InvokeServerMethodAsync(ServerMethodDelegate,CancellationToken,Object[]) Method

Asynchronously invokes the specified static (Shared in Visual Basic) method for execution on the server.

Syntax

Visual Basic
C#

'Declaration
 
Public Overloads Function InvokeServerMethodAsync( _
   ByVal serverMethod As ServerMethodDelegate, _
   ByVal cancellationToken As CancellationToken, _
   ByVal ParamArray userArguments() As Object _
) As Task(Of Object)

'Usage
 
Dim instance As EntityManager
Dim serverMethod As ServerMethodDelegate
Dim cancellationToken As CancellationToken
Dim userArguments() As Object
Dim value As Task(Of Object)
 
value = instance.InvokeServerMethodAsync(serverMethod, cancellationToken, userArguments)

public Task<object> InvokeServerMethodAsync( 
   ServerMethodDelegate serverMethod,
   CancellationToken cancellationToken,
   params object[] userArguments
)

Parameters

serverMethod: Method to be invoked
cancellationToken: CancellationToken
userArguments: Arguments to be passed to method

Exceptions

Exception	Description
System.InvalidOperationException	Invalid ServerMethodDelegate provided
System.ArgumentException	UserState token must be unique for the client
System.Security.SecurityException	Thrown if the method is not marked with the AllowRpcAttribute
PersistenceSecurityException	Thrown if the server method is decorated with a AuthorizationAttribute and fails authorization

Remarks

The method called must be marked with the AllowRpcAttribute and correspond to the ServerMethodDelegate signature.

InvokeServerMethodAsync enables a client-side caller to invoke an arbitrary static method on the server using an asynchronous call. An outstanding request can be canceled using the System.Threading.CancellationToken.

This feature is only available in certain editions of DevForce.

Example

// Sample showing asynchronous invocation of server method

// In client class:
private void MakeAsyncCall() {
  EntityManager mgr = new DomainModelEntityManager();
  // Make async call
  Guid myToken = Guid.NewGuid();
  mgr.InvokeServerMethodAsync(new ServerMethodDelegate(Order.GetNumberOfOrdersSlow), 
      InvokeServerMethodAsyncCompleted, myToken, 
 	    new DateTime(1995, 1, 1), new DateTime(1999, 1, 1));
}
private void InvokeServerMethodAsyncCompleted(InvokeServerMethodOperation e) {
  Guid token = (Guid)e.UserState;
  if (!e.Cancelled) {
     MessageBox.Show("my async result = " + Convert.ToInt32(e.Result).ToString());
  }
}

// Sample method defined in Order entity class:
public class Order {
//...

  // ServerMethodDelegate method, called from client
  [AllowRpc]
  public static Object GetNumberOfOrdersSlow(IPrincipal pPrincipal, EntityManager pMgr, params Object[] pArgs) {
     // Sleep to make this slower to show async
     System.Threading.Thread.Sleep(2000);
     DateTime dt1 = pArgs[0] as DateTime;
     DateTime dt2 = pArgs[1] as DateTime;
     return pMgr.Order.Where(o => o.OrderDate >= dt1 && o.OrderDate <= dt2).Count();
  }
}

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

EntityManager Class
EntityManager Members
Overload List