Persist a variable in WCF application per instance

Question

I am creating a WFC Restful service and there is a need to persist a variable that will be persist per user, is there a way I can achieve this without having to pass the variable to all my calls?

I am using trying to log the process of the user throughout the process, weather their request has failed or succeed, IP address, when they requested the action, failure time, etc. Please note I am new to WCF, thanks in advance.

Answer 1

I recently worked on this (except it wasn't RESTFUL). You could transmit information through HTTP headers and extract that information on the service-side. See http://trycatch.me/adding-custom-message-headers-to-a-wcf-service-using-inspectors-behaviors/

Answer 2

For the client ID itself I can suggest two places to put it. One is OperationContext.Current.IncomingMessageProperties . Another is CorrelationManager.StartLogicalOperation which allows you to define a logical operation - that could be the service request, beginning to end - or multiple operations - and retrieve a unique ID for each operation.

I would lean toward the latter because it's part of System.Diagnostics and can prevent dependencies on System.ServiceModel . (The name CorrelationManager even describes what you're trying to do.)

In either case I would look at interception. That's the ideal way to read the value (wherever you store it) without having to pollute the individual methods with knowledge of logging and client IDs. (I saw from your message that you're trying to avoid that direct dependency on client IDs.)

Here's some documentation on adding Windsor to your WCF service. (At some point I'll add some end-to-end documentation on my blog.) Then, when you're using Windsor to instantiate your services, you can also use it to instantiate the dependencies and put interceptors around them that will perform your logging before or after those dependencies do their work. Within those interceptors you can access or modify that stack of logical operations.

I'm not doing Windsor justice by throwing out a few links. I'd like to flesh it out with some blog posts. But I recommend looking into it. It's beneficial for lots of reasons - interception just one. It helps with the way we compose services and dependencies.

Update - I added a blog post - how to add Windsor to a WCF service in five minutes.