dotConnect for Dynamics 365 Documentation
Asynchronous Query Execution

dotConnect for Dynamics 365 supports a very useful feature - asynchronous execution of methods that take most of time in database applications. Traditionally, the main thread of the application went blocked during opening a connection, transferring large blocks of data, and other operations alike. Now you can entrust execution of a query to a background thread and concentrate on performing other operations, for example, an update of user interface elements, or on a preparation of another query for execution.

The article consists of following sections:

Understanding Asynchronous Methods

dotConnect for Dynamics 365 provides you with asynchronous methods for most of the time-consuming operations: connecting, data retrieving, and DML statement execution. For every synchronous method two asynchronous methods are implemented, with prefixes "Begin" and "End" respectively. The table below summarizes the new methods in the command object:

Table 1. Asynchronous methods

Class

Synchronous method

Asynchronous methods

Begin part End part
DynamicsConnection Open BeginOpen EndOpen
DynamicsCommand ExecuteReader BeginExecuteReader EndExecuteReader
DynamicsCommand ExecuteNonQuery BeginExecuteNonQuery EndExecuteNonQuery

A typical usage of asynchronous methods looks like the following code.

IAsyncResult myResult = myCommand.BeginExecuteNonQuery(null, null);
...
rowsAffected = myCommand.EndExecuteNonQuery(myResult);
Dim myResult As IAsyncResult = myCommand.BeginExecuteNonQuery(Nothing, Nothing)
...
Dim rowsAffected As Int32 = myCommand.EndExecuteNonQuery(myResult)


First, application calls the "Begin" method and passes it all the parameters needed to accomplish the task. This method returns IAsyncResult object that represents the operation invoked and is used for later processing. After the process has been invoked, application can proceed to do its job.
Later, when the query has finished its execution, application calls the "End" method, passing it IAsyncResult object returned by the "Begin" method that has been invoked earlier.
If something goes wrong with the query, the exception is thrown only when application calls "End" method.

Completion Signalling

The common synchronous method calls do not return until the operation is finished. In the asynchronous cases, the begin call returns immediately, so there is a need to determine when the operation is actually complete. dotConnect for Dynamics 365 provides you with three ways to catch the query termination.

All of the methods listed in the table 1 accept at least two parameters. For example, DbCommandBase.BeginExecuteReader method is declared in the following way:

public IAsyncResult BeginExecuteReader(
   AsyncCallback callback,
   object stateObject,
   CommandBehavior behavior
);
Public Function BeginExecuteReader( _
   ByVal callback As AsyncCallback, _
   ByVal stateObject As Object, _
   ByVal behavior As CommandBehavior _
) As IAsyncResult

The way you get signalled about query termination depends on what values you pass to the "Begin" method.

In either case you must call corresponding "End" method to continue using the connection that serves the operation. If you try to start another asynchronous operation on connection that already serves a "Begin" method, an exception will be thrown. If you do not call the corresponding "End" method, some system resources may leak. Note that calling the "End" method without waiting for the operation to complete is allowed. In this case the method will block the current thread until the operation finishes.

Every asynchronous method that invokes an operation has stateObject parameter. You can pass it any object you find useful thus providing the callback routine any information it may require. The value of stateObject is accessible through IAsyncResult.AsyncState property.

Samples

A sample is provided below for each of the signalling methods.

The following sample starts an asynchronous execution of UPDATE statement, then periodically checks whether the operation is complete, while performing some operations (writes a dot to console). Once query is done, the routine returns and application is ready to close.

using System;
using Devart.Data.Dynamics;

namespace MyNamespace
{
  class Class1
  {
    static DynamicsConnection myConnection = new DynamicsConnection(
      "Server=https://your_company.crm4.dynamics.com;User Id=Test@Test.onmicrosoft.com;Password=A123456789;");
    static DynamicsCommand myCommand = new DynamicsCommand(
      "UPDATE Contact SET Department = 'Development' WHERE LastName = 'sample name 1'");

    static void PerformAsync()
    {
      myCommand.Connection = myConnection;
      myConnection.Open();
      int rowsAffected;
      try
      {
        IAsyncResult myResult = myCommand.BeginExecuteNonQuery(null, null);
        Console.Write("In progress...");
        while (!myResult.IsCompleted)
        {
          Console.Write(".");
          //Perform here any operation you need
        }
        rowsAffected = myCommand.EndExecuteNonQuery(myResult);
        Console.WriteLine();
        Console.WriteLine("Operation complete. Rows Affected: " + rowsAffected);
      }
      catch
      {
        Console.WriteLine("Error during execution.");
      }
      finally
      {
        myConnection.Close();
      }
    }

    static void Main(string[] args)
    {
      PerformAsync();
      Console.WriteLine("About to exit");
      Console.ReadLine();
    }
  }
}
Imports Devart.Data.Dynamics
Imports System

Module Module1

  Dim myConnection As New DynamicsConnection( _
      "Server=https://your_company.crm4.dynamics.com;User Id=Test@Test.onmicrosoft.com;Password=A123456789;")
  Dim myCommand As DynamicsCommand = New DynamicsCommand( _
    "UPDATE Contact SET Department = 'Development' WHERE LastName = 'sample name 1'")

  Public Sub PerformAsync()
    myCommand.Connection = myConnection
    myConnection.Open()
    Dim rowsAffected As Int32
    Try
      Dim myResult As IAsyncResult = myCommand.BeginExecuteNonQuery(Nothing, Nothing)
      Console.Write("In progress...")
      While Not myResult.IsCompleted
        Console.Write(".")
        'Perform here any operation you need
      End While
      rowsAffected = myCommand.EndExecuteNonQuery(myResult)
      Console.WriteLine()
      Console.WriteLine("Operation complete. Rows Affected: " & rowsAffected)
    Catch
      Console.WriteLine("Error during execution.")
    Finally
      myConnection.Close()
    End Try
  End Sub

  Sub Main()
    PerformAsync()
    Console.WriteLine("About to exit.")
    Console.ReadLine()
  End Sub

End Module

This method is very effective when several database operations can be executed simultaneously. The sample code opens two connections, then starts two asynchronous executions and waits for either to finish. Once an operation is signaled complete, the code processes results of the operation. Afterwards the application finishes the second operation. Using this method, we reduce query execution time from sum of two operations to the time of the slowest operation.

using System;
using Devart.Data.Dynamics;

namespace MyNamespace
{

  public class Class1
  {

    static void Main(string[] args)
    {
      //Set up objects required to execute the queries
      
      DynamicsConnection[] myConnections = new DynamicsConnection[2];
      DynamicsCommand[] myCommands = new DynamicsCommand[2];
      IAsyncResult[] aResults = new IAsyncResult[2];
      string conStr = "Server=https://your_company.crm4.dynamics.com;User Id=Test@Test.onmicrosoft.com;Password=A123456789;";
      myConnections[0] = new DynamicsConnection(conStr);
      myCommands[0] = new DynamicsCommand(
	    "UPDATE Contact SET Department = 'Development' WHERE LastName = 'sample name 1'", myConnections[0]);
      myConnections[1] = new DynamicsConnection(conStr);
      myCommands[1] = new DynamicsCommand(
	    "UPDATE Contact SET Department = 'Development' WHERE LastName = 'sample name 2'", myConnections[1]);
      try
      {
        //Open the connections
        myConnections[0].Open();
        myConnections[1].Open();
        //Invoke execution of both queries
        aResults[0] = myCommands[0].BeginExecuteNonQuery(null, null);
        aResults[1] = myCommands[1].BeginExecuteNonQuery(null, null);
        Console.WriteLine("Waiting for operations to complete...");
        //Wait for any of the queries to finish
        int ind = System.Threading.WaitHandle.WaitAny(new System.Threading.WaitHandle[] {
                                                             aResults[0].AsyncWaitHandle,
                                                             aResults[1].AsyncWaitHandle });
        //Process results of the query that finished first
        Console.WriteLine("Result #{0}: {1}", ind, 
		  myCommands[ind].EndExecuteNonQuery(aResults[ind]));
        //Process results of another query
        int anotherIndex = 1 - ind;
        Console.WriteLine("Result #{0}: {1}", (anotherIndex),
          myCommands[anotherIndex].EndExecuteNonQuery(aResults[anotherIndex]));
      }
      catch
      {
        Console.WriteLine("Error during a query.");
      }
      finally
      {
        myConnections[0].Close();
        myConnections[1].Close();
      }
      Console.WriteLine("About to exit");
      Console.ReadLine();
    }
  }
}
Imports System
Imports Devart.Data.Dynamics

Module Module1

  Sub Main()
    'Set up objects required to execute the queries
    Dim myConnections(1) As DynamicsConnection
    Dim myCommands(1) As DynamicsCommand
    Dim aResults(1) As IAsyncResult
    Dim conStr As String = "Server=https://your_company.crm4.dynamics.com;User Id=Test@Test.onmicrosoft.com;Password=A123456789;"
    myConnections(0) = New DynamicsConnection(conStr)
    myCommands(0) = New DynamicsCommand( _
	  "UPDATE Contact SET Department = 'Development' WHERE LastName = 'sample name 1'", myConnections(0))
    myConnections(1) = New DynamicsConnection(conStr)
    myCommands(1) = New DynamicsCommand( _
	  "UPDATE Contact SET Department = 'Development' WHERE LastName = 'sample name 2'", myConnections(1))
    Try
      'Open the connections
      myConnections(0).Open()
      myConnections(1).Open()
      'Invoke execution of both queries
      aResults(0) = myCommands(0).BeginExecuteNonQuery(Nothing, Nothing)
      aResults(1) = myCommands(1).BeginExecuteNonQuery(Nothing, Nothing)
      Console.WriteLine("Waiting for operations to complete...")
      Dim waitHandles() As System.Threading.WaitHandle = { _
	                          aResults(0).AsyncWaitHandle, aResults(1).AsyncWaitHandle}
      'Wait for any of the queries to finish
      Dim ind As Int32 = System.Threading.WaitHandle.WaitAny(waitHandles)
      'Process results of the query that finished first
      Console.WriteLine("Result #{0}: {1}", ind, _
	    myCommands(ind).EndExecuteNonQuery(aResults(ind)))
      'Process results of another query
      Dim anotherIndex As Int32 = 1 - ind
      Console.WriteLine("Result #{0}: {1}", (anotherIndex), _
        myCommands(anotherIndex).EndExecuteNonQuery(aResults(anotherIndex)))
    Catch
      Console.WriteLine("Error during a query.")
    Finally
      myConnections(0).Close()
      myConnections(1).Close()
    End Try
    Console.WriteLine("About to exit")
    Console.ReadLine()
  End Sub

End Module

This method is probably the most effective in many situations. The sample code initiates establishment of two connections. A connection itself is passed as stateObject parameter. This allows a delegate to know what connection has finished negotiation with user accounts and to end the asynchronous operation. Using this method, we obtain results of an operation once it is complete, without having to wait for the slower operations that might precede it.

using System;
using Devart.Data.Dynamics;

namespace MyNamespace
{
  class Class1
  {
        static string conStr = "Server=https://your_company.crm4.dynamics.com;User Id=Test@Test.onmicrosoft.com;Password=A123456789;";
        static DynamicsConnection myConnection1 = new DynamicsConnection(conStr);
        static DynamicsConnection myConnection2 = new DynamicsConnection(conStr);

    static void OperationComplete(IAsyncResult ar)
    {
      try
      {
        DynamicsConnection currentConnection = (DynamicsConnection)ar.AsyncState;
        currentConnection.EndOpen(ar);
        Console.WriteLine("Connection string: "+currentConnection.ConnectionString +
                           ", server version: "+currentConnection.ServerVersion);
      }
      catch
      {
        Console.WriteLine("Error during opening.");
      }
    }

    static void PerformAsync()
    {
      myConnection1.BeginOpen(new AsyncCallback(OperationComplete), myConnection1);
      myConnection2.BeginOpen(new AsyncCallback(OperationComplete), myConnection2);
      Console.WriteLine(
	    "Waiting for operations to complete. 
		Hit Enter when both connections are established.");
      Console.ReadLine();
      myConnection1.Close();
      myConnection2.Close();
    }

    static void Main(string[] args)
    {
      PerformAsync();
    }
  }
}
Imports System
Imports Devart.Data.Dynamics

Module Module1

    Dim connStr = "Server=https://your_company.crm4.dynamics.com;User Id=Test@Test.onmicrosoft.com;Password=A123456789;"
    Dim myConnection1 As New DynamicsConnection(connStr)
    Dim myConnection2 As New DynamicsConnection(connStr)

  Public Sub OperationComplete(ByVal ar As IAsyncResult)
    Try
      Dim currentConnection As DynamicsConnection = CType(ar.AsyncState, DynamicsConnection)
      currentConnection.EndOpen(ar)
      Console.WriteLine("Connection string: " & currentConnection.ConnectionString & _
                         ", server version: " & currentConnection.ServerVersion)
    Catch
      Console.WriteLine("Error during opening.")
    End Try
  End Sub

  Public Sub PerformAsync()
    myConnection1.BeginOpen(AddressOf OperationComplete, myConnection1)
    myConnection2.BeginOpen(AddressOf OperationComplete, myConnection2)
    Console.WriteLine( _
	  "Waiting for operations to complete. _
	    Hit Enter when both connections are established.")
    Console.ReadLine()
    myConnection1.Close()
    myConnection2.Close()
  End Sub

  Sub Main()
    PerformAsync()
  End Sub

End Module