DEVELOPING CUSTOM SERVERS in VS .NET

Encoder Code 39 in VS .NET DEVELOPING CUSTOM SERVERS
DEVELOPING CUSTOM SERVERS
Code 39 Extended Recognizer In .NET Framework
Using Barcode Control SDK for Visual Studio .NET Control to generate, create, read, scan barcode image in .NET framework applications.
many other operations taking up bandwidth to slow things down. In reality this approach may work satisfactorily for small operations, but some operations will take longer and we will need to allow for this. For these we will want to work asynchronously. We can get an asynchronous stream simply by casting and then we associate event handlers with the stream. Handling writing of data is straightforward, so we will deal with it rst. The Write() method is similar to that for synchronous streams except that it does not return the number of bytes written. The OnWrite() event handler is invoked when the bytes have been fed across the connection (actually, it is not really possible to know when they have reached the other end because of buffering at various stages). You could ignore the OnWrite() event handler and just pump data in with the Write() method. The value of the OnWrite() event handler becomes apparent when you want to transfer a large amount of data in multiple buffers. Then you can Write() the rst bufferful and wait for the OnWrite() event before writing the next buffer. Other alternatives include just writing all of the buffers in turn with no delay (but the data will just get buffered up and you have a very real risk of either losing data or absorbing dangerous amounts of memory), or synchronously writing the data and waiting for a response message (which will work and is simple to program, but hogs the thread and makes it dif cult to handle cancelation or other interruptions). The asynchronous Write() method is the most ef cient solution. Having made the case for a sophisticated use of asynchronous Write() operations, we are writing only one buffer but in two stages (length rst and then data) in this example, so we will not really make use of the possibilities.
Code-39 Creator In Visual Studio .NET
Using Barcode encoder for VS .NET Control to generate, create Code 39 Full ASCII image in VS .NET applications.
void OnWrite( int aError ) { System.Console.WriteLine("OnWrite {0} error code", aError); } ... private SymbianConnectBAL.BALApplicationAsyncStream mAStream; ... // Now create an asynchronous stream from the synchronous one mAStream = (BALApplicationAsyncStream)myStream; mAStream.OnWrite += new ISCBALSequentialStreamSink_OnWriteEventHandler (OnWrite); System.Console.WriteLine("Enter text to be echoed"); string text=System.Console.ReadLine(); int textLen=text.Length; message = new byte[4]; WriteInt32(textLen, ref message, 0); // Write message length mAStream.Write(message);
USS Code 39 Reader In .NET Framework
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
ASYNCHRONOUS COMMUNICATION
Barcode Encoder In Visual Studio .NET
Using Barcode drawer for .NET framework Control to generate, create bar code image in .NET framework applications.
message = new byte[textLen]; for(int i = 0 ; i < textLen ; i++) {message[i] = (byte)text[i];} mAStream.Write(message);
Recognizing Bar Code In VS .NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
Having not really made use of the asynchronous possibilities when writing, we will try harder while reading. The actual API is straightforward, but effective use requires some planning. The Read() method returns immediately, but the data read (if any!) is not available until it appears in the event handler, so the handling of the data has to be included in the data handler. This means that we cannot have the simple sequential programming that we used with synchronous reads and writes, but this is part of the price we pay for the increased sophistication. This is also a pattern that is encountered in Symbian OS (in the custom servers, for example). As with the synchronous Read() method, we need to set how many bytes we want to read. If we were using xed-size buffers then we could set the whole read going in one operation, but it is more likely (and safer) that we will do it in two stages: we will read the length of the data rst and then the rest of the data based on that length. In this case we just print out the received data to the console, but later chapters will cover more interesting tasks.
Print Code 3/9 In C#.NET
Using Barcode printer for .NET framework Control to generate, create Code 39 Full ASCII image in .NET applications.
private bool mReadingLength; ... mAStream.OnRead += new ISCBALSequentialStreamSink_OnReadEventHandler (OnRead); ... // Try to read the length of data to come. // The actual data will be received by the OnRead event handler mReadingLength = true; mAStream.Read(4); ... public void OnRead( object aBuffer, int aError ) { System.Console.WriteLine("OnRead error {0} reading length {1}", aError, mReadingLength); byte[] buff = (byte[])aBuffer; System.Console.WriteLine("Buffer length {0}", buff.Length); if(mReadingLength && buff.Length >= 4) { // We have just read the length of the buffer int msgLen = ReadInt32(ref buff, 0); System.Console.WriteLine("Message length is {0}", msgLen); // Trigger the read of the rest of the buffer if(msgLen > 0) { mReadingLength = false; mAStream.Read(msgLen); } }
Paint Code 3/9 In .NET
Using Barcode encoder for ASP.NET Control to generate, create Code 3 of 9 image in ASP.NET applications.
Code 3 Of 9 Creator In VB.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Code 3 of 9 image in Visual Studio .NET applications.
UPC-A Creator In .NET
Using Barcode creator for .NET Control to generate, create UPC-A Supplement 2 image in VS .NET applications.
International Standard Serial Number Generation In .NET
Using Barcode creator for .NET framework Control to generate, create International Standard Serial Number image in VS .NET applications.
Paint Bar Code In Java
Using Barcode generation for Java Control to generate, create bar code image in Java applications.
Bar Code Generator In C#
Using Barcode printer for .NET Control to generate, create barcode image in Visual Studio .NET applications.
Making ANSI/AIM Code 128 In VB.NET
Using Barcode generator for Visual Studio .NET Control to generate, create Code 128 Code Set A image in VS .NET applications.
Scanning Code 128 Code Set A In .NET
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.