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• Strategy for clients to retrieve real-time log from HTTP server

  - by Jerry Dodge

  I have an HTTP Server Service application which has its own logging mechanism. It's written in Delphi. I would like to provide a way for multiple clients to connect to this service and get a real-time update of the log. The log in the service moves rather fast, there's a lot of things to log. There may be up to 50 messages within 1 second at times. The existing log which is already implemented is not saved, it's only kept in the memory of the server service - where I will need to distribute it to any client which needs it. Once all clients have a log message, it should be deleted. I intend to use HTTP to "ask" the server for the log, and respond with an XML packet. The connections are not keep-alive. The only problem is, the server should only send the client those log records which it needs, not everything. I have no way of the server pushing the log to the clients in real-time, so each client needs to repeatedly ask the server for the latest log records. This HTTP Server is very lightweight, and there is no session management. There isn't even any type of authentication. The only way I see is for a client to register its self on the server, and whenever a log is issued on the server, it creates a copy of the log for each client, where each client has a log queue (string list). However, suppose there are 100 clients connected and expecting to receive this log. That means the server must create 100 copies of each log, add this log to the end of each client log queue, and wait for the client to request it. At that point, when the server replies with the XML log, it should flush (delete) whatever's in the queue. I'm worried however that this could cause memory issues. Each client log queue might get 100 log messages before the client requests the latest logs. How should I go about doing this in the fastest way possible without hindering the performance of the server? I'm trying to avoid having to create a copy of each log for each client.

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• Multithreading: Communication from Parent thread to child thread

  - by Dennis Nowland

  I have a List of threads normally 3 threads each of the threads reference a webbrowser control that communicates with the parent control to populate a datagridview. What I need to do is when the user clicks the button in a datagridviewButtonCell corresponding data will be sent back to the webbrowser control within the child thread that originally communicated with the main thread. but when I try to do this I receive the following error message 'COM object that has been separated from its underlying RCW cannot be used.' my problem is that I can not figure out how to reference the relevant webbrowser control. I would appreciate any help that anyone can give me. The language used is c# winforms .Net 4.0 targeted Code sample: The following code is executed when user click on the Start button in the main thread private void StartSubmit(object idx) { /* method used by the new thread to initialise a 'myBrowser' inherited from the webbrowser control each submitters object is an a custom Control called 'myBrowser' which holds detail about the function of the object eg: */ //index: is an integer value which represents the threads id int index = (int)idx; //submitters[index] is an instance of the 'myBrowser' control submitters[index] = new myBrowser(); //threads integer id submitters[index]._ThreadNum = index; // naming convention used 'browser' +the thread index submitters[index].Name = "browser" + index; //set list in 'myBrowser' class to hold a copy of the list found in the main thread submitters[index]._dirs = dirLists[index]; // suppress and javascript errors the may occur in the 'myBrowser' control submitters[index].ScriptErrorsSuppressed = true; //execute eventHandler submitters[index].DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(DocumentCompleted); //advance to the next un-opened address in datagridview the navigate the that address //in the 'myBrowser' control. SetNextDir(submitters[index]); } private void btnStart_Click(object sender, EventArgs e) { // used to fill list<string> for use in each thread. fillDirs(); //connections is the list<Thread> holding the thread that have been opened //1 to 10 maximum for (int n = 0; n < (connections.Length); n++) { //initialise new thread to the StartSubmit method passing parameters connections[n] = new Thread(new ParameterizedThreadStart(StartSubmit)); // naming convention used conn + the threadIndex ie: 'conn1' to 'conn10' connections[n].Name = "conn" + n.ToString(); // due to the webbrowser control needing to be ran in the single //apartment state connections[n].SetApartmentState(ApartmentState.STA); //start thread passing the threadIndex connections[n].Start(n); } } Once the 'myBrowser' control is fully loaded I am inserting form data into webforms found in webpages loaded via data enter into rows found in the datagridview. Once a user has entered the relevant details into the different areas in the row the can then clicking a DataGridViewButtonCell that has tha collects the data entered and then has to be send back to the corresponding 'myBrowser' object that is found on a child thread. Thank you

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• Recovering an Ubuntu installation - Ubuntu eats itself after 'sudo apt-get install -f'

  - by Tony Martin

  Updater (I assume) put a no entry style alert icon on the panel which informed me that certain package dependencies were not up to snuff. Upgrades were thereafter only partial. The dialogue advised that I sudo apt-get install -f. I did this hoping that app-get would fulfil dependencies and replace corrupted files and watched it systematically remove every component of linux, both the stuff I had installed and the core ubuntu packages. I could only assume at this stage that this was in preparation for a fresh install but, of course, I know better now - if you find yourself with apt-get warning you that you are about to remove several hundred packages and asking you to type an involved confirmation string seek advice before proceeding. I digress. This was a 64 bit install of 12.04. All that is left is grub pointing to a couple of windows recovery partitions on the hard drive. Thankfully the Ext4 partition is reachable from a stick boot. EDIT: I've logged onto the machine with a 64 bit stick and can see the file structure left behind by apt-get after {ahem} fixing. My first instinct was to run install from the stick but it seemed to want to do another install rather than a repair. My question then: is there a way to recover the current installation so that if I reinstall the packages I had they will pick up the original settings? I'm particularly worried about losing email from evolution - the rest I could probably lash back together. As for the use of PPA I'm not sure what you're driving at. I generally use Ubuntu Software Centre to install software, though I have used terminal scripts to add new repositories and software successfully following guidance on various websites. The most recent change I made was a downgrade of Wine in an attempt to install and run excel2007 (a necessity, I think, as I have VBA work to do). The installer had stalled and had to be killed. I wonder if that corrupted whatever database holds a model of the package installation structure. I would also be interested to know how this disaster came about. I see people in the know recommending the sudo apt-get install -f as a fairly innocuous cure in similar circumstances. Thanks for your attention, Tony Martin p.s. Do please forgive the rant aspects of the original post. It's hard to write rationally with a large hole in the pit of your stomach.

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• WebAPI and MVC4 and OData

  - by Aligned

  I was looking closer into WebAPI, specificially how to use OData to avoid writing GetCustomerByCustomerId(int id) methods all over the place. I had problems just returning IQueryable<T> as some sites suggested in the WebpAPI (Assembly System.Web.Http.dll, v4.0.0.0).  I think things changed in the release version and the blog posts are still out of date. There is no [Queraable] as the answer to this question suggests. Once I get WebAPI.Odata Nuget package, and added the [Queryable] to the method http://localhost:57146/api/values/?$filter=Id%20eq%201 worked (don’t forget the ‘$’). Now the main question is whether I should do this and how to stop logged in users from sniffing the url and getting data for other users. I John V. Peterson has a post on securing WebAPI with headers and intercepting the call at that point. He had an update to use HttpMessageHandlers instead. I think I’ll use this to force the call to contain some kind of unique code for the user, but I’m still thinking about this. I will not expose this to the public, just to my calls with-in my Forms Authentication areas. Other links: http://robbincremers.me/2012/02/16/building-and-consuming-rest-services-with-asp-net-web-api-and-odata-support/ ~lots of good information John V Peterson example: https://github.com/johnvpetersen/ASPWebAPIExample ~ all data access goes through the WebApi and the web client doesn’t have a connection string ~ There is code library for calling the WebApi from MVC using the HttpClient. It’s a great starting point http://blogs.msdn.com/b/alexj/archive/2012/08/15/odata-support-in-asp-net-web-api.aspx ~ Beta (9/18/2012) Nuget package to help with what I want to do? ~ has a sample code project with examples http://blogs.msdn.com/b/alexj/archive/2012/08/15/odata-support-in-asp-net-web-api.aspx http://blogs.msdn.com/b/alexj/archive/2012/08/21/web-api-queryable-current-support-and-tentative-roadmap.aspx http://stackoverflow.com/questions/10885868/asp-net-mvc4-rc-web-api-odata-filter-not-working-with-iqueryable JSON, pass the correct format in the header (Accept: application/json). $format=JSON doesn’t appear to be working. Async methods built into WebApi! Look for the GetAsync methods.

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• EJB Named Criteria - Apply bind variable in Backingbean

  - by Deepak Siddappa

  EJB Named criteria are predefined and reusable where-clause definitions that are dynamically applied to a ViewObject query. Here we often use to filter the ViewObject SQL statement query based on Where Clause conditions.Take a scenario where we need to filter the SQL statements query based on Where Clause conditions, instead of playing with SQL statements use the EJB Named Criteria which is supported by default in ADF and set the Bind Variable parameter at run time.You can download the sample workspace from here [Runs with Oracle JDeveloper 11.1.2.0.0 (11g R2) + HR Schema] Implementation StepsCreate Java EE Web Application with entity based on Employees table, then create a session bean and data control for the session bean.Open the DataControls.dcx file and create sparse xml for as shown below. In sparse xml navigate to Named criteria tab -> Bind Variable section, create binding variable deptId. Now create a named criteria and map the query attributes to the bind variable. In the ViewController create index.jspx page, from data control palette drop employeesFindAll->Named Criteria->EmployeesCriteria->Table as ADF Read-Only Filtered Table and create the backingBean as "IndexBean".Open the index.jspx page and remove the "filterModel" binding from the table, add <af:inputText />, command button and bind them to backingBean. For command button create the actionListener as "applyEmpCriteria" and add below code to the file. public void applyEmpCriteria(ActionEvent actionEvent) { DCIteratorBinding dc = (DCIteratorBinding)evaluteEL("#{bindings.employeesFindAllIterator}"); ViewObject vo = dc.getViewObject(); vo.applyViewCriteria(vo.getViewCriteriaManager().getViewCriteria("EmployeesCriteria")); vo.ensureVariableManager().setVariableValue("deptId", this.getDeptId().getValue()); vo.executeQuery(); } /** * Programmtic evaluation of EL * * @param el EL to evalaute * @return Result of the evalutaion */ public Object evaluteEL(String el) { FacesContext fctx = FacesContext.getCurrentInstance(); ELContext elContext = fctx.getELContext(); Application app = fctx.getApplication(); ExpressionFactory expFactory = app.getExpressionFactory(); ValueExpression valExp = expFactory.createValueExpression(elContext, el, Object.class); return valExp.getValue(elContext); } Run the index.jspx page, enter departmentId value as 90 and click in ApplyEmpCriteria button. Now the bind variable for the Named criteria will be applied at runtime in the backing bean and it will re-execute ViewObject query to filter based on where clause condition.

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• How to get better at solving Dynamic programming problems

  - by newbie

  I recently came across this question: "You are given a boolean expression consisting of a string of the symbols 'true', 'false', 'and', 'or', and 'xor'. Count the number of ways to parenthesize the expression such that it will evaluate to true. For example, there is only 1 way to parenthesize 'true and false xor true' such that it evaluates to true." I knew it is a dynamic programming problem so i tried to come up with a solution on my own which is as follows. Suppose we have a expression as A.B.C.....D where '.' represents any of the operations and, or, xor and the capital letters represent true or false. Lets say the number of ways for this expression of size K to produce a true is N. when a new boolean value E is added to this expression there are 2 ways to parenthesize this new expression 1. ((A.B.C.....D).E) ie. with all possible parenthesizations of A.B.C.....D we add E at the end. 2. (A.B.C.(D.E)) ie. evaluate D.E first and then find the number of ways this expression of size K can produce true. suppose T[K] is the number of ways the expression with size K produces true then T[k]=val1+val2+val3 where val1,val2,val3 are calculated as follows. 1)when E is grouped with D. i)It does not change the value of D ii)it inverses the value of D in the first case val1=T[K]=N.( As this reduces to the initial A.B.C....D expression ). In the second case re-evaluate dp[K] with value of D reversed and that is val1. 2)when E is grouped with the whole expression. //val2 contains the number of 'true' E will produce with expressions which gave 'true' among all parenthesized instances of A.B.C.......D i) if true.E = true then val2 = N ii) if true.E = false then val2 = 0 //val3 contains the number of 'true' E will produce with expressions which gave 'false' among all parenthesized instances of A.B.C.......D iii) if false.E=true then val3=( 2^(K-2) - N ) = M ie. number of ways the expression with size K produces a false [ 2^(K-2) is the number of ways to parenthesize an expression of size K ]. iv) if false.E=false then val3 = 0 This is the basic idea i had in mind but when i checked for its solution http://people.csail.mit.edu/bdean/6.046/dp/dp_9.swf the approach there was completely different. Can someone tell me what am I doing wrong and how can i get better at solving DP so that I can come up with solutions like the one given above myself. Thanks in advance.

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• Token based Authentication and Claims for Restful Services

  - by Your DisplayName here!

  WIF as it exists today is optimized for web applications (passive/WS-Federation) and SOAP based services (active/WS-Trust). While there is limited support for WCF WebServiceHost based services (for standard credential types like Windows and Basic), there is no ready to use plumbing for RESTful services that do authentication based on tokens. This is not an oversight from the WIF team, but the REST services security world is currently rapidly changing – and that’s by design. There are a number of intermediate solutions, emerging protocols and token types, as well as some already deprecated ones. So it didn’t make sense to bake that into the core feature set of WIF. But after all, the F in WIF stands for Foundation. So just like the WIF APIs integrate tokens and claims into other hosts, this is also (easily) possible with RESTful services. Here’s how. HTTP Services and Authentication Unlike SOAP services, in the REST world there is no (over) specified security framework like WS-Security. Instead standard HTTP means are used to transmit credentials and SSL is used to secure the transport and data in transit. For most cases the HTTP Authorize header is used to transmit the security token (this can be as simple as a username/password up to issued tokens of some sort). The Authorize header consists of the actual credential (consider this opaque from a transport perspective) as well as a scheme. The scheme is some string that gives the service a hint what type of credential was used (e.g. Basic for basic authentication credentials). HTTP also includes a way to advertise the right credential type back to the client, for this the WWW-Authenticate response header is used. So for token based authentication, the service would simply need to read the incoming Authorization header, extract the token, parse and validate it. After the token has been validated, you also typically want some sort of client identity representation based on the incoming token. This is regardless of how technology-wise the actual service was built. In ASP.NET (MVC) you could use an HttpModule or an ActionFilter. In (todays) WCF, you would use the ServiceAuthorizationManager infrastructure. The nice thing about using WCF’ native extensibility points is that you get self-hosting for free. This is where WIF comes into play. WIF has ready to use infrastructure built-in that just need to be plugged into the corresponding hosting environment: Representation of identity based on claims. This is a very natural way of translating a security token (and again I mean this in the widest sense – could be also a username/password) into something our applications can work with. Infrastructure to convert tokens into claims (called security token handler) Claims transformation Claims-based authorization So much for the theory. In the next post I will show you how to implement that for WCF – including full source code and samples. (Wanna learn more about federation, WIF, claims, tokens etc.? Click here.)

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• Obtaining positional information in the IEnumerable Select extension method

  - by Kyle Burns

  This blog entry is intended to provide a narrow and brief look into a way to use the Select extension method that I had until recently overlooked. Every developer who is using IEnumerable extension methods to work with data has been exposed to the Select extension method, because it is a pretty critical piece of almost every query over a collection of objects.  The method is defined on type IEnumerable and takes as its argument a function that accepts an item from the collection and returns an object which will be an item within the returned collection.  This allows you to perform transformations on the source collection.  A somewhat contrived example would be the following code that transforms a collection of strings into a collection of anonymous objects: 1: var media = new[] {"book", "cd", "tape"}; 2: var transformed = media.Select( item => 3: { 4: Media = item 5: } ); This code transforms the array of strings into a collection of objects which each have a string property called Media. If every developer using the LINQ extension methods already knows this, why am I blogging about it?  I’m blogging about it because the method has another overload that I hadn’t seen before I needed it a few weeks back and I thought I would share a little about it with whoever happens upon my blog.  In the other overload, the function defined in the first overload as: 1: Func<TSource, TResult> is instead defined as: 1: Func<TSource, int, TResult>   The additional parameter is an integer representing the current element’s position in the enumerable sequence.  I used this information in what I thought was a pretty cool way to compare collections and I’ll probably blog about that sometime in the near future, but for now we’ll continue with the contrived example I’ve already started to keep things simple and show how this works.  The following code sample shows how the positional information could be used in an alternating color scenario.  I’m using a foreach loop because IEnumerable doesn’t have a ForEach extension, but many libraries do add the ForEach extension to IEnumerable so you can update the code if you’re using one of these libraries or have created your own. 1: var media = new[] {"book", "cd", "tape"}; 2: foreach (var result in media.Select( 3: (item, index) => 4: new { Item = item, Index = index })) 5: { 6: Console.ForegroundColor = result.Index % 2 == 0 7: ? ConsoleColor.Blue : ConsoleColor.Yellow; 8: Console.WriteLine(result.Item); 9: }

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• glGetActiveAttrib on Android NDK

  - by user408952

  In my code-base I need to link the vertex declarations from a mesh to the attributes of a shader. To do this I retrieve all the attribute names after linking the shader. I use the following code (with some added debug info since it's not really working): int shaders[] = { m_ps, m_vs }; if(linkProgram(shaders, 2)) { ASSERT(glIsProgram(m_program) == GL_TRUE, "program is invalid"); int attrCount = 0; GL_CHECKED(glGetProgramiv(m_program, GL_ACTIVE_ATTRIBUTES, &attrCount)); int maxAttrLength = 0; GL_CHECKED(glGetProgramiv(m_program, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &maxAttrLength)); LOG_INFO("shader", "got %d attributes for '%s' (%d) (maxlen: %d)", attrCount, name, m_program, maxAttrLength); m_attrs.reserve(attrCount); GLsizei attrLength = -1; GLint attrSize = -1; GLenum attrType = 0; char tmp[256]; for(int i = 0; i < attrCount; i++) { tmp[0] = 0; GL_CHECKED(glGetActiveAttrib(m_program, GLuint(i), sizeof(tmp), &attrLength, &attrSize, &attrType, tmp)); LOG_INFO("shader", "%d: %d %d '%s'", i, attrLength, attrSize, tmp); m_attrs.append(String(tmp, attrLength)); } } GL_CHECKED is a macro that calls the function and calls glGetError() to see if something went wrong. This code works perfectly on Windows 7 using ANGLE and gives this this output: info:shader: got 2 attributes for 'static/simplecolor.glsl' (3) (maxlen: 11) info:shader: 0: 7 1 'a_Color' info:shader: 1: 10 1 'a_Position' But on my Nexus 7 (1st gen) I get the following (the errors are the output from the GL_CHECKED macro): I/testgame:shader(30865): got 2 attributes for 'static/simplecolor.glsl' (3) (maxlen: 11) E/testgame:gl(30865): 'glGetActiveAttrib(m_program, GLuint(i), sizeof(tmp), &attrLength, &attrSize, &attrType, tmp)' failed: INVALID_VALUE [jni/src/../../../../src/Game/Asset/ShaderAsset.cpp:50] I/testgame:shader(30865): 0: -1 -1 '' E/testgame:gl(30865): 'glGetActiveAttrib(m_program, GLuint(i), sizeof(tmp), &attrLength, &attrSize, &attrType, tmp)' failed: INVALID_VALUE [jni/src/../../../../src/Game/Asset/ShaderAsset.cpp:50] I/testgame:shader(30865): 1: -1 -1 '' I.e. the call to glGetActiveAttrib gives me an INVALID_VALUE. The opengl docs says this about the possible errors: GL_INVALID_VALUE is generated if program is not a value generated by OpenGL. This is not the case, I added an ASSERT to make sure glIsProgram(m_program) == GL_TRUE, and it doesn't trigger. GL_INVALID_OPERATION is generated if program is not a program object. Different error. GL_INVALID_VALUE is generated if index is greater than or equal to the number of active attribute variables in program. i is 0 and 1, and the number of active attribute variables are 2, so this isn't the case. GL_INVALID_VALUE is generated if bufSize is less than 0. Well, it's not zero, it's 256. Does anyone have an idea what's causing this? Am I just lucky that it works in ANGLE, or is the nvidia tegra driver wrong?

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• ApiChange Corporate Edition

  - by Alois Kraus

  In my inital announcement I could only cover a small subset what ApiChange can do for you. Lets look at how ApiChange can help you to fix bugs due to wrong usage of an Api within a fraction of time than it would take normally. It happens that software is tested and some bugs show up. One bug could be …. : We get way too man log messages during our test run. Now you have the task to find the most frequent messages and eliminate the Log calls from the source code. But what about the myriads other log calls? How can we check that the distribution of log calls is nearly equal across all developers? And if not how can we contact the developer to check his code? ApiChange can help you too connect these loose ends. It combines several information silos into one cohesive view. The picture below shows how it is able to fill the gaps. The public version does currently “only” parse the binaries and pdbs to give you for a –whousesmethod query the following colums: If it happens that you have Rational ClearCase (a source control system) in your development shop and an Active Directory in place then ApiChange will try to determine from the source file which was determined from the pdb the last check in user which should be present in your Active Directory. From there it is only a small hop to an LDAP query to your AD domain or the GC (Global Catalog) to get from the user name his Full name Email Phone number Department …. ApiChange will append this additional data all of your query results which contain source files if you add the –fileinfo option. As I said this is currently not enabled by default since the AD domain needs to be configured which are currently only some hard coded values in the SiteConstants.cs source file of ApiChange.Api.dll. Once you got this data you can generate metrics based on source file, developer, assembly, … and add additional data by drag and drop directly into the pivot tables inside Excel. This allows you to e.g. to generate a report which lists the source files with most log calls in descending order along with the developer name and email in the pivot table. Armed with this knowledge you can take meaningful measures e.g. to ask the developer if the huge number of log calls in this source file can be optimized. I am aware that this is a very specific scenario but it is a huge time saver when you are able to fill the missing gaps of information. ApiChange does this in an extensible way. namespace ApiChange.ExternalData {     public interface IFileInformationProvider     {         UserInfo GetInformationFromFile(string fileName);     } } It defines an interface where you can implement your custom information provider to close the gap between source control system and the real person I have to send an email to ask if his code needs a closer inspection.

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• Merge sort. ArrayIndexOutOfBoundsException [migrated]

  - by user94892

  When I execute the program I am getting an error as stated below the program. Please help me figure out the problem.. import java.util.*; class Mergesort { public static void main(String args[]) { Scanner in= new Scanner(System.in); System.out.println("Enter the number of elements"); int n= in.nextInt(); int a[]= new int[n]; System.out.println("Enter the contents"); for(int i=0; i<n; i++) { a[i]=in.nextInt(); } a = mergesort(a,n); for(int i=0; i<n; i++) { System.out.println(a[i]); } } public static int[] mergesort(int[] x, int z) { if(z==1) { return x; } int b[]=new int[z/2]; int c[]=new int[z-z/2]; int i,j,k; for(int p=0;p<z/2; p++) { b[p]= x[p]; c[p]= x[p+z/2]; } c[z-z/2-1]= x[z-1]; b= mergesort(b,z/2); c= mergesort(c,z-z/2); for(i=0,j=0,k=0; k<z; k++) { if(b[i]<=c[j]) { x[k]=b[i]; i++; } else if( b[i]>c[j]) { x[k]=c[j]; j++; } else if(i== z/2) { x[k]= c[j]; j++; } else if(j == z-z/2) { x[k]= b[i]; i++; } } return x; } } Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1 at Mergesort.mergesort(Mergesort.java:41) at Mergesort.mergesort(Mergesort.java:36) at Mergesort.main(Mergesort.java:16)

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• What is this algorithm for converting strings into numbers called?

  - by CodexArcanum

  I've been doing some work in Parsec recently, and for my toy language I wanted multi-based fractional numbers to be expressible. After digging around in Parsec's source a bit, I found their implementation of a floating-point number parser, and copied it to make the needed modifications. So I understand what this code does, and vaguely why (I haven't worked out the math fully yet, but I think I get the gist). But where did it come from? This seems like a pretty clever way to turn strings into floats and ints, is there a name for this algorithm? Or is it just something basic that's a hole in my knowledge? Did the folks behind Parsec devise it? Here's the code, first for integers: number' :: Integer -> Parser Integer number' base = do { digits <- many1 ( oneOf ( sigilRange base )) ; let n = foldl (\x d -> base * x + toInteger (convertDigit base d)) 0 digits ; seq n (return n) } So the basic idea here is that digits contains the string representing the whole number part, ie "192". The foldl converts each digit individually into a number, then adds that to the running total multiplied by the base, which means that by the end each digit has been multiplied by the correct factor (in aggregate) to position it. The fractional part is even more interesting: fraction' :: Integer -> Parser Double fraction' base = do { digits <- many1 ( oneOf ( sigilRange base )) ; let base' = fromIntegral base ; let f = foldr (\d x -> (x + fromIntegral (convertDigit base d))/base') 0.0 digits ; seq f (return f) Same general idea, but now a foldr and using repeated division. I don't quite understand why you add first and then divide for the fraction, but multiply first then add for the whole. I know it works, just haven't sorted out why. Anyway, I feel dumb not working it out myself, it's very simple and clever looking at it. Is there a name for this algorithm? Maybe the imperative version using a loop would be more familiar?

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• best way to "introduce" OOP/OOD to team of experienced C++ engineers

  - by DXM

  I am looking for an efficient way, that also doesn't come off as an insult, to introduce OOP concepts to existing team members? My teammates are not new to OO languages. We've been doing C++/C# for a long time so technology itself is familiar. However, I look around and without major infusion of effort (mostly in the form of code reviews), it seems what we are producing is C code that happens to be inside classes. There's almost no use of single responsibility principle, abstractions or attempts to minimize coupling, just to name a few. I've seen classes that don't have a constructor but get memset to 0 every time they are instantiated. But every time I bring up OOP, everyone always nods and makes it seem like they know exactly what I'm talking about. Knowing the concepts is good, but we (some more than others) seem to have very hard time applying them when it comes to delivering actual work. Code reviews have been very helpful but the problem with code reviews is that they only occur after the fact so to some it seems we end up rewriting (it's mostly refactoring, but still takes lots of time) code that was just written. Also code reviews only give feedback to an individual engineer, not the entire team. I am toying with the idea of doing a presentation (or a series) and try to bring up OOP again along with some examples of existing code that could've been written better and could be refactored. I could use some really old projects that no one owns anymore so at least that part shouldn't be a sensitive issue. However, will this work? As I said most people have done C++ for a long time so my guess is that a) they'll sit there thinking why I'm telling them stuff they already know or b) they might actually take it as an insult because I'm telling them they don't know how to do the job they've been doing for years if not decades. Is there another approach which would reach broader audience than a code review would, but at the same time wouldn't feel like a punishment lecture? I'm not a fresh kid out of college who has utopian ideals of perfectly designed code and I don't expect that from anyone. The reason I'm writing this is because I just did a review of a person who actually had decent high-level design on paper. However if you picture classes: A - B - C - D, in the code B, C and D all implement almost the same public interface and B/C have one liner functions so that top-most class A is doing absolutely all the work (down to memory management, string parsing, setup negotiations...) primarily in 4 mongo methods and, for all intents and purposes, calls almost directly into D. Update: I'm a tech lead(6 months in this role) and do have full support of the group manager. We are working on a very mature product and maintenance costs are definitely letting themselves be known.

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• Data Transformation Pipeline

  - by davenewza

  I have create some kind of data pipeline to transform coordinate data into more useful information. Here is the shell of pipeline: public class PositionPipeline { protected List<IPipelineComponent> components; public PositionPipeline() { components = new List<IPipelineComponent>(); } public PositionPipelineEntity Process(Position position) { foreach (var component in components) { position = component.Execute(position); } return position; } public PositionPipeline RegisterComponent(IPipelineComponent component) { components.Add(component); return this; } } Every IPipelineComponent accepts and returns the same type - a PositionPipelineEntity. Code: public interface IPipelineComponent { PositionPipelineEntity Execute(PositionPipelineEntity position); } The PositionPipelineEntity needs to have many properties, many which are unused in certain components and required in others. Some properties will also have become redundant at the end of the pipeline. For example, these components could be executed: TransformCoordinatesComponent: Parse the raw coordinate data into a Coordinate type. DetermineCountryComponent: Determine and stores country code. DetermineOnRoadComponent: Determine and store whether coordinate is on a road. Code: pipeline .RegisterComponent(new TransformCoordinatesComponent()) .RegisterComponent(new DetermineCountryComponent()) .RegisterComponent(new DetermineOnRoadComponent()); pipeline.Process(positionPipelineEntity); The PositionPipelineEntity type: public class PositionPipelineEntity { // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLatitude { get; set; } // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLongitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLatitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLongitude { get; set; } // Set in DetermineCountryComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public string CountryCode { get; set; } // Set in DetermineOnRoadComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public bool OnRoad { get; set; } } Problems: I'm very concerned about the dependency that a component has on properties. The way to solve this would be to create specific types for each component. The problem then is that I cannot chain them together like this. The other problem is the order of components in the pipeline matters. There is some dependency. The current structure does not provide any static or runtime checking for such a thing. Any feedback would be appreciated.

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• How to Remove Extensions From, and Force the Trailing Slash at the End of URLs?

  - by Kronbernkzion

  Example of current file structure: example.com/foo.php example.com/bar.html example.com/directory/ example.com/directory/foo.php example.com/directory/bar.html example.com/cgi-bin/directory/foo.cgi I would like to remove HTML, PHP and CGI extensions from, and then force the trailing slash at the end of URLs. So, it could look like this: example.com/foo/ example.com/bar/ example.com/directory/ example.com/directory/foo/ example.com/directory/bar/ example.com/cgi-bin/directory/foo/ I am very frustrated because I've searched for 17 hours straight for solution and visited more than a few hundred pages on various blogs and forums. I'm not joking. So I think I've done my research. Here is the code that sits in my .htaccess file right now: RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME}\.html -f RewriteRule ^(([^/]+/)*[^./]+)/$ $1.html RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]|/)$ RewriteRule (.*)$ /$1/ [R=301,L] As you can see, this code only removes .html (and I'm not very happy with it because I think it could be done a lot simpler). I can remove the extension from PHP files when I rename them to .html through .htaccess, but that's not what I want. I want to remove it straight. This is the first thing I don't know how to do. The second thing is actually very annoying. My .htaccess file with code above, adds .html/ to every string entered after example.com/directory/foo/. So if I enter example.com/directory/foo/bar (obviously /bar doesn't exist since foo is a file), instead of just displaying message that page is not found, it converts it to example.com/directory/foo/bar.html/, then searches for a file for a few seconds and then displays the not found message. This, of course, is bad behavior. So, once again, I need the code in .htaccess to do the following things: Remove .html extension Remove .php extension Remove .cgi extension Force the trailing slash at the end of URLs Requests should behave correctly (no adding trailing slashes or extensions to strings if file or directory doesn't exist on server) Code should be as simple as possible I would very much appreciate any help. And to first person that gives me the solution, I'll send two $50 iTunes Store gift cards for US store. If this offends anyone, I am truly sorry and I apologize. Thanks in advance.

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• Can see samba shares but not access them

  - by nitefrog

  For the life of me I cannot figure this one out. I have samba installed and set up on the ubuntu box and on the Win7 box I CAN SEE all the shares I created. I created two users on ubuntu that map to the users in windows. On ubuntu they are both admins, user A & B on Windows User A is admin and user B is poweruser. User A can see both shares and access them, but user B can see everythin, but only access the homes directory, the other directory throws an error. I have two drives in Ubuntu and this is the smb.config file (I am new to samba): [global] workgroup = WORKGROUP server string = %h server (Samba, Ubuntu) wins support = no dns proxy = yes name resolve order = lmhosts host wins bcast log file = /var/log/samba/log.%m max log size = 1000 syslog = 0 panic action = /usr/share/samba/panic-action %d security = user encrypt passwords = true passdb backend = tdbsam obey pam restrictions = yes unix password sync = yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . pam password change = yes map to guest = bad user ; usershare max shares = 100 usershare allow guests = yes And here is the share section: Both user A & B can access this from windows. No problems. [homes] comment = Home Directories browseable = no writable = yes Both User A & B can see this share, but only user A can access it. User B get an error thrown. [stuff] comment = Unixmen File Server path = /media/data/appinstall/ browseable = yes ;writable = no read only = yes hosts allow = The permission for the media/data/appinstall/ is as follows: appInstall properties: share name: stuff Allow others to create and delete files in this folder is cheeked Guest access (for people without a user account) is checked permissions: Owner: user A Folder Access: Create and delete files File Access: --- Group: user A Folder Access: Create and delete files File Access: --- Others Folder Access: Create and delete files File Access: --- I am at a loss and need to get this work. Any ideas? The goal is to have a setup like this. 3 users on window machines. Each user on the data drive will have their own personal folder where they are the ones that can only access, then another folder where 2 of the users will have read only and one user full access. I had this setup before on windows, but after what happened I am NEVER going back to windows, so Unix here I am to stay! I am really stuck. I am running Ubuntu 11. I could reformat again and put on version 10 if that would make life easier. I have been dealing with this since Wed. 3pm. Thanks.

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• With AMD style modules in JavaScript is there any benefit to namespaces?

  - by gman

  Coming from C++ originally and seeing lots of Java programmers doing the same we brought namespaces to JavaScript. See Google's closure library as an example where they have a main namespace, goog and under that many more namespaces like goog.async, goog.graphics But now, having learned the AMD style of requiring modules it seems like namespaces are kind of pointless in JavaScript. Not only pointless but even arguably an anti-pattern. What is AMD? It's a way of defining and including modules that removes all direct dependencies. Effectively you do this // some/module.js define([ 'name/of/needed/module', 'name/of/someother/needed/module', ], function( RefToNeededModule, RefToSomeOtherNeededModule) { ...code... return object or function }); This format lets the AMD support code know that this module needs name/of/needed/module.js and name/of/someother/needed/module.js loaded. The AMD code can load all the modules and then, assuming no circular dependencies, call the define function on each module in the correct order, record the object/function returned by the module as it calls them, and then call any other modules' define function with references to those modules. This seems to remove any need for namespaces. In your own code you can call the reference to any other module anything you want. For example if you had 2 string libraries, even if they define similar functions, as long as they follow the AMD pattern you can easily use both in the same module. No need for namespaces to solve that. It also means there's no hard coded dependencies. For example in Google's closure any module could directly reference another module with something like var value = goog.math.someMathFunc(otherValue) and if you're unlucky it will magically work where as with AMD style you'd have to explicitly include the math library otherwise the module wouldn't have a reference to it since there are no globals with AMD. On top of that dependency injection for testing becomes easy. None of the code in the AMD module references things by namespace so there is no hardcoded namespace paths, you can easily mock classes at testing time. Is there any other point to namespaces or is that something that C++ / Java programmers are bringing to JavaScript that arguably doesn't really belong?

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• Getting Started Plugging into the "Find in Projects" Dialog

  - by Geertjan

  In case you missed it amidst all the code in yesterday's blog entry, the "Find in Projects" dialog is now pluggable. I think that's really cool. The code yesterday gives you a complete example, but let's break it down a bit and deconstruct down to a very simple hello world scenario. We'll end up with as many extra tabs in the "Find in Projects" dialog as we need, for example, three in this case:  And clicking on any of those extra tabs will, in this simple example, simply show us this: Once we have that, we'll be able to continue adding small bits of code over the next few blog entries until we have something more useful. So, in this blog entry, you'll literally be able to display "Hello World" within a new tab in the "Find in Projects" dialog: import javax.swing.JComponent; import javax.swing.JLabel; import org.netbeans.spi.search.provider.SearchComposition; import org.netbeans.spi.search.provider.SearchProvider; import org.netbeans.spi.search.provider.SearchProvider.Presenter; import org.openide.NotificationLineSupport; import org.openide.util.lookup.ServiceProvider; @ServiceProvider(service = SearchProvider.class) public class ExampleSearchProvider1 extends SearchProvider { @Override public Presenter createPresenter(boolean replaceMode) { return new ExampleSearchPresenter(this); } @Override public boolean isReplaceSupported() { return false; } @Override public boolean isEnabled() { return true; } @Override public String getTitle() { return "Demo Extension 1"; } public class ExampleSearchPresenter extends SearchProvider.Presenter { private ExampleSearchPresenter(ExampleSearchProvider1 sp) { super(sp, true); } @Override public JComponent getForm() { return new JLabel("Hello World"); } @Override public SearchComposition composeSearch() { return null; } @Override public boolean isUsable(NotificationLineSupport nls) { return true; } } } That's it, not much code, works fine in NetBeans IDE 7.2 Beta, and is easier to digest than the big chunk from yesterday. If you make three classes like the above in a NetBeans module, and you install it, you'll have three new tabs in the "Find in Projects" dialog. The only required dependencies are Dialogs API, Lookup API, and Search in Projects API. Read the javadoc linked above and then in next blog entries we'll continue to build out something like the sample you saw in yesterday's blog entry.

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• cocos2d-x simple shader usage [on hold]

  - by Narek

  I want to obtain color ramp effect from this tutorial: http://www.raywenderlich.com/10862/how-to-create-cool-effects-with-custom-shaders-in-opengl-es-2-0-and-cocos2d-2-x Here is my code in cocos2d-x 3: bool HelloWorld::init() { ////////////////////////////// // 1. super init first if ( !Layer::init() ) { return false; } Vec2 origin = Director::getInstance()->getVisibleOrigin(); sprite = Sprite::create("HelloWorld.png"); sprite->setAnchorPoint(Vec2(0, 0)); sprite->setRotation(3); sprite->setPosition(origin); addChild(sprite); std::string str = FileUtils::getInstance()->getStringFromFile("CSEColorRamp.fsh"); const GLchar * fragmentSource = str.c_str(); GLProgram* p = GLProgram::createWithByteArrays(ccPositionTextureA8Color_vert, fragmentSource); p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_POSITION, GLProgram::VERTEX_ATTRIB_POSITION); p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_TEX_COORD, GLProgram::VERTEX_ATTRIB_TEX_COORD); p->link(); p->updateUniforms(); sprite->setGLProgram(p); // 3 colorRampUniformLocation = glGetUniformLocation(sprite->getGLProgram()->getProgram(), "u_colorRampTexture"); glUniform1i(colorRampUniformLocation, 1); // 4 colorRampTexture = Director::getInstance()->getTextureCache()->addImage("colorRamp.png"); colorRampTexture->setAliasTexParameters(); // 5 sprite->getGLProgram()->use(); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, colorRampTexture->getName()); glActiveTexture(GL_TEXTURE0); return true; } And here is the fragment shader as it is in the tutorial: #ifdef GL_ES precision mediump float; #endif // 1 varying vec2 v_texCoord; uniform sampler2D u_texture; uniform sampler2D u_colorRampTexture; void main() { // 2 vec3 normalColor = texture2D(u_texture, v_texCoord).rgb; // 3 float rampedR = texture2D(u_colorRampTexture, vec2(normalColor.r, 0)).r; float rampedG = texture2D(u_colorRampTexture, vec2(normalColor.g, 0)).g; float rampedB = texture2D(u_colorRampTexture, vec2(normalColor.b, 0)).b; // 4 gl_FragColor = vec4(rampedR, rampedG, rampedB, 1); } As a result I get a black screen with 2 draw calls. What is wrong? Do I miss something?

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• Playing with F#

  - by mroberts

  Project Euler is a awesome site.   When working with a new language it can be tricky to find problems that need solving, that are more complex than "Hello World" and simpler than a full blown application. Project Euler gives use just that, cool and thought provoking problems that usually don't take days to solve.  I've solved a number of questions with C# and some with Java.  BTW, I used Java because it had BigInteger support before .Net. A couple weeks ago, back when winter had a firm grip on Columbus, OH, I began playing (researching) with F#.  I began with Problem #1 from Project Euler.  I started by looking at my solution in C#. Here is my solution in C#. 1: using System; 2: using System.Collections.Generic; 3:   4: namespace Problem001 5: { 6: class Program 7: { 8: static void Main(string[] args) 9: { 10: List<int> values = new List<int>(); 11:   12: for (int i = 1; i < 1000; i++) 13: { 14: if (i % 3 == 0 || i % 5 == 0) 15: values.Add(i); 16: } 17: int total = 0; 18:   19: values.ForEach(v => total += v); 20:   21: Console.WriteLine(total); 22: Console.ReadKey(); 23: } 24: } 25: }   Now, after much tweaking and learning, here is my solution in F#.   1: open System 2:   3: let calc n = 4: [1..n] 5: |> List.map (fun x -> if (x % 3 = 0 || x % 5 = 0) then x else 0) 6: |> List.sum 7:   8: let main() = 9: calc 999 10: |> printfn "result = %d" 11: Console.ReadKey(true) |> ignore 12:   13: main() Just this little example highlights some cool things about F#. Type inference. F# infers the type of a value.  In the C# code above we declare a number of variables, the list, and a couple ints.  F# does not require this, it infers the calc (a function) accepts a int and returns a int. Great built in functionality for Lists.  List.map for example. BTW, I don’t think I’m spilling the beans by giving away the code for Problem 1.  It by far is the easiest question, IMHO, solved by 92,000+ people. Next I’ll look into writing a class library with F#.

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• How to keep a data structure synchronized over a network?

  - by David Gouveia

  Context In the game I'm working on (a sort of a point and click graphic adventure), pretty much everything that happens in the game world is controlled by an action manager that is structured a bit like: So for instance if the result of examining an object should make the character say hello, walk a bit and then sit down, I simply spawn the following code: var actionGroup = actionManager.CreateGroup(); actionGroup.Add(new TalkAction("Guybrush", "Hello there!"); actionGroup.Add(new WalkAction("Guybrush", new Vector2(300, 300)); actionGroup.Add(new SetAnimationAction("Guybrush", "Sit")); This creates a new action group (an entire line in the image above) and adds it to the manager. All of the groups are executed in parallel, but actions within each group are chained together so that the second one only starts after the first one finishes. When the last action in a group finishes, the group is destroyed. Problem Now I need to replicate this information across a network, so that in a multiplayer session, all players see the same thing. Serializing the individual actions is not the problem. But I'm an absolute beginner when it comes to networking and I have a few questions. I think for the sake of simplicity in this discussion we can abstract the action manager component to being simply: var actionManager = new List<List<string>>(); How should I proceed to keep the contents of the above data structure syncronized between all players? Besides the core question, I'm also having a few other concerns related to it (i.e. all possible implications of the same problem above): If I use a server/client architecture (with one of the players acting as both a server and a client), and one of the clients has spawned a group of actions, should he add them directly to the manager, or only send a request to the server, which in turn will order every client to add that group? What about packet losses and the like? The game is deterministic, but I'm thinking that any discrepancy in the sequence of actions executed in a client could lead to inconsistent states of the world. How do I safeguard against that sort of problem? What if I add too many actions at once, won't that cause problems for the connection? Any way to alleviate that?

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• Validate if aTextBox Value Start with a Specific Letter

  - by Vincent Maverick Durano

  In case you will be working on a page that needs to validate the first character of the TextBox entered by a user then here are two options that you can use: Option 1: Using an array   1: <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> 2: <script type="text/javascript"> 3: function CheckFirstChar(o) { 4: var arr = ['A', 'B', 'C', 'D']; 5: if (o.value.length > 0) { 6: for (var i = 0; i < arr.length; i++) { 7: if (o.value.charAt(0) == arr[i]) { 8: alert('Valid'); 9: return true; 10: } 11: else { 12: alert('InValid'); 13: return false; 14: } 15: } 16: } 17: } 18: </script> 19: </asp:Content> 20: <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> 21: <asp:TextBox ID="TextBox1" runat="server" onblur="return CheckFirstChar(this);"></asp:TextBox> 22: </asp:Content>   The example above uses an array of string for storing the list of  characters that a TextBox value should start with. We then iterate to the array and compare the first character of TextBox value to see if it matches any characters from the array. Option 2: Using Regular Expression (Preferred way)   1: <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> 2: <script type="text/javascript"> 3: function CheckFirstChar(o) { 4: pattern = /^(A|B|C|D)/; 5: if (!pattern.test(o.value)) { 6: alert('InValid'); 7: return false; 8: } else { 9: alert('Valid'); 10: return true; 11: } 12: } 13: </script> 14: </asp:Content> 15: <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> 16: <asp:TextBox ID="TextBox1" runat="server" onblur="return CheckFirstChar(this);"></asp:TextBox> 17: </asp:Content>   The example above uses regular expression with the pattern  /^(A|B|C|D)/. This will check if the TextBox value starts with A,B,C or D. Please note that it's case sensitive. If you want to allow lower case then you can alter the patter to this /^(A|B|C|D)/i. The i in the last part will cause a case-insensitive search.   That's it! I hope someone find this post useful!

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• OData &ndash; The easiest service I can create

  - by Jon Dalberg

  I wanted to create an OData service with the least amount of code so I fired up Visual Studio and got cracking. I decided to serve up a list of naughty words and make them read-only. Create a new web project. I created an empty MVC 2 application but MVC is not required for OData. Add a new WCF Data Service to the project. I named mine NastyWords.svc since I’m serving up a list of nasty words. Add a class to expose via the service: NastyWord 1: [DataServiceKey("Word")] 2: public class NastyWord 3: { 4: public string Word { get; set; } 5: }   I need to be able to uniquely identify instances of NastyWords for the DataService so I used the DataServiceKey attribute with the “Word” property as the key. I could have added an “ID” property which would have uniquely identified them and would then not need the “DataServiceKey” attribute because the DataService would apply some reflection and heuristics to guess at which property would be the unique identifier. However, the words themselves are unique so adding an “ID” property would be redundantly repetitive. Then I created a data source to expose my NastyWord objects to the service. This is just a simple class with IQueryable<T> properties exposing the entities for my service: 1: public class NastyWordsDataSource 2: { 3: private static IList<NastyWord> words = new List<NastyWord> 4: { 5: new NastyWord{ Word="crap"}, 6: new NastyWord{ Word="darn"}, 7: new NastyWord{ Word="hell"}, 8: new NastyWord{ Word="shucks"} 9: }; 10:   11: public NastyWordsDataSource() 12: { 13: NastyWords = words.AsQueryable(); 14: } 15:   16: public IQueryable<NastyWord> NastyWords { get; private set; } 17: }   Now I can go to the NastyWords.svc class and tell it which data source to use and which entities to expose: 1: public class NastyWords : DataService<NastyWordsDataSource> 2: { 3: // This method is called only once to initialize service-wide policies. 4: public static void InitializeService(DataServiceConfiguration config) 5: { 6: config.SetEntitySetAccessRule("*", EntitySetRights.AllRead); 7: config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; 8: } 9: }   Compile and browse to my NastWords.svc and weep with joy Now I can query my service just like any other OData service. Next time, I’ll modify this service to allow updates to sent so I can build up my list of nasty words. Enjoy!

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• Delay command execution over sockets

  - by David

  I've been trying to fix the game loop in a real time (tick delay) MUD. I realized using Thread.Sleep would seem clunky when the user spammed commands through their choice of client (Zmud, etc) e.g. east;south;southwest would wait three move ticks and then output everything from the past couple rooms. The game loop basically calls a Flush and Fill method for each socket during each tick (50ms) private void DoLoop() { Stopwatch stopWatch = new Stopwatch(); stopWatch.Start(); while (running) { // for each socket, flush and fill ConnectionMonitor.Update(); stopWatch.Stop(); WaitIfNeeded(stopWatch.ElapsedMilliseconds); stopWatch.Reset(); } } The Fill method fires the command events, but as mentioned before, they currently block using Thread.Sleep. I tried adding a "ready" flag to the state object that attempts to execute the command along with a queue of spammed commands, but it ends up executing one command and queuing up the rest i.e. each subsequent command executes something that got queued up that should've been executed before. I must be missing something about the timer. private readonly Queue<SpammedCommand> queuedCommands = new Queue<SpammedCommand>(); private bool ready = true; private void TryExecuteCommand(string input) { var commandContext = CommandContext.Create(input); var player = Server.Current.Database.Get<Player>(Session.Player.Key); var commandInfo = Server.Current.CommandLookup .FindCommand(commandContext.CommandName, player.IsAdmin); if (commandInfo != null) { if (!ready) { // queue command queuedCommands.Enqueue(new SpammedCommand() { Context = commandContext, Info = commandInfo }); return; } if (queuedCommands.Count > 0) { // queue the incoming command queuedCommands.Enqueue(new SpammedCommand() { Context = commandContext, Info = commandInfo, }); // dequeue and execute var command = queuedCommands.Dequeue(); command.Info.Command.Execute(Session, command.Context); setTimeout(command.Info.TickLength); return; } commandInfo.Command.Execute(Session, commandContext); setTimeout(commandInfo.TickLength); } else { Session.WriteLine("Command not recognized"); } } Finally, setTimeout was supposed to set the execution delay (TickLength) for that command, and makeReady just sets the ready flag on the state object to true. private void setTimeout(TickDelay tickDelay) { ready = false; var t = new System.Timers.Timer() { Interval = (long) tickDelay, AutoReset = false, }; t.Elapsed += makeReady; t.Start(); // fire this in tickDelay ms } // MAKE READYYYYY!!!! private void makeReady(object sender, System.Timers.ElapsedEventArgs e) { ready = true; } Am I missing something about the System.Timers.Timer created in setTimeout? How can I execute (and output) spammed commands per TickLength without using Thread.Sleep?

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• Understanding exceptional cases

  - by Justin

  I've been studying the use of exceptions in various php projects (such as Doctrine and Zend Framework). Exceptions seem to be thrown when unordinary input/state occurs. A perfect example is Doctrine throwing an exception when you try to use a invalid query string. I think the creators of the doctrine api understood that first, you can't query data by using an invalid DQL statement, and a developer should immediately be warned that an error has occurred, rather then letting execution continue with the possibility of an error code going un-checked. I also bet that this simplifies reading the code. I can't think of a situation where you would want to use an invalid DQL statement, except unit testing. Since this is true, it's better to avoid plaguing a bunch of code with null/error checks and use exceptions. I've read in books that exceptions shouldn't be thrown when validating dating user input. I've seen examples where of where the guideline is broken. One example is the Zend framework. If supplying an invalid controller or action name, an exception is thrown. Unlike doctrine, the user has more direct control over this sort of input. I know you can configure an error controller and set up a 404 message or what have you, but I'm curious why they have used an exception in this scenario? I guess you can argue the Zend Framework does not know how to continue processing the quest. One last example Is I wrote a function to return some html based on a given resource type. This resource type is hard-coded and sent when a user interacts with a web site (such as clicking a button to display the form to input data). I don't expect users to be mucking around with the request type. Under normal operating conditions, the resource type should be valid. To clean up some logic, I was going to throw an exception if a particular form wasn't found. This is mainly to find the correct form associated with a resource type so proper validation can occur. Does this sound like a valid use case for an exception? Right now it's pretty trivial, but I do plan to implement a restful consumer and re-using a function to map resources to their validation services would be very useful. I can then catch the exception and based on the consumer, return an error message suitable for the request type...

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