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  • How to understand such C macro expansion

    - by upton
    A macro definition: #define HTTP_ERRNO_MAP(XX) \ /* No error */ \ XX(OK, "success") \ \ /* Callback-related errors */ \ XX(CB_message_begin, "the on_message_begin callback failed") \ XX(CB_url, "the on_url callback failed") \ /* Define HPE_* values for each errno value above */ #define HTTP_ERRNO_GEN(n, s) HPE_##n, enum http_errno { HTTP_ERRNO_MAP(HTTP_ERRNO_GEN) }; #undef HTTP_ERRNO_GEN After expand it by "gcc -E", enum http_errno { HPE_OK, HPE_CB_message_begin, HPE_CB_url,}; How does the macro expand to the result?

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  • Python - How can I make this code asynchronous?

    - by dave
    Here's some code that illustrates my problem: def blocking1(): while True: yield 'first blocking function example' def blocking2(): while True: yield 'second blocking function example' for i in blocking1(): print 'this will be shown' for i in blocking2(): print 'this will not be shown' I have two functions which contain while True loops. These will yield data which I will then log somewhere (most likely, to an sqlite database). I've been playing around with threading and have gotten it working. However, I don't really like it... What I would like to do is make my blocking functions asynchronous. Something like: def blocking1(callback): while True: callback('first blocking function example') def blocking2(callback): while True: callback('second blocking function example') def log(data): print data blocking1(log) blocking2(log) How can I achieve this in Python? I've seen the standard library comes with asyncore and the big name in this game is Twisted but both of these seem to be used for socket IO. How can I async my non-socket related, blocking functions?

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  • Demystifying Silverlight Dependency Properties

    - by dwahlin
    I have the opportunity to teach a lot of people about Silverlight (amongst other technologies) and one of the topics that definitely confuses people initially is the concept of dependency properties. I confess that when I first heard about them my initial thought was “Why do we need a specialized type of property?” While you can certainly use standard CLR properties in Silverlight applications, Silverlight relies heavily on dependency properties for just about everything it does behind the scenes. In fact, dependency properties are an essential part of the data binding, template, style and animation functionality available in Silverlight. They simply back standard CLR properties. In this post I wanted to put together a (hopefully) simple explanation of dependency properties and why you should care about them if you’re currently working with Silverlight or looking to move to it.   What are Dependency Properties? XAML provides a great way to define layout controls, user input controls, shapes, colors and data binding expressions in a declarative manner. There’s a lot that goes on behind the scenes in order to make XAML work and an important part of that magic is the use of dependency properties. If you want to bind data to a property, style it, animate it or transform it in XAML then the property involved has to be a dependency property to work properly. If you’ve ever positioned a control in a Canvas using Canvas.Left or placed a control in a specific Grid row using Grid.Row then you’ve used an attached property which is a specialized type of dependency property. Dependency properties play a key role in XAML and the overall Silverlight framework. Any property that you bind, style, template, animate or transform must be a dependency property in Silverlight applications. You can programmatically bind values to controls and work with standard CLR properties, but if you want to use the built-in binding expressions available in XAML (one of my favorite features) or the Binding class available through code then dependency properties are a necessity. Dependency properties aren’t needed in every situation, but if you want to customize your application very much you’ll eventually end up needing them. For example, if you create a custom user control and want to expose a property that consumers can use to change the background color, you have to define it as a dependency property if you want bindings, styles and other features to be available for use. Now that the overall purpose of dependency properties has been discussed let’s take a look at how you can create them. Creating Dependency Properties When .NET first came out you had to write backing fields for each property that you defined as shown next: Brush _ScheduleBackground; public Brush ScheduleBackground { get { return _ScheduleBackground; } set { _ScheduleBackground = value; } } Although .NET 2.0 added auto-implemented properties (for example: public Brush ScheduleBackground { get; set; }) where the compiler would automatically generate the backing field used by get and set blocks, the concept is still the same as shown in the above code; a property acts as a wrapper around a field. Silverlight dependency properties replace the _ScheduleBackground field shown in the previous code and act as the backing store for a standard CLR property. The following code shows an example of defining a dependency property named ScheduleBackgroundProperty: public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), null);   Looking through the code the first thing that may stand out is that the definition for ScheduleBackgroundProperty is marked as static and readonly and that the property appears to be of type DependencyProperty. This is a standard pattern that you’ll use when working with dependency properties. You’ll also notice that the property explicitly adds the word “Property” to the name which is another standard you’ll see followed. In addition to defining the property, the code also makes a call to the static DependencyProperty.Register method and passes the name of the property to register (ScheduleBackground in this case) as a string. The type of the property, the type of the class that owns the property and a null value (more on the null value later) are also passed. In this example a class named Scheduler acts as the owner. The code handles registering the property as a dependency property with the call to Register(), but there’s a little more work that has to be done to allow a value to be assigned to and retrieved from the dependency property. The following code shows the complete code that you’ll typically use when creating a dependency property. You can find code snippets that greatly simplify the process of creating dependency properties out on the web. The MVVM Light download available from http://mvvmlight.codeplex.com comes with built-in dependency properties snippets as well. public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), null); public Brush ScheduleBackground { get { return (Brush)GetValue(ScheduleBackgroundProperty); } set { SetValue(ScheduleBackgroundProperty, value); } } The standard CLR property code shown above should look familiar since it simply wraps the dependency property. However, you’ll notice that the get and set blocks call GetValue and SetValue methods respectively to perform the appropriate operation on the dependency property. GetValue and SetValue are members of the DependencyObject class which is another key component of the Silverlight framework. Silverlight controls and classes (TextBox, UserControl, CompositeTransform, DataGrid, etc.) ultimately derive from DependencyObject in their inheritance hierarchy so that they can support dependency properties. Dependency properties defined in Silverlight controls and other classes tend to follow the pattern of registering the property by calling Register() and then wrapping the dependency property in a standard CLR property (as shown above). They have a standard property that wraps a registered dependency property and allows a value to be assigned and retrieved. If you need to expose a new property on a custom control that supports data binding expressions in XAML then you’ll follow this same pattern. Dependency properties are extremely useful once you understand why they’re needed and how they’re defined. Detecting Changes and Setting Defaults When working with dependency properties there will be times when you want to assign a default value or detect when a property changes so that you can keep the user interface in-sync with the property value. Silverlight’s DependencyProperty.Register() method provides a fourth parameter that accepts a PropertyMetadata object instance. PropertyMetadata can be used to hook a callback method to a dependency property. The callback method is called when the property value changes. PropertyMetadata can also be used to assign a default value to the dependency property. By assigning a value of null for the final parameter passed to Register() you’re telling the property that you don’t care about any changes and don’t have a default value to apply. Here are the different constructor overloads available on the PropertyMetadata class: PropertyMetadata Constructor Overload Description PropertyMetadata(Object) Used to assign a default value to a dependency property. PropertyMetadata(PropertyChangedCallback) Used to assign a property changed callback method. PropertyMetadata(Object, PropertyChangedCalback) Used to assign a default property value and a property changed callback.   There are many situations where you need to know when a dependency property changes or where you want to apply a default. Performing either task is easily accomplished by creating a new instance of the PropertyMetadata class and passing the appropriate values to its constructor. The following code shows an enhanced version of the initial dependency property code shown earlier that demonstrates these concepts: public Brush ScheduleBackground { get { return (Brush)GetValue(ScheduleBackgroundProperty); } set { SetValue(ScheduleBackgroundProperty, value); } } public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), new PropertyMetadata(new SolidColorBrush(Colors.LightGray), ScheduleBackgroundChanged)); private static void ScheduleBackgroundChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var scheduler = d as Scheduler; scheduler.Background = e.NewValue as Brush; } The code wires ScheduleBackgroundProperty to a property change callback method named ScheduleBackgroundChanged. What’s interesting is that this callback method is static (as is the dependency property) so it gets passed the instance of the object that owns the property that has changed (otherwise we wouldn’t be able to get to the object instance). In this example the dependency object is cast to a Scheduler object and its Background property is assigned to the new value of the dependency property. The code also handles assigning a default value of LightGray to the dependency property by creating a new instance of a SolidColorBrush. To Sum Up In this post you’ve seen the role of dependency properties and how they can be defined in code. They play a big role in XAML and the overall Silverlight framework. You can think of dependency properties as being replacements for fields that you’d normally use with standard CLR properties. In addition to a discussion on how dependency properties are created, you also saw how to use the PropertyMetadata class to define default dependency property values and hook a dependency property to a callback method. The most important thing to understand with dependency properties (especially if you’re new to Silverlight) is that they’re needed if you want a property to support data binding, animations, transformations and styles properly. Any time you create a property on a custom control or user control that has these types of requirements you’ll want to pick a dependency property over of a standard CLR property with a backing field. There’s more that can be covered with dependency properties including a related property called an attached property….more to come.

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  • Generating a twitter OAuth access key - the semi-manual way

    - by Piet
    [UPDATE] Apparently someone at Twitter was listening, or I’m going senile/blind. Let’s call it a combination of both. Instead of following all the steps below, you could just login with the Twitter account you want to use on http://dev.twitter.com, register your application and then click ‘Edit Details’ on the application overview page at http://dev.twitter.com/apps. Next click the ‘Application detail’ button on the right, followed by the ‘My Access Token’ button in order to get your Access Token and Access Token Secret. This makes the old post below rather obsolete. Clearly a case of me thinking everything is a nail and ruby is a hammer (don’t they usually say this about java coders?) [ORIGINAL POST] OAuth is great! OAuth allows your application to use your user’s data without the need to ask for their password. So Twitter made the API much safer for their and your users. Hurray! Free pizza for everyone! Unless of course you’re using the Twitter API for your own needs like running your own bot and don’t need access to other user’s data. In such cases a simple username/password combination is more than enough. I can understand however that the Twitter guys don’t really care that much about these exceptions(?). Most such uses for the API are probably rather spammy in nature. !!! If you have a twitter app that uses the API to access external user’s data: look for another solution. This solution is ONLY meant when you ONLY need access to your own account(s) through the API. Other Solutions Mr Dallas Devries posted a solution here which involves requesting and scraping a one-time PIN. But: I like to minimize the amount of calls I make to twitter’s API or pages to lessen my chances of meeting the fail whale. Also, as soon as the pin isn’t included in a div called ‘oauth_pin’ anymore, this will fail. However, mr Devries’ post was a starting point for my solution, so I’m much obliged to him posting his findings. Authenticating with the Twitter API: old vs new Acessing The Twitter API the old way: require ‘twitter’ httpauth = Twitter::HTTPAuth.new('my_account','my_secret_password') client = Twitter::Base.new(httpauth) client.update(‘Hurray!’) The OAuth way: require 'twitter' oauth = Twitter::OAuth.new('ve4whatafuzzksaMQKjoI', 'KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY') oauth.authorize_from_access('123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis', 'fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh') client = Twitter::Base.new(oauth) client.update(‘Hurray!’) In the above case, ve4whatafuzzksaMQKjoI is the ‘consumer key’ (sometimes also referred to as ‘consumer token’) and KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY is the ‘consumer secret’. You’ll get these from Twitter when you register your app. 123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis is the ‘access token’ and fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh is the ‘access secret’. This combination gives the registered application access to your account. I’ll show you how to obtain these by following the steps below. (Basically you’ll need a bunch of keys and you’ll have to jump a bit through hoops to obtain them for your server/bot. ) How to get these keys 1. Surf to the twitter apps registration page go to http://dev.twitter.com/apps to register your app. Login with your twitter account. 2. Register your application Enter something for Application name, Description, website,… as I said: they make you jump through hoops. If you plan on using the API to post tweets, Your application name and website will be used in the ‘5 minutes ago via…’ line below your tweet. You could use the this to point to a page with info about your bot, or maybe it’s useful for SEO purposes. For application type I choose ‘browser’ and entered http://www.hadermann.be/callback as a ‘Callback URL’. This url returns a 404 error, which is ideal because after giving our account access to our ‘application’ (step 6), it will redirect to this url with an ‘oauth_token’ and ‘oauth_verifier’ in the url. We need to get these from the url. It doesn’t really matter what you enter here though, you could leave it blank because you need to explicitely specify it when generating a request token. You probably want read&write access so set this at ‘Default Access type’. 3. Get your consumer key and consumer secret On the next page, copy/paste your ‘consumer key’ and ‘consumer secret’. You’ll need these later on. You also need these as part of the authentication in your script later on: oauth = Twitter::OAuth.new([consumer key], [consumer secret]) 4. Obtain your request token run the following in IRB to obtain your ‘request token’ Replace my fake consumer key and consumer secret with the one you obtained in step 3. And use something else instead http://www.hadermann.be/callback: although this will only give a 404, you shouldn’t trust me. irb(main):001:0> require 'oauth' irb(main):002:0> c = OAuth::Consumer.new('ve4whatafuzzksaMQKjoI', 'KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY', {:site => 'http://twitter.com'}) irb(main):003:0> request_token = c.get_request_token(:oauth_callback => 'http://www.hadermann.be/callback') irb(main):004:0> request_token.token => "UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1" This (UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1) is the request token: Copy/paste this token, you will need this next. 5. Authorize your application surf to https://api.twitter.com/oauth/authorize?oauth_token=[the above token], for example: https://api.twitter.com/oauth/authorize?oauth_token=UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1 This will bring you to the ‘An application would like to connect to your account’- screen on Twitter where you can grant access to the app you just registered. If you aren’t still logged in, you need to login first. Click ‘Allow’. Unless you don’t trust yourself. 6. Get your oauth_verifier from the redirected url Your browser will be redirected to your callback url, with an oauth_token and oauth_verifier parameter appended. You’ll need the oauth_verifier. In my case the browser redirected to: http://www.hadermann.be/callback?oauth_token=UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1&oauth_verifier=waoOhKo8orpaqvQe6rVi5fti4ejr8hPeZrTewyeag Which returned a 404, giving me the chance to copy/paste my oauth_verifier: waoOhKo8orpaqvQe6rVi5fti4ejr8hPeZrTewyeag 7. Request an access token Back to irb, use the oauth_verifier to request an access token, as follows: irb(main):005:0> at = request_token.get_access_token(:oauth_verifier => 'waoOhKo8orpaqvQe6rVi5fti4ejr8hPeZrTewyeag') irb(main):006:0> at.params[:oauth_token] => "123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis" irb(main):007:0> at.params[:oauth_token_secret] => "fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh" We’re there! 123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis is the access token. fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh is the access secret. Try it! Try the following to post an update: require 'twitter' oauth = Twitter::OAuth.new('ve4whatafuzzksaMQKjoI', 'KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY') oauth.authorize_from_access('123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis', 'fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh') client = Twitter::Base.new(oauth) client.update(‘Cowabunga!’) Now you can go to your twitter page and delete the tweet if you want to.

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  • How do I check user's unlocked achievement and leaderboard scores via GPG plugin

    - by noob
    I need to load user's achievement and their scores from leaderboard in my game. But the Social.LoadScore() and Social.LoadAchievements() both returns a 0 size array in callback. When I checked the implementation in Google Play Gaming's PlayGamePlatform.cs, both the method has this summary - Not implemented yet. Calls the callback with an empty list. So my question is How do I get this data in Unity? Has anyone tried any other method to get the data?

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  • Bullet Physics - Casting a ray straight down from a rigid body (first person camera)

    - by Hydrocity
    I've implemented a first person camera using Bullet--it's a rigid body with a capsule shape. I've only been using Bullet for a few days and physics engines are new to me. I use btRigidBody::setLinearVelocity() to move it and it collides perfectly with the world. The only problem is the Y-value moves freely, which I temporarily solved by setting the Y-value of the translation vector to zero before the body is moved. This works for all cases except when falling from a height. When the body drops off a tall object, you can still glide around since the translate vector's Y-value is being set to zero, until you stop moving and fall to the ground (the velocity is only set when moving). So to solve this I would like to try casting a ray down from the body to determine the Y-value of the world, and checking the difference between that value and the Y-value of the camera body, and disable or slow down movement if the difference is large enough. I'm a bit stuck on simply casting a ray and determining the Y-value of the world where it struck. I've implemented this callback: struct AllRayResultCallback : public btCollisionWorld::RayResultCallback{ AllRayResultCallback(const btVector3& rayFromWorld, const btVector3& rayToWorld) : m_rayFromWorld(rayFromWorld), m_rayToWorld(rayToWorld), m_closestHitFraction(1.0){} btVector3 m_rayFromWorld; btVector3 m_rayToWorld; btVector3 m_hitNormalWorld; btVector3 m_hitPointWorld; float m_closestHitFraction; virtual btScalar addSingleResult(btCollisionWorld::LocalRayResult& rayResult, bool normalInWorldSpace) { if(rayResult.m_hitFraction < m_closestHitFraction) m_closestHitFraction = rayResult.m_hitFraction; m_collisionObject = rayResult.m_collisionObject; if(normalInWorldSpace){ m_hitNormalWorld = rayResult.m_hitNormalLocal; } else{ m_hitNormalWorld = m_collisionObject->getWorldTransform().getBasis() * rayResult.m_hitNormalLocal; } m_hitPointWorld.setInterpolate3(m_rayFromWorld, m_rayToWorld, m_closestHitFraction); return 1.0f; } }; And in the movement function, I have this code: btVector3 from(pos.x, pos.y + 1000, pos.z); // pos is the camera's rigid body position btVector3 to(pos.x, 0, pos.z); // not sure if 0 is correct for Y AllRayResultCallback callback(from, to); Base::getSingletonPtr()->m_btWorld->rayTest(from, to, callback); So I have the callback.m_hitPointWorld vector, which seems to just show the position of the camera each frame. I've searched Google for examples of casting rays, as well as the Bullet documentation, and it's been hard to just find an example. An example is really all I need. Or perhaps there is some method in Bullet to keep the rigid body on the ground? I'm using Ogre3D as a rendering engine, and casting a ray down is quite straightforward with that, however I want to keep all the ray casting within Bullet for simplicity. Could anyone point me in the right direction? Thanks.

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  • What's the best way to start up a opengl context in my setup?

    - by NoobScratcher
    Would it be better to create a callback function which contains a OpenGL 3.0+ Context including viewport, matrix, etc or setup OpenGL in a function called GL_StartUp and use that GL_StartUp Function in the mainloop and callback function to that Function. I want my program to only show a OpenGL default scene when the user clicks on the New Game menu item in the menu bar rather then just have one setup when the program starts. I'm using Ubuntu 64bit, GTK 3.0 and GTK OpenGL

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  • Parallelism in .NET – Part 17, Think Continuations, not Callbacks

    - by Reed
    In traditional asynchronous programming, we’d often use a callback to handle notification of a background task’s completion.  The Task class in the Task Parallel Library introduces a cleaner alternative to the traditional callback: continuation tasks. Asynchronous programming methods typically required callback functions.  For example, MSDN’s Asynchronous Delegates Programming Sample shows a class that factorizes a number.  The original method in the example has the following signature: public static bool Factorize(int number, ref int primefactor1, ref int primefactor2) { //... .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, calling this is quite “tricky”, even if we modernize the sample to use lambda expressions via C# 3.0.  Normally, we could call this method like so: int primeFactor1 = 0; int primeFactor2 = 0; bool answer = Factorize(10298312, ref primeFactor1, ref primeFactor2); Console.WriteLine("{0}/{1} [Succeeded {2}]", primeFactor1, primeFactor2, answer); If we want to make this operation run in the background, and report to the console via a callback, things get tricker.  First, we need a delegate definition: public delegate bool AsyncFactorCaller( int number, ref int primefactor1, ref int primefactor2); Then we need to use BeginInvoke to run this method asynchronously: int primeFactor1 = 0; int primeFactor2 = 0; AsyncFactorCaller caller = new AsyncFactorCaller(Factorize); caller.BeginInvoke(10298312, ref primeFactor1, ref primeFactor2, result => { int factor1 = 0; int factor2 = 0; bool answer = caller.EndInvoke(ref factor1, ref factor2, result); Console.WriteLine("{0}/{1} [Succeeded {2}]", factor1, factor2, answer); }, null); This works, but is quite difficult to understand from a conceptual standpoint.  To combat this, the framework added the Event-based Asynchronous Pattern, but it isn’t much easier to understand or author. Using .NET 4’s new Task<T> class and a continuation, we can dramatically simplify the implementation of the above code, as well as make it much more understandable.  We do this via the Task.ContinueWith method.  This method will schedule a new Task upon completion of the original task, and provide the original Task (including its Result if it’s a Task<T>) as an argument.  Using Task, we can eliminate the delegate, and rewrite this code like so: var background = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); background.ContinueWith(task => Console.WriteLine("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result)); This is much simpler to understand, in my opinion.  Here, we’re explicitly asking to start a new task, then continue the task with a resulting task.  In our case, our method used ref parameters (this was from the MSDN Sample), so there is a little bit of extra boiler plate involved, but the code is at least easy to understand. That being said, this isn’t dramatically shorter when compared with our C# 3 port of the MSDN code above.  However, if we were to extend our requirements a bit, we can start to see more advantages to the Task based approach.  For example, supposed we need to report the results in a user interface control instead of reporting it to the Console.  This would be a common operation, but now, we have to think about marshaling our calls back to the user interface.  This is probably going to require calling Control.Invoke or Dispatcher.Invoke within our callback, forcing us to specify a delegate within the delegate.  The maintainability and ease of understanding drops.  However, just as a standard Task can be created with a TaskScheduler that uses the UI synchronization context, so too can we continue a task with a specific context.  There are Task.ContinueWith method overloads which allow you to provide a TaskScheduler.  This means you can schedule the continuation to run on the UI thread, by simply doing: Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }).ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), TaskScheduler.FromCurrentSynchronizationContext()); This is far more understandable than the alternative.  By using Task.ContinueWith in conjunction with TaskScheduler.FromCurrentSynchronizationContext(), we get a simple way to push any work onto a background thread, and update the user interface on the proper UI thread.  This technique works with Windows Presentation Foundation as well as Windows Forms, with no change in methodology.

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  • Anti-Forgery Request in ASP.NET MVC and AJAX

    - by Dixin
    Background To secure websites from cross-site request forgery (CSRF, or XSRF) attack, ASP.NET MVC provides an excellent mechanism: The server prints tokens to cookie and inside the form; When the form is submitted to server, token in cookie and token inside the form are sent by the HTTP request; Server validates the tokens. To print tokens to browser, just invoke HtmlHelper.AntiForgeryToken():<% using (Html.BeginForm()) { %> <%: this.Html.AntiForgeryToken(Constants.AntiForgeryTokenSalt)%> <%-- Other fields. --%> <input type="submit" value="Submit" /> <% } %> which writes to token to the form:<form action="..." method="post"> <input name="__RequestVerificationToken" type="hidden" value="J56khgCvbE3bVcsCSZkNVuH9Cclm9SSIT/ywruFsXEgmV8CL2eW5C/gGsQUf/YuP" /> <!-- Other fields. --> <input type="submit" value="Submit" /> </form> and the cookie: __RequestVerificationToken_Lw__=J56khgCvbE3bVcsCSZkNVuH9Cclm9SSIT/ywruFsXEgmV8CL2eW5C/gGsQUf/YuP When the above form is submitted, they are both sent to server. [ValidateAntiForgeryToken] attribute is used to specify the controllers or actions to validate them:[HttpPost] [ValidateAntiForgeryToken(Salt = Constants.AntiForgeryTokenSalt)] public ActionResult Action(/* ... */) { // ... } This is very productive for form scenarios. But recently, when resolving security vulnerabilities for Web products, I encountered 2 problems: It is expected to add [ValidateAntiForgeryToken] to each controller, but actually I have to add it for each POST actions, which is a little crazy; After anti-forgery validation is turned on for server side, AJAX POST requests will consistently fail. Specify validation on controller (not on each action) Problem For the first problem, usually a controller contains actions for both HTTP GET and HTTP POST requests, and usually validations are expected for HTTP POST requests. So, if the [ValidateAntiForgeryToken] is declared on the controller, the HTTP GET requests become always invalid:[ValidateAntiForgeryToken(Salt = Constants.AntiForgeryTokenSalt)] public class SomeController : Controller { [HttpGet] public ActionResult Index() // Index page cannot work at all. { // ... } [HttpPost] public ActionResult PostAction1(/* ... */) { // ... } [HttpPost] public ActionResult PostAction2(/* ... */) { // ... } // ... } If user sends a HTTP GET request from a link: http://Site/Some/Index, validation definitely fails, because no token is provided. So the result is, [ValidateAntiForgeryToken] attribute must be distributed to each HTTP POST action in the application:public class SomeController : Controller { [HttpGet] public ActionResult Index() // Works. { // ... } [HttpPost] [ValidateAntiForgeryToken(Salt = Constants.AntiForgeryTokenSalt)] public ActionResult PostAction1(/* ... */) { // ... } [HttpPost] [ValidateAntiForgeryToken(Salt = Constants.AntiForgeryTokenSalt)] public ActionResult PostAction2(/* ... */) { // ... } // ... } Solution To avoid a large number of [ValidateAntiForgeryToken] attributes (one attribute for one HTTP POST action), I created a wrapper class of ValidateAntiForgeryTokenAttribute, where HTTP verbs can be specified:[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)] public class ValidateAntiForgeryTokenWrapperAttribute : FilterAttribute, IAuthorizationFilter { private readonly ValidateAntiForgeryTokenAttribute _validator; private readonly AcceptVerbsAttribute _verbs; public ValidateAntiForgeryTokenWrapperAttribute(HttpVerbs verbs) : this(verbs, null) { } public ValidateAntiForgeryTokenWrapperAttribute(HttpVerbs verbs, string salt) { this._verbs = new AcceptVerbsAttribute(verbs); this._validator = new ValidateAntiForgeryTokenAttribute() { Salt = salt }; } public void OnAuthorization(AuthorizationContext filterContext) { string httpMethodOverride = filterContext.HttpContext.Request.GetHttpMethodOverride(); if (this._verbs.Verbs.Contains(httpMethodOverride, StringComparer.OrdinalIgnoreCase)) { this._validator.OnAuthorization(filterContext); } } } When this attribute is declared on controller, only HTTP requests with the specified verbs are validated:[ValidateAntiForgeryTokenWrapper(HttpVerbs.Post, Constants.AntiForgeryTokenSalt)] public class SomeController : Controller { // Actions for HTTP GET requests are not affected. // Only HTTP POST requests are validated. } Now one single attribute on controller turns on validation for all HTTP POST actions. Submit token via AJAX Problem For AJAX scenarios, when request is sent by JavaScript instead of form:$.post(url, { productName: "Tofu", categoryId: 1 // Token is not posted. }, callback); This kind of AJAX POST requests will always be invalid, because server side code cannot see the token in the posted data. Solution The token must be printed to browser then submitted back to server. So first of all, HtmlHelper.AntiForgeryToken() must be called in the page where the AJAX POST will be sent. Then jQuery must find the printed token in the page, and post it:$.post(url, { productName: "Tofu", categoryId: 1, __RequestVerificationToken: getToken() // Token is posted. }, callback); To be reusable, this can be encapsulated in a tiny jQuery plugin:(function ($) { $.getAntiForgeryToken = function () { // HtmlHelper.AntiForgeryToken() must be invoked to print the token. return $("input[type='hidden'][name='__RequestVerificationToken']").val(); }; var addToken = function (data) { // Converts data if not already a string. if (data && typeof data !== "string") { data = $.param(data); } data = data ? data + "&" : ""; return data + "__RequestVerificationToken=" + encodeURIComponent($.getAntiForgeryToken()); }; $.postAntiForgery = function (url, data, callback, type) { return $.post(url, addToken(data), callback, type); }; $.ajaxAntiForgery = function (settings) { settings.data = addToken(settings.data); return $.ajax(settings); }; })(jQuery); Then in the application just replace $.post() invocation with $.postAntiForgery(), and replace $.ajax() instead of $.ajaxAntiForgery():$.postAntiForgery(url, { productName: "Tofu", categoryId: 1 }, callback); // Token is posted. This solution looks hard coded and stupid. If you have more elegant solution, please do tell me.

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  • Drupal Ctools Form Wizard in a Block

    - by Iamjon
    Hi everyone I created a custom module that has a Ctools multi step form. It's basically a copy of http://www.nicklewis.org/using-chaos-tools-form-wizard-build-multistep-forms-drupal-6. The form works. I can see it if I got to the url i made for it. For the life of me I can't get the multistep form to show up in a block. Any clues? /** * Implementation of hook_block() * */ function mycrazymodule_block($op='list', $delta=0, $edit=array()) { switch ($op) { case 'list': $blocks[0]['info'] = t('SFT Getting Started'); $blocks[1]['info'] = t('SFT Contact US'); $blocks[2]['info'] = t('SFT News Letter'); return $blocks; case 'view': switch ($delta){ case '0': $block['subject'] = t('SFT Getting Started Subject'); $block['content'] = mycrazymodule_wizard(); break; case '1': $block['subject'] = t('SFT Contact US Subject'); $block['content'] = t('SFT Contact US content'); break; case '2': $block['subject'] = t('SFT News Letter Subject'); $block['content'] = t('SFT News Letter cONTENT'); break; } return $block; } } /** * Implementation of hook_menu(). */ function mycrazymodule_menu() { $items['hellocowboy'] = array( 'title' = 'Two Step Form', 'page callback' = 'mycrazymodule_wizard', 'access arguments' = array('access content') ); return $items; } /** * menu callback for the multistep form * step is whatever arg one is -- and will refer to the keys listed in * $form_info['order'], and $form_info['forms'] arrays */ function mycrazymodule_wizard() { $step = arg(1); // required includes for wizard $form_state = array(); ctools_include('wizard'); ctools_include('object-cache'); // The array that will hold the two forms and their options $form_info = array( 'id' = 'getting_started', 'path' = "hellocowboy/%step", 'show trail' = FALSE, 'show back' = FALSE, 'show cancel' = false, 'show return' =false, 'next text' = 'Submit', 'next callback' = 'getting_started_add_subtask_next', 'finish callback' = 'getting_started_add_subtask_finish', 'return callback' = 'getting_started_add_subtask_finish', 'order' = array( 'basic' = t('Step 1: Basic Info'), 'lecture' = t('Step 2: Choose Lecture'), ), 'forms' = array( 'basic' = array( 'form id' = 'basic_info_form' ), 'lecture' = array( 'form id' = 'choose_lecture_form' ), ), ); $form_state = array( 'cache name' = NULL, ); // no matter the step, you will load your values from the callback page $getstart = getting_started_get_page_cache(NULL); if (!$getstart) { // set form to first step -- we have no data $step = current(array_keys($form_info['order'])); $getstart = new stdClass(); //create cache ctools_object_cache_set('getting_started', $form_state['cache name'], $getstart); //print_r($getstart); } //THIS IS WHERE WILL STORE ALL FORM DATA $form_state['getting_started_obj'] = $getstart; // and this is the witchcraft that makes it work $output = ctools_wizard_multistep_form($form_info, $step, $form_state); return $output; } function basic_info_form(&$form, &$form_state){ $getstart = &$form_state['getting_started_obj']; $form['firstname'] = array( '#weight' = '0', '#type' = 'textfield', '#title' = t('firstname'), '#size' = 60, '#maxlength' = 255, '#required' = TRUE, ); $form['lastname'] = array( '#weight' = '1', '#type' = 'textfield', '#title' = t('lastname'), '#required' = TRUE, '#size' = 60, '#maxlength' = 255, ); $form['phone'] = array( '#weight' = '2', '#type' = 'textfield', '#title' = t('phone'), '#required' = TRUE, '#size' = 60, '#maxlength' = 255, ); $form['email'] = array( '#weight' = '3', '#type' = 'textfield', '#title' = t('email'), '#required' = TRUE, '#size' = 60, '#maxlength' = 255, ); $form['newsletter'] = array( '#weight' = '4', '#type' = 'checkbox', '#title' = t('I would like to receive the newsletter'), '#required' = TRUE, '#return_value' = 1, '#default_value' = 1, ); $form_state['no buttons'] = TRUE; } function basic_info_form_validate(&$form, &$form_state){ $email = $form_state['values']['email']; $phone = $form_state['values']['phone']; if(valid_email_address($email) != TRUE){ form_set_error('Dude you have an error', t('Where is your email?')); } //if (strlen($phone) 0 && !ereg('^[0-9]{1,3}-[0-9]{3}-[0-9]{3,4}-[0-9]{3,4}$', $phone)) { //form_set_error('Dude the phone', t('Phone number must be in format xxx-xxx-nnnn-nnnn.')); //} } function basic_info_form_submit(&$form, &$form_state){ //Grab the variables $firstname =check_plain ($form_state['values']['firstname']); $lastname = check_plain ($form_state['values']['lastname']); $email = check_plain ($form_state['values']['email']); $phone = check_plain ($form_state['values']['phone']); $newsletter = $form_state['values']['newsletter']; //Send the form and Grab the lead id $leadid = send_first_form($lastname, $firstname, $email,$phone, $newsletter); //Put into form $form_state['getting_started_obj']-firstname = $firstname; $form_state['getting_started_obj']-lastname = $lastname; $form_state['getting_started_obj']-email = $email; $form_state['getting_started_obj']-phone = $phone; $form_state['getting_started_obj']-newsletter = $newsletter; $form_state['getting_started_obj']-leadid = $leadid; } function choose_lecture_form(&$form, &$form_state){ $one = 'event 1' $two = 'event 2' $three = 'event 3' $getstart = &$form_state['getting_started_obj']; $form['lecture'] = array( '#weight' = '5', '#default_value' = 'two', '#options' = array( 'one' = $one, 'two' = $two, 'three' = $three, ), '#type' = 'radios', '#title' = t('Select Workshop'), '#required' = TRUE, ); $form['attendees'] = array( '#weight' = '6', '#default_value' = 'one', '#options' = array( 'one' = t('I will be arriving alone'), 'two' =t('I will be arriving with a guest'), ), '#type' = 'radios', '#title' = t('Attendees'), '#required' = TRUE, ); $form_state['no buttons'] = TRUE; } /** * Same idea as previous steps submit * */ function choose_lecture_form_submit(&$form, &$form_state) { $workshop = $form_state['values']['lecture']; $leadid = $form_state['getting_started_obj']-leadid; $attendees = $form_state['values']['attendees']; $form_state['getting_started_obj']-lecture = $workshop; $form_state['getting_started_obj']-attendees = $attendees; send_second_form($workshop, $attendees, $leadid); } /*----PART 3 CTOOLS CALLBACKS -- these usually don't have to be very unique ---------------------- */ /** * Callback generated when the add page process is finished. * this is where you'd normally save. */ function getting_started_add_subtask_finish(&$form_state) { dpm($form_state); $getstart = &$form_state['getting_started_obj']; drupal_set_message('mycrazymodule '.$getstart-name.' successfully deployed' ); //Get id // Clear the cache ctools_object_cache_clear('getting_started', $form_state['cache name']); $form_state['redirect'] = 'hellocowboy'; } /** * Callback for the proceed step * */ function getting_started_add_subtask_next(&$form_state) { dpm($form_state); $getstart = &$form_state['getting_started_obj']; $cache = ctools_object_cache_set('getting_started', $form_state['cache name'], $getstart); } /*----PART 4 CTOOLS FORM STORAGE HANDLERS -- these usually don't have to be very unique ---------------------- */ /** * Remove an item from the object cache. */ function getting_started_clear_page_cache($name) { ctools_object_cache_clear('getting_started', $name); } /** * Get the cached changes to a given task handler. */ function getting_started_get_page_cache($name) { $cache = ctools_object_cache_get('getting_started', $name); return $cache; } //Salesforce Functions function send_first_form($lastname, $firstname,$email,$phone, $newsletter){ $send = array("LastName" = $lastname , "FirstName" = $firstname, "Email" = $email ,"Phone" = $phone , "Newsletter__c" =$newsletter ); $sf = salesforce_api_connect(); $response = $sf-client-create(array($send), 'Lead'); dpm($response); return $response-id; } function send_second_form($workshop, $attendees, $leadid){ $send = array("Id" = $leadid , "Number_Of_Pepole__c" = "2" ); $sf = salesforce_api_connect(); $response = $sf-client-update(array($send), 'Lead'); dpm($response, 'the final response'); return $response-id; }

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  • Ajax call in a jQuery plugin not working properly

    - by Saneef
    I'm trying to create a jQuery plugin, inside I need to do an AJAX call to load an xml. jQuery.fn.imagetags = function(options) { s = jQuery.extend({ height:null, width:null, url:false, callback:null, title:null, }, options); return this.each(function(){ obj = $(this); //Initialising the placeholder $holder = $('<div />') .width(s.width).height(s.height) .addClass('jimageholder') .css({ position: 'relative', }); obj.wrap($holder); $.ajax({ type: "GET", url: s.url, dataType: "xml", success:function(data){ initGrids(obj,data,s.callback,s.title); } , error: function(data) { alert("Error loading Grid data."); }, }); function initGrids(obj, data,callback,gridtitle){ if (!data) { alert("Error loading Grid data"); } $("gridlist gridset",data).each(function(){ var gridsetname = $(this).children("setname").text(); var gridsetcolor = ""; if ($(this).children("color").text() != "") { gridsetcolor = $(this).children("color").text(); } $(this).children("grid").each(function(){ var gridcolor = gridsetcolor; //This colour will override colour set for the grid set if ($(this).children("color").text() != "") { gridcolor = $(this).children("color").text(); } //addGrid(gridsetname,id,x,y,height,width) addGrid( obj, gridsetname, $(this).children("id").text(), $(this).children("x").text(), $(this).children("y").text(), $(this).children("height").text(), $(this).children("width").text(), gridcolor, gridtitle ); }); }); } function addGrid(obj,gridsetname,id,x,y,height,width,color,gridtitle){ //To compensate for the 2px border height-=4; width-=4; $grid = $('<div />') .addClass(gridsetname) .attr("id",id) .addClass('gridtag') .imagetagsResetHighlight() .css({ "bottom":y+"px", "left":x+"px", "height":height+"px", "width":width+"px", }); if(gridtitle != null){ $grid.attr("title",gridtitle); } if(color != ""){ $grid.css({ "border-color":color, }); } obj.after($grid); } }); } The above plugin I bind with 2 DOM objects and loads two seperate XML files but the callback function is run only on the last DOM object using both loaded XML files. How can I fix this, so that the callback is applied on the corresponding DOMs. Is the above ajax call is correct? Sample usage: <script type="text/javascript"> $(function(){ $(".romeo img").imagetags({ height:500, width:497, url: "sample-data.xml", title: "Testing...", callback:function(id){ console.log(id); }, }); }); </script> <div class="padding-10 min-item background-color-black"> <div class="romeo"><img src="images/samplecontent/test_500x497.gif" alt="Image"> </div> </div> <script type="text/javascript"> $(function(){ $(".romeo2 img").imagetags({ height:500, width:497, url: "sample-data2.xml", title: "Testing...", callback:function(id){ console.log(id); }, }); }); </script> <div class="padding-10 min-item background-color-black"> <div class="romeo2"><img src="images/samplecontent/test2_500x497.gif" alt="Image"> </div> </div> Here is the sample XML data: <?xml version="1.0" encoding="utf-8"?> <gridlist> <gridset> <setname>gridset4</setname> <color>#00FF00</color> <grid> <color>#FF77FF</color> <id>grid2-324</id> <x>300</x> <y>300</y> <height>60</height> <width>60</width> </grid> </gridset> <gridset> <setname>gridset3</setname> <color>#00FF00</color> <grid> <color>#FF77FF</color> <id>grid2-212</id> <x>300</x> <y>300</y> <height>100</height> <width>100</width> </grid> <grid> <color>#FF77FF</color> <id>grid2-1212</id> <x>200</x> <y>10</y> <height>200</height> <width>10</width> </grid> </gridset> </gridlist>

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  • Darwin Streaming Server Interval Role

    - by Asmv9
    I want to use the Interval Role in Darwin streaming server,more specifically i want to call the QTSS_SetIntervalRoleTimer() when the server starts streaming a video file.But i have problem in doing this as from what it seems,the method returns QTSS_Err when i do that. I believe that the problem is due to the fact that the callback is made in a a module-created thread. Is there a specific place where this callback must be done?(if i put the callback in the register role of my module it works,but i dont want this,because i dont want the timer starting when the server starts).Any help will be useful,thank u in advance.

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  • How do I catch this WPF Bitmap loading exception?

    - by mmr
    I'm developing an application that loads bitmaps off of the web using .NET 3.5 sp1 and C#. The loading code looks like: try { CurrentImage = pics[unChosenPics[index]]; bi = new BitmapImage(CurrentImage.URI); // BitmapImage.UriSource must be in a BeginInit/EndInit block. bi.DownloadCompleted += new EventHandler(bi_DownloadCompleted); AssessmentImage.Source = bi; } catch { System.Console.WriteLine("Something broke during the read!"); } and the code to load on bi_DownloadCompleted is: void bi_DownloadCompleted(object sender, EventArgs e) { try { double dpi = 96; int width = bi.PixelWidth; int height = bi.PixelHeight; int stride = width * 4; // 4 bytes per pixel byte[] pixelData = new byte[stride * height]; bi.CopyPixels(pixelData, stride, 0); BitmapSource bmpSource = BitmapSource.Create(width, height, dpi, dpi, PixelFormats.Bgra32, null, pixelData, stride); AssessmentImage.Source = bmpSource; Loading.Visibility = Visibility.Hidden; AssessmentImage.Visibility = Visibility.Visible; } catch { System.Console.WriteLine("Exception when viewing bitmap."); } } Every so often, an image comes along that breaks the reader. I guess that's to be expected. However, rather than being caught by either of those try/catch blocks, the exception is apparently getting thrown outside of where I can handle it. I could handle it using global WPF exceptions, like this SO question. However, that will seriously mess up the control flow of my program, and I'd like to avoid that if at all possible. I have to do the double source assignment because it appears that many images are lacking in width/height parameters in the places where the microsoft bitmap loader expects them to be. So, the first assignment appears to force the download, and the second assignment gets the dpi/image dimensions happen properly. What can I do to catch and handle this exception? Stack trace: at MS.Internal.HRESULT.Check(Int32 hr) at System.Windows.Media.Imaging.BitmapFrameDecode.get_ColorContexts() at System.Windows.Media.Imaging.BitmapImage.FinalizeCreation() at System.Windows.Media.Imaging.BitmapImage.OnDownloadCompleted(Object sender, EventArgs e) at System.Windows.Media.UniqueEventHelper.InvokeEvents(Object sender, EventArgs args) at System.Windows.Media.Imaging.LateBoundBitmapDecoder.DownloadCallback(Object arg) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.TranslateAndDispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Application.RunInternal(Window window) at LensComparison.App.Main() in C:\Users\Mark64\Documents\Visual Studio 2008\Projects\LensComparison\LensComparison\obj\Release\App.g.cs:line 48 at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart()

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  • How to associate newly created SurfaceHolder to MediaPlayer

    - by fayerth
    In my code, I want to be able to temporarily hide (and subsequently show) a video. I am using a SurfaceView + MediaPlayer combination instead of the VideoView due to requirements. However, I am facing difficulties in getting video playback to occur as expected after I show the SurfaceView. My code excerpts includes the following: public void show() { if (mSurface != null) mSurface.setVisibility(View.VISIBLE); } public void hide() { if (mSurface != null) { if (isInPlaybackState()) pause(); mSurface.setVisibility(View.INVISIBLE); } } @Override public void surfaceCreated(final SurfaceHolder holder) { mHolder = holder; openVideo(); } @Override public void surfaceDestroyed(final SurfaceHolder holder) { // After this, the surface can't be used again mHolder = null; } private void openVideo() { if (mAssetPath == null || !mAssetPath.isEmpty() || mHolder == null) { // Not ready yet; try again later return; } // Pause music playback service Intent i = new Intent("com.android.music.musicservicecommand"); i.putExtra("command", "pause"); getActivity().sendBroadcast(i); if (mPlayer == null) { initializePlayer(); } else { mPlayer.setDisplay(mHolder); } } Based on the above, when I call hide(), surfaceDestroyed(SurfaceHolder) gets triggered. When I later call show(), surfaceCreated(SurfaceHolder) gets triggered, which will call openVideo() and associate the player with the newly provided SurfaceHolder. The above works as expected, and I believe this should be the correct process; however, when I call mPlayer.start(), I would hear the video's audio playing without any video and see the following error messages (which eventually causes the media playback to stop and complete, as noted by the disconnect logs): 10-23 11:29:42.775: E/MediaPlayer(4204): Error (1,-2147483648) 10-23 11:29:42.795: E/MediaPlayer(4204): Error (-38,0) 10-23 11:29:42.805: E/MediaPlayer(4204): Error (1,-2147483648) 10-23 11:29:42.810: V/MediaPlayer(4204): message received msg=100, ext1=1, ext2=-2147483648 10-23 11:29:42.810: E/MediaPlayer(4204): error (1, -2147483648) 10-23 11:29:42.810: V/MediaPlayer(4204): callback application 10-23 11:29:42.810: V/MediaPlayer(4204): back from callback 10-23 11:29:42.825: E/MediaPlayer(4204): Error (1,-2147483648) 10-23 11:29:42.850: V/MediaPlayer-JNI(4204): getCurrentPosition: 671668 (msec) 10-23 11:29:42.850: V/MediaPlayer-JNI(4204): getCurrentPosition: 671668 (msec) 10-23 11:29:42.850: V/MediaPlayer(4204): message received msg=100, ext1=1, ext2=-2147483648 10-23 11:29:42.850: E/MediaPlayer(4204): error (1, -2147483648) 10-23 11:29:42.850: V/MediaPlayer(4204): callback application 10-23 11:29:42.850: V/MediaPlayer(4204): back from callback 10-23 11:29:42.875: V/MediaPlayer-JNI(4204): stop 10-23 11:29:42.875: V/MediaPlayer(4204): stop 10-23 11:29:42.875: E/MediaPlayer(4204): stop called in state 0 10-23 11:29:42.875: V/MediaPlayer(4204): message received msg=100, ext1=-38, ext2=0 10-23 11:29:42.875: E/MediaPlayer(4204): error (-38, 0) 10-23 11:29:42.875: V/MediaPlayer(4204): callback application 10-23 11:29:42.875: V/MediaPlayer(4204): back from callback 10-23 11:29:42.875: V/MediaPlayer-JNI(4204): reset 10-23 11:29:42.875: V/MediaPlayer(4204): reset 10-23 11:29:42.900: V/MediaPlayer-JNI(4204): release 10-23 11:29:42.900: V/MediaPlayer(4204): setListener 10-23 11:29:42.900: V/MediaPlayer(4204): disconnect 10-23 11:29:42.910: V/MediaPlayer(4204): destructor 10-23 11:29:42.910: V/MediaPlayer(4204): disconnect Has anyone encountered this issue before and found a workaround? Or would the only option be to create a new MediaPlayer as well?

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  • Creating a JSONP Formatter for ASP.NET Web API

    - by Rick Strahl
    Out of the box ASP.NET WebAPI does not include a JSONP formatter, but it's actually very easy to create a custom formatter that implements this functionality. JSONP is one way to allow Browser based JavaScript client applications to bypass cross-site scripting limitations and serve data from the non-current Web server. AJAX in Web Applications uses the XmlHttp object which by default doesn't allow access to remote domains. There are number of ways around this limitation <script> tag loading and JSONP is one of the easiest and semi-official ways that you can do this. JSONP works by combining JSON data and wrapping it into a function call that is executed when the JSONP data is returned. If you use a tool like jQUery it's extremely easy to access JSONP content. Imagine that you have a URL like this: http://RemoteDomain/aspnetWebApi/albums which on an HTTP GET serves some data - in this case an array of record albums. This URL is always directly accessible from an AJAX request if the URL is on the same domain as the parent request. However, if that URL lives on a separate server it won't be easily accessible to an AJAX request. Now, if  the server can serve up JSONP this data can be accessed cross domain from a browser client. Using jQuery it's really easy to retrieve the same data with JSONP:function getAlbums() { $.getJSON("http://remotedomain/aspnetWebApi/albums?callback=?",null, function (albums) { alert(albums.length); }); } The resulting callback the same as if the call was to a local server when the data is returned. jQuery deserializes the data and feeds it into the method. Here the array is received and I simply echo back the number of items returned. From here your app is ready to use the data as needed. This all works fine - as long as the server can serve the data with JSONP. What does JSONP look like? JSONP is a pretty simple 'protocol'. All it does is wrap a JSON response with a JavaScript function call. The above result from the JSONP call looks like this:Query17103401925975181569_1333408916499( [{"Id":"34043957","AlbumName":"Dirty Deeds Done Dirt Cheap",…},{…}] ) The way JSONP works is that the client (jQuery in this case) sends of the request, receives the response and evals it. The eval basically executes the function and deserializes the JSON inside of the function. It's actually a little more complex for the framework that does this, but that's the gist of what happens. JSONP works by executing the code that gets returned from the JSONP call. JSONP and ASP.NET Web API As mentioned previously, JSONP support is not natively in the box with ASP.NET Web API. But it's pretty easy to create and plug-in a custom formatter that provides this functionality. The following code is based on Christian Weyers example but has been updated to the latest Web API CodePlex bits, which changes the implementation a bit due to the way dependent objects are exposed differently in the latest builds. Here's the code:  using System; using System.IO; using System.Net; using System.Net.Http.Formatting; using System.Net.Http.Headers; using System.Threading.Tasks; using System.Web; using System.Net.Http; namespace Westwind.Web.WebApi { /// <summary> /// Handles JsonP requests when requests are fired with /// text/javascript or application/json and contain /// a callback= (configurable) query string parameter /// /// Based on Christian Weyers implementation /// https://github.com/thinktecture/Thinktecture.Web.Http/blob/master/Thinktecture.Web.Http/Formatters/JsonpFormatter.cs /// </summary> public class JsonpFormatter : JsonMediaTypeFormatter { public JsonpFormatter() { SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json")); SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript")); //MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", "application/json")); JsonpParameterName = "callback"; } /// <summary> /// Name of the query string parameter to look for /// the jsonp function name /// </summary> public string JsonpParameterName {get; set; } /// <summary> /// Captured name of the Jsonp function that the JSON call /// is wrapped in. Set in GetPerRequestFormatter Instance /// </summary> private string JsonpCallbackFunction; public override bool CanWriteType(Type type) { return true; } /// <summary> /// Override this method to capture the Request object /// and look for the query string parameter and /// create a new instance of this formatter. /// /// This is the only place in a formatter where the /// Request object is available. /// </summary> /// <param name="type"></param> /// <param name="request"></param> /// <param name="mediaType"></param> /// <returns></returns> public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type, HttpRequestMessage request, MediaTypeHeaderValue mediaType) { var formatter = new JsonpFormatter() { JsonpCallbackFunction = GetJsonCallbackFunction(request) }; return formatter; } /// <summary> /// Override to wrap existing JSON result with the /// JSONP function call /// </summary> /// <param name="type"></param> /// <param name="value"></param> /// <param name="stream"></param> /// <param name="contentHeaders"></param> /// <param name="transportContext"></param> /// <returns></returns> public override Task WriteToStreamAsync(Type type, object value, Stream stream, HttpContentHeaders contentHeaders, TransportContext transportContext) { if (!string.IsNullOrEmpty(JsonpCallbackFunction)) { return Task.Factory.StartNew(() => { var writer = new StreamWriter(stream); writer.Write( JsonpCallbackFunction + "("); writer.Flush(); base.WriteToStreamAsync(type, value, stream, contentHeaders, transportContext).Wait(); writer.Write(")"); writer.Flush(); }); } else { return base.WriteToStreamAsync(type, value, stream, contentHeaders, transportContext); } } /// <summary> /// Retrieves the Jsonp Callback function /// from the query string /// </summary> /// <returns></returns> private string GetJsonCallbackFunction(HttpRequestMessage request) { if (request.Method != HttpMethod.Get) return null; var query = HttpUtility.ParseQueryString(request.RequestUri.Query); var queryVal = query[this.JsonpParameterName]; if (string.IsNullOrEmpty(queryVal)) return null; return queryVal; } } } Note again that this code will not work with the Beta bits of Web API - it works only with post beta bits from CodePlex and hopefully this will continue to work until RTM :-) This code is a bit different from Christians original code as the API has changed. The biggest change is that the Read/Write functions no longer receive a global context object that gives access to the Request and Response objects as the older bits did. Instead you now have to override the GetPerRequestFormatterInstance() method, which receives the Request as a parameter. You can capture the Request there, or use the request to pick up the values you need and store them on the formatter. Note that I also have to create a new instance of the formatter since I'm storing request specific state on the instance (information whether the callback= querystring is present) so I return a new instance of this formatter. Other than that the code should be straight forward: The code basically writes out the function pre- and post-amble and the defers to the base stream to retrieve the JSON to wrap the function call into. The code uses the Async APIs to write this data out (this will take some getting used to seeing all over the place for me). Hooking up the JsonpFormatter Once you've created a formatter, it has to be added to the request processing sequence by adding it to the formatter collection. Web API is configured via the static GlobalConfiguration object.  protected void Application_Start(object sender, EventArgs e) { // Verb Routing RouteTable.Routes.MapHttpRoute( name: "AlbumsVerbs", routeTemplate: "albums/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumApi" } ); GlobalConfiguration .Configuration .Formatters .Insert(0, new Westwind.Web.WebApi.JsonpFormatter()); }   That's all it takes. Note that I added the formatter at the top of the list of formatters, rather than adding it to the end which is required. The JSONP formatter needs to fire before any other JSON formatter since it relies on the JSON formatter to encode the actual JSON data. If you reverse the order the JSONP output never shows up. So, in general when adding new formatters also try to be aware of the order of the formatters as they are added. Resources JsonpFormatter Code on GitHub© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Error instantiating Texture2D in MonoGame for Windows 8 Metro Apps

    - by JimmyBoh
    I have an game which builds for WindowsGL and Windows8. The WindowsGL works fine, but the Windows8 build throws an error when trying to instantiate a new Texture2D. The Code: var texture = new Texture2D(CurrentGame.SpriteBatch.GraphicsDevice, width, 1); // Error thrown here... texture.setData(FunctionThatReturnsColors()); You can find the rest of the code on Github. The Error: SharpDX.SharpDXException was unhandled by user code HResult=-2147024809 Message=HRESULT: [0x80070057], Module: [Unknown], ApiCode: [Unknown/Unknown], Message: The parameter is incorrect. Source=SharpDX StackTrace: at SharpDX.Result.CheckError() at SharpDX.Direct3D11.Device.CreateTexture2D(Texture2DDescription& descRef, DataBox[] initialDataRef, Texture2D texture2DOut) at SharpDX.Direct3D11.Texture2D..ctor(Device device, Texture2DDescription description) at Microsoft.Xna.Framework.Graphics.Texture2D..ctor(GraphicsDevice graphicsDevice, Int32 width, Int32 height, Boolean mipmap, SurfaceFormat format, Boolean renderTarget) at Microsoft.Xna.Framework.Graphics.Texture2D..ctor(GraphicsDevice graphicsDevice, Int32 width, Int32 height) at BrewmasterEngine.Graphics.Content.Gradient.CreateHorizontal(Int32 width, Color left, Color right) in c:\Projects\Personal\GitHub\BrewmasterEngine\BrewmasterEngine\Graphics\Content\Gradient.cs:line 16 at SampleGame.Menu.Widgets.GradientBackground.UpdateBounds(Object sender, EventArgs args) in c:\Projects\Personal\GitHub\BrewmasterEngine\SampleGame\Menu\Widgets\GradientBackground.cs:line 39 at SampleGame.Menu.Widgets.GradientBackground..ctor(Color start, Color stop, Int32 scrollamount, Single scrollspeed, Boolean horizontal) in c:\Projects\Personal\GitHub\BrewmasterEngine\SampleGame\Menu\Widgets\GradientBackground.cs:line 25 at SampleGame.Scenes.IntroScene.Load(Action done) in c:\Projects\Personal\GitHub\BrewmasterEngine\SampleGame\Scenes\IntroScene.cs:line 23 at BrewmasterEngine.Scenes.Scene.LoadScene(Action`1 callback) in c:\Projects\Personal\GitHub\BrewmasterEngine\BrewmasterEngine\Scenes\Scene.cs:line 89 at BrewmasterEngine.Scenes.SceneManager.Load(String sceneName, Action`1 callback) in c:\Projects\Personal\GitHub\BrewmasterEngine\BrewmasterEngine\Scenes\SceneManager.cs:line 69 at BrewmasterEngine.Scenes.SceneManager.LoadDefaultScene(Action`1 callback) in c:\Projects\Personal\GitHub\BrewmasterEngine\BrewmasterEngine\Scenes\SceneManager.cs:line 83 at BrewmasterEngine.Framework.Game2D.LoadContent() in c:\Projects\Personal\GitHub\BrewmasterEngine\BrewmasterEngine\Framework\Game2D.cs:line 117 at Microsoft.Xna.Framework.Game.Initialize() at BrewmasterEngine.Framework.Game2D.Initialize() in c:\Projects\Personal\GitHub\BrewmasterEngine\BrewmasterEngine\Framework\Game2D.cs:line 105 at Microsoft.Xna.Framework.Game.DoInitialize() at Microsoft.Xna.Framework.Game.Run(GameRunBehavior runBehavior) at Microsoft.Xna.Framework.Game.Run() at Microsoft.Xna.Framework.MetroFrameworkView`1.Run() InnerException: Is this an error that needs to be solved in MonoGame, or is there something that I need to do differently in my engine and game?

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  • Object oriented wrapper around a dll

    - by Tom Davies
    So, I'm writing a C# managed wrapper around a native dll. The dll contains several hundred functions. In most cases, the first argument to each function is an opaque handle to a type internal to the dll. So, an obvious starting point for defining some classes in the wrapper would be to define classes corresponding to each of these opaque types, with each instance holding and managing the opaque handle (passed to its constructor) Things are a little awkward when dealing with callbacks from the dll. Naturally, the callback handlers in my wrapper have to be static, but the callbacks arguments invariable contain an opaque handle. In order to get from the static callback back to an object instance, I've created a static dictionary in each class, associating handles with class instances. In the constructor of each class, an entry is put into the dictionary, and this entry is then removed in the Destructors. When I receive a callback, I can then consult the dictionary to retrieve the class instance corresponding to the opaque reference. Are there any obvious flaws to this? Something that seems to be a problem is that the existence static dictionary means that the garbage collector will not act on my class instances that are otherwise unreachable. As they are never garbage collected, they never get removed from the dictionary, so the dictionary grows. It seems I might have to manually dispose of my objects, which is something absolutely would like to avoid. Can anyone suggest a good design that allows me to avoid having to do this?

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  • Testing a codebase with sequential cohesion

    - by iveqy
    I've this really simple program written in C with ncurses that's basically a front-end to sqlite3. I would like to implement TDD to continue the development and have found a nice C unit framework for this. However I'm totally stuck on how to implement it. Take this case for example: A user types a letter 'l' that is captured by ncurses getch(), and then an sqlite3 query is run that for every row calls a callback function. This callback function prints stuff to the screen via ncurses. So the obvious way to fully test this is to simulate a keyboard and a terminal and make sure that the output is the expected. However this sounds too complicated. I was thinking about adding an abstraction layer between the database and the UI so that the callback function will populate a list of entries and that list will later be printed. In that case I would be able to check if that list contains the expected values. However, why would I struggle with a data structure and lists in my program when sqlite3 already does this? For example, if the user wants to see the list sorted in some other way, it would be expensive to throw away the list and repopulate it. I would need to sort the list, but why should I implement sorting when sqlite3 already has that? Using my orginal design I could just do an other query sorted differently. Previously I've only done TDD with command line applications, and there it's really easy to just compare the output with what I'm expected. An other way would be to add CLI interface to the program and wrap a test program around the CLI to test everything. (The way git.git does with it's test-framework). So the question is, how to add testing to a tightly integrated database/UI.

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  • jquery ajax error cannot find url outside of debug mode

    - by John Orlandella Jr.
    I inherited some code two weeks ago that is using the jquery.ajax method to connect to a .NET web service. Here is the piece of code give me the trouble... if (MSCTour.AppSettings.OFFLINE !== 'TRUE') { $.ajax({ url: url, data: json, type: "POST", contentType: "application/json", timeout: 10000, dataType: "json", // not "json" we'll parse success: function(res){ if (!callback) { return; } /* // *** Use json library so we can fix up MS AJAX dates */ var result = ""; if (res !== "") { try { result = $.evalJSON(res); } catch (e) { result = {}; bare = true; } } /* // *** Bare message IS result */ if (bare) { callback(result); return; } /* // *** Wrapped message contains top level object node // *** strip it off */ for (var property in result) { callback(result[property]); break; } }, error: function(xhr,status,error){ if (status === 'parsererror') {} else {return error;} }, complete: function(res, status){ if (callback) { if ((status != 'success' && status != 'error') || status === 'parsererror' || (status === 'timeout' && res !== '')) { try { result = $.secureEvalJSON(res); } catch (e) { result = {}; bare = true; } callback(res); } } return; } }); } The url variable at this point equals /testsite/service.svc/GetItems Now here is where my problem lies... When running this site out of debug mode through visual studio I am not having any problem connecting to the database through the web service and seeing all my data, for both viewing and updating. When I go through the normal web server for the same site, on the same page, no data is showing up. When I put a break on the error portion of the code above in firebug this is information I am getting in the image linked below. link text I am getting what appears to be a 404 error, but when I look on the server all of the files are in the right place... coupled with the fact that it works when in debug mode, I think I am slowly going crazy staring at these same lines of code trying to find the needle in the haystack. Any help or just a direction to look in would be greatly appreciated.

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  • how to get $form_state outside of FAPI's functions?

    - by logii
    I'm writing a custom module and I'd like to use $form_state of the current form in another non-form api function - custom_facet_view_build(). any help is appreciated :) <?php /** * Implementation of hook_perm(). */ function custom_facet_perm() { return array( 'access foo content', 'access baz content', ); } /** * Implementation of hook_menu(). */ function custom_facet_menu() { $items['faceted-search'] = array( 'title' => 'Faceted Search', 'page callback' => 'drupal_get_form', 'access arguments' => array(), ); $items['facet-search-test'] = array( 'page callback' => 'drupal_get_form', 'page arguments' => array('custom_facet_form'), 'access callback' => TRUE, 'type' => MENU_CALLBACK, ); return $items; } /** * Form definition; ahah_helper_demo form. */ function custom_facet_form($form_state) { $form = array(); ahah_helper_register($form, $form_state); if (isset($form_state['storage']['categories'])) { $categories_default_value = $form_state['storage']['categories']["#value"]; } $form['facet_search_form'] = array( '#type' => 'fieldset', '#title' => t('Faceted Search'), '#prefix' => '<div id="billing-info-wrapper">', // This is our wrapper div. '#suffix' => '</div>', '#tree' => TRUE, // Don't forget to set #tree! ); $form['facet_search_form']['categories'] = array( '#type' => 'select', '#title' => t('Category'), '#options' => _custom_facet_taxonomy_query(1), '#multiple' => TRUE, '#default_value' => $categories_default_value, ); $form['save'] = array( '#type' => 'submit', '#value' => t('Save'), ); return $form; } /** * Validate callback for the form. */ function custom_facet_form_validate($form, &$form_state) { } /** * Submit callback for the form. */ function custom_facet_form_submit($form, &$form_state) { drupal_set_message('nothing done'); $form_state['storage']['categories'] = $form['facet_search_form']['categories']; // dpm($form_state); // There's a value returned in form_state['storage] within this function } /** * Implementation of hook_views_api(). */ function custom_facet_views_api() { return array( 'api' => 2, ); } function custom_facet_view_build(&$view) { dpm($form_state); // form_state['storage] remains NULL even though there's a value on previous submission }

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  • Handling WCF Service Paths in Silverlight 4 – Relative Path Support

    - by dwahlin
    If you’re building Silverlight applications that consume data then you’re probably making calls to Web Services. We’ve been successfully using WCF along with Silverlight for several client Line of Business (LOB) applications and passing a lot of data back and forth. Due to the pain involved with updating the ServiceReferences.ClientConfig file generated by a Silverlight service proxy (see Tim Heuer’s post on that subject to see different ways to deal with it) we’ve been using our own technique to figure out the service URL. Going that route makes it a peace of cake to switch between development, staging and production environments. To start, we have a ServiceProxyBase class that handles identifying the URL to use based on the XAP file’s location (this assumes that the service is in the same Web project that serves up the XAP file). The GetServiceUrlBase() method handles this work: public class ServiceProxyBase { public ServiceProxyBase() { if (!IsDesignTime) { ServiceUrlBase = GetServiceUrlBase(); } } public string ServiceUrlBase { get; set; } public static bool IsDesignTime { get { return (Application.Current == null) || (Application.Current.GetType() == typeof (Application)); } } public static string GetServiceUrlBase() { if (!IsDesignTime) { string url = Application.Current.Host.Source.OriginalString; return url.Substring(0, url.IndexOf("/ClientBin", StringComparison.InvariantCultureIgnoreCase)); } return null; } } Silverlight 4 now supports relative paths to services which greatly simplifies things.  We changed the code above to the following: public class ServiceProxyBase { private const string ServiceUrlPath = "../Services/JobPlanService.svc"; public ServiceProxyBase() { if (!IsDesignTime) { ServiceUrl = ServiceUrlPath; } } public string ServiceUrl { get; set; } public static bool IsDesignTime { get { return (Application.Current == null) || (Application.Current.GetType() == typeof (Application)); } } public static string GetServiceUrl() { if (!IsDesignTime) { return ServiceUrlPath; } return null; } } Our ServiceProxy class derives from ServiceProxyBase and handles creating the ABC’s (Address, Binding, Contract) needed for a WCF service call. Looking through the code (mainly the constructor) you’ll notice that the service URI is created by supplying the base path to the XAP file along with the relative path defined in ServiceProxyBase:   public class ServiceProxy : ServiceProxyBase, IServiceProxy { private const string CompletedEventargs = "CompletedEventArgs"; private const string Completed = "Completed"; private const string Async = "Async"; private readonly CustomBinding _Binding; private readonly EndpointAddress _EndPointAddress; private readonly Uri _ServiceUri; private readonly Type _ProxyType = typeof(JobPlanServiceClient); public ServiceProxy() { _ServiceUri = new Uri(Application.Current.Host.Source, ServiceUrl); var elements = new BindingElementCollection { new BinaryMessageEncodingBindingElement(), new HttpTransportBindingElement { MaxBufferSize = 2147483647, MaxReceivedMessageSize = 2147483647 } }; // order of entries in collection is significant: dumb _Binding = new CustomBinding(elements); _EndPointAddress = new EndpointAddress(_ServiceUri); } #region IServiceProxy Members /// <summary> /// Used to call a WCF service operation. /// </summary> /// <typeparam name="T">The type of EventArgs that will be returned by the service operation.</typeparam> /// <param name="callback">The method to call once the WCF call returns (the callback).</param> /// <param name="parameters">Any parameters that the service operation expects.</param> public void CallService<T>(EventHandler<T> callback, params object[] parameters) where T : EventArgs { try { var proxy = new JobPlanServiceClient(_Binding, _EndPointAddress); string action = typeof (T).Name.Replace(CompletedEventargs, String.Empty); _ProxyType.GetEvent(action + Completed).AddEventHandler(proxy, callback); _ProxyType.InvokeMember(action + Async, BindingFlags.InvokeMethod, null, proxy, parameters); } catch (Exception exp) { MessageBox.Show("Unable to use ServiceProxy.CallService to retrieve data: " + exp.Message); } } #endregion } The relative path support for calling services in Silverlight 4 definitely simplifies code and is yet another good reason to move from Silverlight 3 to Silverlight 4.   For more information about onsite, online and video training, mentoring and consulting solutions for .NET, SharePoint or Silverlight please visit http://www.thewahlingroup.com.

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  • Non-blocking I/O using Servlet 3.1: Scalable applications using Java EE 7 (TOTD #188)

    - by arungupta
    Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. In a typical application, ServletInputStream is read in a while loop. public class TestServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)         throws IOException, ServletException {     ServletInputStream input = request.getInputStream();       byte[] b = new byte[1024];       int len = -1;       while ((len = input.read(b)) != -1) {          . . .        }   }} If the incoming data is blocking or streamed slower than the server can read then the server thread is waiting for that data. The same can happen if the data is written to ServletOutputStream. This is resolved in Servet 3.1 (JSR 340, to be released as part Java EE 7) by adding event listeners - ReadListener and WriteListener interfaces. These are then registered using ServletInputStream.setReadListener and ServletOutputStream.setWriteListener. The listeners have callback methods that are invoked when the content is available to be read or can be written without blocking. The updated doGet in our case will look like: AsyncContext context = request.startAsync();ServletInputStream input = request.getInputStream();input.setReadListener(new MyReadListener(input, context)); Invoking setXXXListener methods indicate that non-blocking I/O is used instead of the traditional I/O. At most one ReadListener can be registered on ServletIntputStream and similarly at most one WriteListener can be registered on ServletOutputStream. ServletInputStream.isReady and ServletInputStream.isFinished are new methods to check the status of non-blocking I/O read. ServletOutputStream.canWrite is a new method to check if data can be written without blocking.  MyReadListener implementation looks like: @Overridepublic void onDataAvailable() { try { StringBuilder sb = new StringBuilder(); int len = -1; byte b[] = new byte[1024]; while (input.isReady() && (len = input.read(b)) != -1) { String data = new String(b, 0, len); System.out.println("--> " + data); } } catch (IOException ex) { Logger.getLogger(MyReadListener.class.getName()).log(Level.SEVERE, null, ex); }}@Overridepublic void onAllDataRead() { System.out.println("onAllDataRead"); context.complete();}@Overridepublic void onError(Throwable t) { t.printStackTrace(); context.complete();} This implementation has three callbacks: onDataAvailable callback method is called whenever data can be read without blocking onAllDataRead callback method is invoked data for the current request is completely read. onError callback is invoked if there is an error processing the request. Notice, context.complete() is called in onAllDataRead and onError to signal the completion of data read. For now, the first chunk of available data need to be read in the doGet or service method of the Servlet. Rest of the data can be read in a non-blocking way using ReadListener after that. This is going to get cleaned up where all data read can happen in ReadListener only. The sample explained above can be downloaded from here and works with GlassFish 4.0 build 64 and onwards. The slides and a complete re-run of What's new in Servlet 3.1: An Overview session at JavaOne is available here. Here are some more references for you: Java EE 7 Specification Status Servlet Specification Project JSR Expert Group Discussion Archive Servlet 3.1 Javadocs

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  • Dynamically load and call delegates based on source data

    - by makerofthings7
    Assume I have a stream of records that need to have some computation. Records will have a combination of these functions run Sum, Aggregate, Sum over the last 90 seconds, or ignore. A data record looks like this: Date;Data;ID Question Assuming that ID is an int of some kind, and that int corresponds to a matrix of some delegates to run, how should I use C# to dynamically build that launch map? I'm sure this idea exists... it is used in Windows Forms which has many delegates/events, most of which will never actually be invoked in a real application. The sample below includes a few delegates I want to run (sum, count, and print) but I don't know how to make the quantity of delegates fire based on the source data. (say print the evens, and sum the odds in this sample) using System; using System.Threading; using System.Collections.Generic; internal static class TestThreadpool { delegate int TestDelegate(int parameter); private static void Main() { try { // this approach works is void is returned. //ThreadPool.QueueUserWorkItem(new WaitCallback(PrintOut), "Hello"); int c = 0; int w = 0; ThreadPool.GetMaxThreads(out w, out c); bool rrr =ThreadPool.SetMinThreads(w, c); Console.WriteLine(rrr); // perhaps the above needs time to set up6 Thread.Sleep(1000); DateTime ttt = DateTime.UtcNow; TestDelegate d = new TestDelegate(PrintOut); List<IAsyncResult> arDict = new List<IAsyncResult>(); int count = 1000000; for (int i = 0; i < count; i++) { IAsyncResult ar = d.BeginInvoke(i, new AsyncCallback(Callback), d); arDict.Add(ar); } for (int i = 0; i < count; i++) { int result = d.EndInvoke(arDict[i]); } // Give the callback time to execute - otherwise the app // may terminate before it is called //Thread.Sleep(1000); var res = DateTime.UtcNow - ttt; Console.WriteLine("Main program done----- Total time --> " + res.TotalMilliseconds); } catch (Exception e) { Console.WriteLine(e); } Console.ReadKey(true); } static int PrintOut(int parameter) { // Console.WriteLine(Thread.CurrentThread.ManagedThreadId + " Delegate PRINTOUT waited and printed this:"+parameter); var tmp = parameter * parameter; return tmp; } static int Sum(int parameter) { Thread.Sleep(5000); // Pretend to do some math... maybe save a summary to disk on a separate thread return parameter; } static int Count(int parameter) { Thread.Sleep(5000); // Pretend to do some math... maybe save a summary to disk on a separate thread return parameter; } static void Callback(IAsyncResult ar) { TestDelegate d = (TestDelegate)ar.AsyncState; //Console.WriteLine("Callback is delayed and returned") ;//d.EndInvoke(ar)); } }

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