Wrap MemoryStream in a using block REST WCF

Question

I'm learning REST to implement some Services with WCF. I implemented an example with a MemoryStream. Because MemoryStream is Disposable I wrapped it in a using. When I do this I sometimes can see the xml response in the browser (IE8) and sometimes it will just show me the following Errormessage:

The download of the specified resource has failed. Error processing resource 'http://localhost:8889/SimpleGetService/'.

Why does this occur? When I don't wrap it in a using, I never seem to get the error.

Answer 1

Sounds like it is being disposed before you stream it back to the response. Try getting the bytes from it as a byte array before disposing it and return the bytes.

Answer 2

In reality there is absolutely no need to Dispose a MemoryStream as it only uses managed resources. It inherits from Stream so it automatically gets the IDisposable interface, but it is not required.

Answer 3

When you return a Stream from a WCF REST service, don't dispose it (since it'll be disposed before the caller can ever do anything with it), just let the framework dispose it for you.

Answer 4

It seems to me that since the MemoryStream implements IDisposable, you should dispose it. Sure, it doesn't do anything TODAY, but it certainly could soemday!

You don't want your code to know the nitty-gritty details of making the REST call so maybe you should pull what you need out of the MemoryStream before the end of the using block and return that to your caller. That's more loosely-coupled anyway - returning a MemoryStream to your caller exposes too much of the details of the implementation IMHO.

Answer 5

You can set the OperationBehaviorAttribute.AutoDisposeParameters to true. This will take of your problem and dispose all returned objects.

Edit: Btw: this is set to true by default. So you should not have to worry about it at all anyway :)