One Shot Serialization

Why do some serialization errors when sending a response not result in a fault being returned to the client?

In the typical service operation, sending a response is comprised of returning the appropriate information from the service method to construct a message. You might think of that response as a single operation but performing the response is divided up into many different acts. As an example of a division you could make, one way to split a response into separate acts is to say that there is an act of thinking about whether to respond and what the response contains, an act of constructing the response, and an act of transmitting the response.

There is a moment in time during those acts in which the system moves from thinking about a response to actually carrying out the response. Because there are many different ways to divide the operation into a series of acts, that moment in time does not always make up a clear line separating one part of the system from another. However, if you get to the point where you've started carrying out the response, then you've attempted to respond. As an example in WCF terms, RequestContext.Reply is one key point at which the act of responding is realized.

There are a variety of different messaging patterns; the ones that you should be familiar with are the one-way, request-reply, and duplex patterns. One-way patterns don't have a response so we can ignore those in this discussion. Request-reply patterns have the property that for any given request there can only ever be one response. If you think about the act of responding now, then there is a point at which your single attempt to respond has fail. This point is totally divorced from what takes place on the wire. It instead is an internal artifact of how the particular system divides the response into acts. A failure before that point would permit an error response to be sent instead while a failure after that point means that no response can ever be sent.

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Comments

• Anonymous
  April 15, 2008
  Can I construct a proxy object on one machine and pass it to another? No, there's no concept in WCF of