Send some messages to client application from my WCF application

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C#

WCFServices

I am developing WCF Service. Once the client gives request, my service has to send some messages like Task 1 completed, Task 2 completed vise versa... and finally need to send response.

Up to now I am giving response to client perfectly. But I want to give processing information to the client while the client waiting for final response.

Technology used:

Client : DOTNET Application V3.5
Server : DOTNET WCF Services.
Bindings : Streamed request binding.

I am sorry if I was not able to explain clearly. Please help me regarding this.