How does WCF Message.ToString() method work?

Question

All of the methods on System.ServiceModel.Channels.Message only allow you to read the message body once, and fail with an exception if called after the message has been read. The msdn documentation confirms that it is only possible to read a message body one. However, if you call ToString() on an already read message, you appear to get back the entire soap envelope, body and all.

So in my case it would seem to be possible to access the body even after it has been read if only the methods would allow it.

Is there something I'm missing here? Is using ToString() as a work-around to get the body not reliable in some situations?

In my case, I'm working on some error logging for some WCF operations and an getting the original message from OperationContext.RequestContext.RequestMessage. I'm logging the message with ToString() because that is the only way I can find to allow me to log the message body.

Answer 1

ToString may print the message body, but that's not guaranteed. There are many types of Message objects (it's an abstract class). Some of them buffer the whole body, while others only have a forward-only reader over it. The message implementations which buffer the message may write the body when ToString is called, and that's what you're seeing. But this is not guaranteed for all message types. In many cases, the body is simply written as "...stream..." when ToString is called.