All communication to a COM or Script component implementation is synchronous. If you want to create a communication flow to a port that uses a COM component or Script component implementation, you must use the Method Communication Wizard.

All communication to an unbound port, or to a Message Queuing or BizTalk Messaging implementation is asynchronous. If you want to create a communication flow to a port that uses a Message Queuing or BizTalk Messaging implementation, or if you want to create a communication flow to an unbound port, you must use the XML Communication Wizard.

The following illustration and text describes what an XLANG schedule does for the four possible communication actions.

No
wait

Wait

Wait

Wait

2

Asynchronous send action

Synchronous send action

Asynchronous receive action

Synchronous receive action

1

3

4

4

3

2

1

Wait

Another
application

XLANG
schedule

Com or Script component

Message Queuing or Biztalk Messaging

1. Synchronous receive action
   1. The XLANG schedule waits for another application to send a method request and instantiate a component.
      
      
   2. The schedule intercepts the method request.
      
      
   3. The schedule waits for the component to return the method response.
      
      
   4. The schedule intercepts the method response.
      
      
   5. The schedule continues with the next action in the business process flow.
2. Synchronous send action
   1. The XLANG schedule initiates the method request and instantiates the component.
      
      
   2. The schedule waits for the component to return the method response.
      
      
   3. The schedule receives the method response.
      
      
   4. The schedule continues with the next action in the business process flow.
3. Asynchronous receive action
   1. The XLANG schedule waits for another application to send a message to a messaging queue or to a BizTalk Messaging channel.
      
      
   2. The XLANG schedule receives the message from the messaging queue or from the channel.
      
      
   3. The schedule continues with the next action in the business process flow.
4. Asynchronous send action
   1. The XLANG schedule sends a message to a messaging queue or to a BizTalk Messaging channel.
      
      
   2. The schedule continues with the next action in the business process flow.
      
      
   3. Another application receives the message from the message queue or BizTalk Messaging channel.

Notes

• A special case exists for the synchronous receive action. If you choose No instantiation in the COM or Script Component Binding Wizard, the component is not instantiated, and no code for the method call is executed. Instead, when the XLANG schedule intercepts the method request information, it returns this information as the response. The method call is circumvented. For more information about static and dynamic ports and the COM and Script Component Binding Wizards, see the following topics:
  • Static and Dynamic Ports
    
    
  • Implement Ports
    
    
  • Using the COM Component Shape
    
    
  • Using the Script Component Shape
• Action events related to messages processed by an XLANG schedule that are either sent to or received from BizTalk Messaging Services can be tracked in the Tracking database. For more information, see Tracking XLANG schedule events in the Tracking database.

This section contains information about the following topics:

• Using the Method Communication Wizard
  
  
• Synchronous Communication
  
  
• Using the XML Communication Wizard
  
  
• Asynchronous Communication

Related Topics