list; setSort(sortProperty, true); } @Override public Iterator iterator(int first, int count) { /* first - first row of data count - minimum number of elements to retrieve So this method returns an iterator capable of iterating over {first, first+count} items */ Iterator iterator = null; try { if(getSort() != null) { Collections.sort(list, new Comparator() { private static final long serialVersionUID = 1L; @Override public int compare(Column c1, Column c2) { int result=1; PropertyModel<Comparable> model1= new PropertyModel<Comparable>(c1, getSort().getProperty()); PropertyModel<Comparable> model2= new PropertyModel<Comparable>(c2, getSort().getProperty()); if(model1.getObject() == null && model2.getObject() == null) result = 0; else if(model1.getObject() == null) result = 1; else if(model2.getObject() == null) result = -1; else result = ((Comparable)model1.getObject()).compareTo(model2.getObject()); result = getSort().isAscending() ? result : -result; return result; } }); } if (list.size() (first+count)) iterator = list.subList(first, first+count).iterator(); else iterator = list.iterator(); } catch (Exception e) { e.printStackTrace(); } return iterator; } The problem is the following: - I click a column header to sort by that column. - I navigate to a different page - I click Back (or Forward if I do the opposite scenario) - Page has expired. It'd be nice to generate the page using PageParameters but I somehow need to intercept the sort event to do so. Any pointers would be greatly appreciated. Thanks a ton!! David

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• Mocking using boost::shared_ptr and AMOP

  - by Edison Gustavo Muenz

  Hi, I'm trying to write mocks using amop. I'm using Visual Studio 2008. I have this interface class: struct Interface { virtual void Activate() = 0; }; and this other class which receives pointers to this Interface, like this: struct UserOfInterface { void execute(Interface* iface) { iface->Activate(); } }; So I try to write some testing code like this: amop::TMockObject<Interface> mock; mock.Method(&Interface::Activate).Count(1); UserOfInterface user; user.execute((Interface*)mock); mock.Verifiy(); It works! So far so good, but what I really want is a boost::shared_ptr in the execute() method, so I write this: struct UserOfInterface { void execute(boost::shared_ptr<Interface> iface) { iface->Activate(); } }; How should the test code be now? I tried some things, like: amop::TMockObject<Interface> mock; mock.Method(&Interface::Activate).Count(1); UserOfInterface user; boost::shared_ptr<Interface> mockAsPtr((Interface*)mock); user.execute(mockAsPtr); mock.Verifiy(); It compiles, but obviously crashes, since at the end of the scope the variable 'mock' gets double destroyed (because of the stack variable 'mock' and the shared_ptr). I also tried to create the 'mock' variable on the heap: amop::TMockObject<Interface>* mock(new amop::TMockObject<Interface>); mock->Method(&Interface::Activate).Count(1); UserOfInterface user; boost::shared_ptr<Interface> mockAsPtr((Interface*)*mock); user.execute(mockAsPtr); mock->Verifiy(); But it doesn't work, somehow it enters an infinite loop, before I had a problem with boost not finding the destructor for the mocked object when the shared_ptr tried to delete the object. Has anyone used amop with boost::shared_ptr successfully?

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• Need help manipulating WAV (RIFF) Files at a byte level

  - by Eric

  I'm writing an an application in C# that will record audio files (*.wav) and automatically tag and name them. Wave files are RIFF files (like AVI) which can contain meta data chunks in addition to the waveform data chunks. So now I'm trying to figure out how to read and write the RIFF meta data to and from recorded wave files. I'm using NAudio for recording the files, and asked on their forums as well on SO for way to read and write RIFF tags. While I received a number of good answers, none of the solutions allowed for reading and writing RIFF chunks as easily as I would like. But more importantly I have very little experience dealing with files at a byte level, and think this could be a good opportunity to learn. So now I want to try writing my own class(es) that can read in a RIFF file and allow meta data to be read, and written from the file. I've used streams in C#, but always with the entire stream at once. So now I'm little lost that I have to consider a file byte by byte. Specifically how would I go about removing or inserting bytes to and from the middle of a file? I've tried reading a file through a FileStream into a byte array (byte[]) as shown in the code below. System.IO.FileStream waveFileStream = System.IO.File.OpenRead(@"C:\sound.wav"); byte[] waveBytes = new byte[waveFileStream.Length]; waveFileStream.Read(waveBytes, 0, waveBytes.Length); And I could see through the Visual Studio debugger that the first four byte are the RIFF header of the file. But arrays are a pain to deal with when performing actions that change their size like inserting or removing values. So I was thinking I could then to the byte[] into a List like this. List<byte> list = waveBytes.ToList<byte>(); Which would make any manipulation of the file byte by byte a whole lot easier, but I'm worried I might be missing something like a class in the System.IO name-space that would make all this even easier. Am I on the right track, or is there a better way to do this? I should also mention that I'm not hugely concerned with performance, and would prefer not to deal with pointers or unsafe code blocks like this guy. If it helps at all here is a good article on the RIFF/WAV file format.

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• Lucene.NET search index approach

  - by Tim Peel

  Hi, I am trying to put together a test case for using Lucene.NET on one of our websites. I'd like to do the following: Index in a single unique id. Index across a comma delimitered string of terms or tags. For example. Item 1: Id = 1 Tags = Something,Separated-Term I will then be structuring the search so I can look for documents against tag i.e. tags:something OR tags:separate-term I need to maintain the exact term value in order to search against it. I have something running, and the search query is being parsed as expected, but I am not seeing any results. Here's some code. My parser (_luceneAnalyzer is passed into my indexing service): var parser = new QueryParser(Lucene.Net.Util.Version.LUCENE_CURRENT, "Tags", _luceneAnalyzer); parser.SetDefaultOperator(QueryParser.Operator.AND); return parser; My Lucene.NET document creation: var doc = new Document(); var id = new Field( "Id", NumericUtils.IntToPrefixCoded(indexObject.id), Field.Store.YES, Field.Index.NOT_ANALYZED, Field.TermVector.NO); var tags = new Field( "Tags", string.Join(",", indexObject.Tags.ToArray()), Field.Store.NO, Field.Index.ANALYZED, Field.TermVector.YES); doc.Add(id); doc.Add(tags); return doc; My search: var parser = BuildQueryParser(); var query = parser.Parse(searchQuery); var searcher = Searcher; TopDocs hits = searcher.Search(query, null, max); IList<SearchResult> result = new List<SearchResult>(); float scoreNorm = 1.0f / hits.GetMaxScore(); for (int i = 0; i < hits.scoreDocs.Length; i++) { float score = hits.scoreDocs[i].score * scoreNorm; result.Add(CreateSearchResult(searcher.Doc(hits.scoreDocs[i].doc), score)); } return result; I have two documents in my index, one with the tag "Something" and one with the tags "Something" and "Separated-Term". It's important for the - to remain in the terms as I want an exact match on the full value. When I search with "tags:Something" I do not get any results. Question What Analyzer should I be using to achieve the search index I am after? Are there any pointers for putting together a search such as this? Why is my current search not returning any results? Many thanks

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• How to find minimum of nonlinear, multivariate function using Newton's method (code not linear algeb

  - by Norman Ramsey

  I'm trying to do some parameter estimation and want to choose parameter estimates that minimize the square error in a predicted equation over about 30 variables. If the equation were linear, I would just compute the 30 partial derivatives, set them all to zero, and use a linear-equation solver. But unfortunately the equation is nonlinear and so are its derivatives. If the equation were over a single variable, I would just use Newton's method (also known as Newton-Raphson). The Web is rich in examples and code to implement Newton's method for functions of a single variable. Given that I have about 30 variables, how can I program a numeric solution to this problem using Newton's method? I have the equation in closed form and can compute the first and second derivatives, but I don't know quite how to proceed from there. I have found a large number of treatments on the web, but they quickly get into heavy matrix notation. I've found something moderately helpful on Wikipedia, but I'm having trouble translating it into code. Where I'm worried about breaking down is in the matrix algebra and matrix inversions. I can invert a matrix with a linear-equation solver but I'm worried about getting the right rows and columns, avoiding transposition errors, and so on. To be quite concrete: I want to work with tables mapping variables to their values. I can write a function of such a table that returns the square error given such a table as argument. I can also create functions that return a partial derivative with respect to any given variable. I have a reasonable starting estimate for the values in the table, so I'm not worried about convergence. I'm not sure how to write the loop that uses an estimate (table of value for each variable), the function, and a table of partial-derivative functions to produce a new estimate. That last is what I'd like help with. Any direct help or pointers to good sources will be warmly appreciated. Edit: Since I have the first and second derivatives in closed form, I would like to take advantage of them and avoid more slowly converging methods like simplex searches.

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