Is there a built-in way to determine the size of a WCF response?

Question

Before a client gets the full payload of the web request, we'd like to first send it a measurement of the size of the response it will get. If the response will be too large, the client will present a message to the user giving them the option to abort the operation.

We can write some custom code to preload the response on the server, determine the size, and then pass it on to the client, but we'd rather not if there's another way to do it.

Does anyone know if WCF has any tricky way to do this? Or are there any free third party tools out there that will accomplish this?

Thanks.

Answer 1

I don't think there's anything "tricky" in WCF or the .NET framework to do this, really. What are you passing back to the client? An instance of a class?

What you could do is run the query or however you fetch the response, and then serialize that into a memory stream and see how big it gets. This won't be a totally accurate size - the SOAP messages has some overhead to it, like SOAP envelope and headers and stuff - but it can give you a ballpark figure of whether you're about to return a few hundred bytes, or a couple megabytes.

Trouble is: this might take a while on the server just to assemble / query, and then to actually "measure", too. Plus you'd almost have to have two calls - one to "MeasureResult" which returns an Int or Long or something, and then a second call "GetResult" to actually get the results. So you'll incur that effort to assemble the message twice....

I don't really have a good answer for you, but maybe you just need to figure out some other way to allow the client to abort a call if it takes too long. Or find a way to more quickly figure out an indicator as to how large the response will be (without getting all the details of the response itself).