SingingEels : Development Community & Resource

• Mar 06 2008 - 09:35:46 AM Timothy Khouri

  Well, I tried porting one of my recent WCF clients to Silverlight (which is basically my test to see how far Silverlight has come in the way of WCF and it's overall usefulness to me), and I'm sadly still a little disappointed.

  While it does have WCF support (and it also supports Sockets in the System.Net.Sockets namespace), it doesn't support the "DuplexClientBase" infrustructure.

  It does support "ClientBase", which is one-way WCF communications, but I really need to have the call back and OperationContext abilities of WCF in order for this to be a really "connected" application (as apposed to a "request-for-data" application).

  Let's see how Microsoft goes from here...

• Jul 29 2009 - 12:35:46 AM viserys

  I'd like to thank you first of all for your WCF articles - they've been invaluable.

  Do you know if Silverlight 3 is capable yet of using the DuplexClientBase structure? I'm designing a game with a Silverlight client (as you mentioned in your post), but I think I might need to change direction if not.

• Jul 29 2009 - 05:37:24 AM Timothy Khouri

  SL3 *does* support a duplex WCF model, however, it's not exactly the same as the standard WCF net.tcp duplex channel.

  The basic differences are that Silverlight will use a polling mechanism to achieve 2-way communications, and the other difference is that messages are fired asynchronously.

  It's going to be a slight learning curve using SL3 (especially if you haven't really gotten into Silverlight or WPF much yet), but I think it's worth it.

  Here's a blog post from earlier this year about SL3 and the duplex WCF stuff: http://blogs.msdn.com/silverlightws/archive/2009/03/20/what-s-new-with-web-services-in-silverlight-3-beta.aspx

• Jul 29 2009 - 12:37:14 PM viserys

  I'm a little bit concerned from my reading, as the Internet's abuzz with rumored scaling issues with PollingDuplex, poor responsiveness compared to TCP, etc. The MSDN documentation says that all methods in my service contract must be IsOneWay enabled, also, which will require me to rethink my design slightly.

  I might just go ahead with it (as a learning experience, if nothing else). Do you have any experience with the PollingDuplexBinding, especially with regards to something like a game? The closer to realtime the communication is, the better.

• Jul 30 2009 - 05:47:02 AM Timothy Khouri

  Personally, I haven't really done much with it... and there is always the option of using a straight TCP sockets. I would try to do the polling route and see how it goes. It may require you to rethink the messages you send to the client.

  Example: Instead of sending lots of separate "Bob moved by 1,2" commands, you could send an array of 'commands' that represent the current location of GameUsers in the area, where they are going, and the ETA (when then 'should' get there). This would allow you to smoothly animate player's movement on the client end.

  I hope it works out for you... If you don't have a blog already, you could blog your progress here on SingingEels. Maybe even write an article when it's all said and done :)

• Jul 30 2009 - 10:01:10 AM viserys

  Unfortunately, we decided last night to skip WCF for the Silverlight client and go with sockets. WCF seems very, very cool, and I'd like to work with it, but getting Silverlight to cooperate with a self-hosted duplex service is more trouble than it's worth at this point in time. I spent roughly all day reading up on it, and roughly all night trying to get it to work. No joy. :(

  We do have a blog, but it's not much to look at yet. I've been posting daily, but the project started only a few days ago. Might write that article you mentioned once we have something substantial, though!

  Thanks again for all of your input.

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