My stackoverflow question was closed so here's a blog post about CoreWCF

Is there some kind of `IClosableStream` you can implement? That’d give you a `Closed` method, which you can then use to let either your server or stream know that it’s time to stop reading (or the stream reached EOF) - even if it’s done with a flag that’s set when the client disconnects.

Maybe there’s already an optional `Close` method you’re not overriding?

On the client side, randomStream.Close will get called when it's disposed.

On the server side, I'm not sure what I could put into an overriden Close that wouldn't just be base.Close()? RandomStream itself doesn't own any resources that need cleaning up.

I could force WCF to use Session mode, and then add flow-control through a side-channel, so other messages could prepare the stream to internally buffer and then rewrite in requested chunks?

But at that point I might as well just use an apprpriately sized GetRandomBlock(ValueWithSequence[]), and chunk requests that way and abandon using a stream for this at all.

I'll have an experiment with that approach to try to find the best buffer size and whether streaming the buffer actually helps vs just having it as the message and letting WCF control the sending.