I have a simple WCF Service Library. And 3 projects that are using this WCF Service. These 3 projects each are doing one part of a job but not concurrently. I mean, When one is done, the second one starts, and when the second one is done, third one starts and this goes on.

I want my service to make the conversation between these 3 projects. So, when the first one is done, I want service to inform the second one that the first one is done and you can start. Is there any way to inform the these projects without using any function of the WCF Service periodically(without a trigger)?

Thank you.