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I was following this thread on the Silverlight forums and was asked to update the Duplex sample to Silverlight 4.

Click here to download the code.

More information about Duplex Services are available here:

• http://msdn.microsoft.com/en-us/library/cc645027(VS.95).aspx
• http://msdn.microsoft.com/en-us/library/ee844557(v=VS.95).aspx

Happy Silverlighting!

I’ve already blogged about the new Silverlight 3 Beta Duplex support here. In these days I’ve found some interesting articles and tips about this topic, so this is a list of links I’ve found useful:

• Improve PollingDuplex reliability with Silverlight 3.0 by Andrea Boschin
• Silverlight Tip: Problems with polling duplex inactivitytimeout. by Alexey Zakharov
• How to increase amount of silverlight duplex clients. by Alexey Zakharov
• Silverlight Tip: If Polling Duplex SLOWS Everything =) by Alexey Zakharov
• What’s new with web services in Silverlight 3 Beta by the Silverlight Web Services Team
• How to: Build a Duplex Service for a Silverlight Client
• How to: Access a Duplex Service

I’m testing the updated Duplex support available in Silverlight 3 Beta, the important news is the possibility to simplify and reduce the code in the client:

• now it’s possible to use the “Add Service Reference” functionality of Visual Studio to consume the service;
• in this way you the use of channels can be avoided by simply attaching a callback to an event.

I’ve prepared an example based on the material available on the official documentation, download the complete solution from here.

Great news:

• Binary message encoding;
• Duplex object model simplification;
• Faults support;
• New security mode;
• Command-line proxy generation.

Check out the original post by the Silverlight Web Services Team.

Remember also to download the samples available here.

The WCF REST Starter kit contains a set of new features that will be added to WCF 4.0 in order to simplify the development of RESTful Windows Communication Foundation Services and Clients.

This new release contains a set of new client-side features such as:

• a new HttpClient class to send Http requests and process the Http responses;
• a new “Paste Xml as Type“ add-in for Visual Studio to simplify the usage of the serialization capabilities offered by the new HttpClient.

Click here to read more information and download the installation package.

If you obtain this error using WCF, IIS7, LINQ to SQL on Windows 7, read this thread:

http://www.codetoday.net/default.aspx?g=posts&t=1595

Check out this excellent post by Tim Greenfield.

What is WS-Discovery? As described in this excellent post by Jesus Rodriguez, WS-Discovery is an OASIS Standard that defines a lightweight discovery mechanism for discovering services based on multicast messages. Read the post for an example of its use in WCF 4.0.

Yi-Lun Luo has posted a great example in the forum about creating RESTful WCF services, click here to read the complete thread.

Useful links:

• http://msdn2.microsoft.com/en-us/library/bb412169.aspx
• http://weblogs.asp.net/scottgu/pages/silverlight-tutorial-part-3-using-networking-to-retrieve-data-and-populate-a-datagrid.aspx

If you are interested in this subject, I also recommend the reading of this book by John Papa:

Suriel  Bendahan has written a great article about this topic on CodeProject, source code available!