Comunication from Server to Client. How trigger the Client?

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Hi, i hope this is not a repeated question.
I'll show you the problem.
I've an application WPF Client, and an application WPF Server.

Sometimes, during the life of this comunication, Server should send data to Client(without client asked nothing, i know it's strange, and i don't know if it's possible).

Is possible to have a mechanism that triggers an event in the Client when in the Stream
there is the data sent by Server??

Thanks for help, i hope i have explained the problem clearly!

Posted 24-Sep-14 4:33am

Member 11068876

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ZurdoDev 24-Sep-14 10:44am

It's been a long time since I've done it but you can use sockets and essentially the client is always listening on the port that the server sends on. You can't force something from the server to the client for security reasons, your client needs to be listening and then you write code to respond. Look into .Net and sockets.

Member 11068876 24-Sep-14 11:04am

thanks for the answer.
The problem is that i don't want that Client is always listening .
But if it is a rule, i've to change completely mechanism.

Richard MacCutchan 24-Sep-14 11:56am

If the client is not listening then you cannot communicate with it. That's the way sockets work.

ZurdoDev 24-Sep-14 14:02pm

1. Please reply to comments so that the user is notified.
2. Can you imagine being able to push something to the client without them listening? First, how would that even happen. Second, what a huge security risk because I could give everyone a virus without them even doing anything.

Sergey Alexandrovich Kryukov 24-Sep-14 16:01pm

In fact I found that this question, despite some problems in formulation (why WPF?), very important. So I up-voted it and tried to answer.
—SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2014-09-24T09:58:00

Formally speaking, pure client-server model assumes that the client is never triggered. Everything is executed by the initiative from the client side: client sends request to the server, and the server only takes the request and sends the response.

But 1) this model is so amazingly limiting that I suspect its domination is rooted in the conceptually mistaken thinking of many players in the industry; 2) it looks like you; despite of using of the term "client" and "server" in fact is looking for a way to go far away from this limiting model. And I really appreciate that you do. In fact, much more advanced models are known (such as publisher-subscriber, "server push"), but, regretfully, they were somewhat stalled, perhaps by the domination of the client-server.

So, your question raises very important issue, even the class of issues: pull technology vs. push technology:
http://en.wikipedia.org/wiki/Pull_technology[^],
http://en.wikipedia.org/wiki/Push_technology[^].

Please see my past answer: Application 'dashboard' for website accounts[^].

Further detail strongly depend on the technologies and standard you use or want to use. (And WPF it totally irrelevant here. Or, maybe you meant to mention WFC?)
If your communication layer is pretty much custom (for example, based purely on TCP), having the client part triggered would be fairly easy. Please see my past answers:
^] (anchor is broken, but the link should work; please see below),
Multple clients from same port Number[^].

(We are experiencing problem with CodeProject links in the posts. First anchor above is broken. Please use:
"http://www.codeproject.com/Answers/536542/anplusamateurplusquestionplusinplussocketplusprogr#answer2".
You have to copy and paste this URL to the browser yourself. Sorry for the inconvenience.)

—SA