Data-Driven Services with Silverlight 2

Posting Data to a RESTful Service

The previous sections demonstrated several different variations of building and invoking REST-friendly web services to retrieve data. All of the RESTful operations are decorated with the WebGet attribute, which indicates that they will be invoked with an HTTP GET. RESTful operations also support other HTTP methods, such as POST, PUT, and DELETE. However, Silverlight 2 is capable of directly issuing an HTTP GET or HTTP POST method only through managed code. You can invoke GET requests from Silverlight 2 using the WebClient class’s DownloadStringAsync method, and you can invoke POST requests using the UploadStringAsync method.

Note

There are creative ways to pass a PUT or DELETE from Silverlight 2, such as passing the HTTP PUT or DELETE method as a parameter in the X-HTTP-Method-Override header. This technique, which is referred to as POST Tunneling, allows a PUT or DELETE method to be sent in the X-HTTP-Method-Override header of an HTTP POST method. Many firewalls allow only GET or POST, so this technique is commonly used to issue GET, PUT, POST, and DELETE methods when the web service expects them.

Defining POST Methods

Creating a RESTful web service that accepts an HTTP POST request using WCF requires that the operation be decorated with the WebInvoke attribute instead of the WebGet attribute. The code in Example 9-18 demonstrates how to decorate a web service operation with the WebInvoke attribute to indicate that the HTTP method is a POST. The