如何在服务器端检测客户端的超时异常？

Question

I am using synchronous WCF service which works well 99% of the time, but on some very rare occasions client times out before the server finishes processing. Is there a way to detect, on the SERVER side, that the client has timed out? I could use async operation, but in this case server-side timeout detection would save me quite a lot of work. I'm using net.tcp binding, if this matters.

Answer 1

For net.tcp, http, etc. in general no. (see comments above for some ideas; also it might be different for other protocols/bindings/etc.)

The reason is, that the WCF infrastructure code on the server side will not use the channel before it has finished executing the service operation's implementation code and marshalling the response. Only then it will attempt to send the response and at this point recognize that the connection has already been aborted by the client.

When the server gets that error the user code (your service operation implementation) is already done and thus you cannot react to that from there anymore. It might be possible from within a dispatcher, or other extension point, but personally I have not tried. However, that also would not save your server from unnecessary work, because as said, the client disconnect will still only be recognized when the server actually attempts to send the answer.

One "simple" way to mitigate such issues might be to split the work being done into several service operations/calls (if at all possible; and not accidentally introducing server-side state in the process). Or as others have said, have the client implement a "Ping" interface that the server can use to check if the client is still "alive" and the response is still needed.