WCF Communication Objects states Cheat Sheet

WCF is all about communication objects – channels, listeners, factories, all implement the ICommunicationObject interface (some through the CommunicationObject class). This provides a base implementation for the basic state machine states and transitions common to all communication-oriented object.

At any given point in time, the communication objects find themselves in a CommunicationState. Here is a diagram with the states and the transitions:

When we look at a communication object in a debugger, we see something like this (some columns and internal objects removed for brevity reasons):

Name: System.ServiceModel.Channels.ServiceChannel

Fields:

Type	VT	Value	Name
System.Boolean	1	0	aborted
System.Boolean	1	0	closeCalled
System.Boolean	1	0	onClosingCalled
System.Boolean	1	0	onClosedCalled
System.Boolean	1	1	onOpeningCalled
System.Boolean	1	1	onOpenedCalled
System.Boolean	1	0	raisedClosed
System.Boolean	1	0	raisedClosing
System.Boolean	1	0	raisedFaulted
System.Boolean	1	0	traceOpenAndClose
System.Object	0	000000000131d8e0	eventSender
System.Int32	1	2	state
System.EventHandler	0	0	Closed
System.EventHandler	0	0	Closing
System.EventHandler	0	0	Faulted
System.EventHandler	0	0	Opened
System.EventHandler	0	0	Opening

In our example, the communication object is in state 2. How does that translate to the actual states? To tell you the truth, I always take some time to map the number to the state, so I started using this cheat sheet:

public enum CommunicationState
{
    Created = 0,
    Opening = 1,
    Opened = 2,
    Closing = 3,
    Closed = 4,
    Faulted = 5
}

So in our case, the ServiceChannel is Opened. We could identify the state by looking at the other variable – if close called or aborted was called, we can only by in state 4 or 5 and so on. But the cheat sheet makes it simple.

Hope you find it useful!

Comments

• Anonymous
  May 30, 2010
  Didnt i say communication objects like  for an examplet.v, internet, texting, sonar noise and all that.