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SQL Anywhere 10.0.1 » MobiLink - Server Administration » Writing Synchronization Scripts in .NET » Writing .NET synchronization logic

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User-defined start classes


You can define start classes that are loaded automatically when the server is started. The purpose of this feature is to allow you to write .NET code that executes at the time the MobiLink server starts the CLR—before the first synchronization. This means you can create connections or cache data before the first user synchronization request in the server instance.

You do this with the MLStartClasses option of the mlsrv10 -sl dnet option. For example, the following is part of a mlsrv10 command line. It causes mycl1 and mycl2 to be loaded as start classes.

-sl dnet(-MLStartClasses=MyNameSpace.MyClass.mycl1,MyNameSpace.MyClass.mycl2)

Classes are loaded in the order in which they are listed. If the same class is listed more than once, more than one instance is created.

All start classes must be public and must have a public constructor that either accepts no arguments or accepts one argument of type MobiLink.Script.ServerContext.

The names of loaded start classes are output to the MobiLink log with the message "Loaded .NET start class: classname".

For more information about .NET CLR, see -sl dnet option.

To see the start classes that are constructed at server start time, see GetStartClassInstances method.

Example

Following is a template start class. It starts a daemon thread that processes events and creates a database connection. (Not all start classes will need to create a thread but if a thread is spawned it should be a daemon thread.)

using System;
using System.IO;
using System.Threading;
using iAnywhere.MobiLink.Script;
namespace TestScripts {
  public class MyStartClass {
    ServerContext    _sc;
    bool             _exit_loop;
    Thread           _thread;
    OdbcConnection   _conn;
    public MyStartClass( ServerContext sc ) {
      // Perform setup first so that an exception will
      // cause MobiLink startup to fail.
      _sc          = sc;
      // Create connection for use later.
      _conn        = _sc.makeConnection();
      _exit_loop   = false;
      _thread      = new Thread( new ThreadStart( run ) ) ;
      _thread.IsBackground = true;
      _thread.Start();
    }
    public void run() {
      ShutdownCallback callback = new ShutdownCallback( shutdownPerformed );
      _sc.ShutdownListener += callback;
      // run() can't throw exceptions.
      try {
        handlerLoop();
        _conn.close();
        _conn = null;
      } catch( Exception e ) {
        // Print some error output to the MobiLink log.
        Console.Error.Write( e.ToString() );
        // There is no need to be notified of shutdown.
        _sc.ShutdownListener -= callback;
        // Ask server to shut down so this fatal error will
        // be fixed.
        _sc.Shutdown();
      }
      // Shortly after return, this thread will no longer
      // exist.
      return;
    }
    public void shutdownPerformed( 
      ServerContext sc ) {
      // Stop the event handler loop.
      try {
        _exit_loop = true;
        // Wait a maximum of 10 seconds for thread to die.
        _thread.Join( 10*1000 );
      } catch( Exception e ) {
        // Print some error output to the MobiLink log.
        Console.Error.Write( e.ToString() );
      }
    }
    private void handlerLoop() {
      while( !_exit_loop ) {
        // Handle events in this loop.
        Thread.Sleep( 1*1000 );
      }
    }
  }
}