Download E-books TCP/IP Sockets in C#: Practical Guide for Programmers (The Practical Guides) PDF

Start and finish operations are meant to be symmetrical, and every name to a start process will be matched (at a few aspect) with an finish procedure name. Failure to take action in a long-running application creates an accumulation of nation upkeep for the uncompleted asynchronous calls . . . in different phrases, a reminiscence leak! Let’s examine a few concrete examples. The NetworkStream category comprises asynchronous models of its Write() and Read() tools, applied as BeginWrite(), EndWrite(), BeginRead(), and EndRead(). Let’s have a look at those equipment and think about how they relate to their blockading opposite numbers. The BeginRead() and BeginWrite() equipment take extra arguments and feature a unique go back kind: public override IAsyncResult BeginRead(byte[ ] buffer, int offset, int measurement, AsyncCallback callback, item state); public override IAsyncResult BeginWrite(byte[ ] buffer, int offset, int count number, AsyncCallback callback, item state); the 2 extra arguments are an example of AsyncCallback and an example of item, which are any C# category example (predefined or user-defined). The AsyncCallback type is a delegate that specifies the callback solution to invoke whilst the asynchronous alternative is whole. This category may be instantiated just by passing it the identify of the 118 bankruptcy four: past the fundamentals ■ technique for the callback: AsyncCallback ac = new AsyncCallback(myMethodToCall); :: : public static void myMethodToCall(IAsyncResult end result) { // callback code is going right here } If no callback procedure is needed, this argument might be null (although do not forget that the tip strategy needs to be invoked somewhere). The callback process itself should have the signature public static void (IAsyncResult). The IAsyncResult type might be mentioned in a second. the article argument is just the way to show user-defined info from the caller to the callback. this knowledge may be the NetworkStream or socket type example itself, or a user-defined type that incorporates either the NetworkStream, the byte buffer getting used, and the rest to which the appliance callback process wishes entry. The BeginRead() and BeginWrite() equipment actually have a assorted go back variety: an IAsyncResult example. The IAsyncResult represents the prestige of the asynchronous operation and will be used to ballot or block at the go back of that operation. when you choose to block watching for the operation to accomplish, the IAsyncResult’s AsyncWaitHandle estate encompasses a technique referred to as WaitOne(). Invoking this system will block until eventually the corresponding finish procedure is termed. as soon as the asynchronous operation completes, the callback approach is invoked. The callback procedure gets an IAsyncResult example as a controversy, which has a estate referred to as AsyncState that would comprise an item. This item is identical item that was once handed to the commence strategy, and wishes to be solid to its unique style earlier than getting used. The IAsyncResult example can be used because the argument to the tip name. the top name completes the symmetry of the decision and returns the results of the decision.