URI templates provide an efficient syntax for expressing large sets of structurally similar URIs. For example, the following template expresses the set of all three-segment URIs that begin with "a" and end with "c" without regard to the value of the intermediate segment: a/{segment}/c

This template describes URIs like the following:

• a/x/c
  
• a/y/c
  
• a/z/c
  
• and so on.
  

In this template, the curly brace notation ("{segment}") indicates a variable segment instead of a literal value.

.NET Framework 3.5 provides a new API for working with URI templates called UriTemplate. UriTemplates allow you to do the following:

• You can call one of the Bind methods with a set of parameters to produce a fully-closed URI that matches the template. This means all variables within the URI template are replaced with actual values.
  
• You can call Match() with a candidate URI, which uses a template to break up a candidate URI into its constituent parts and returns a dictionary that contains the different parts of the URI labeled according to the variables in the template.
  
• Bind() and Match() are inverses so that you can call Match( Bind( x ) ) and come back with the same environment you started with.
  

There are many times (especially on the server, where dispatching a request to a service operation based on the URI is necessary) that you want to keep track of a set of UriTemplate objects in a data structure that can independently address each of the contained templates. UriTemplateTable represents a set of URI templates and selects the best match given a set of templates and a candidate URI. This is not affiliated with any particular networking stack (WCF included) so you can use it wherever necessary.

The WCF Service Model makes use of UriTemplate and UriTemplateTable to associate service operations with a set of URIs described by a UriTemplate. A service operation is associated with a UriTemplate, using either the WebGetAttribute or the WebInvokeAttribute.

Web-style services can be called from a Web browser by typing a URL that is associated with a service operation. These service operations may take parameters which must be specified in a string form within the URL. The following table shows the types that can be passed within a URL and the format used.

Web-style services make use of retrieval verbs (for example HTTP GET) in addition to various invoke verbs (for example HTTP POST, the verb used by SOAP services). The Web Programming Model allows service developers to control the both the URI template and verb associated with their service operations with the WebGetAttribute and WebInvokeAttribute. The WebGetAttribute and the WebInvokeAttribute allow you to control how individual operations get bound to URIs and the HTTP methods associated with those URIs. For example, adding WebGetAttribute and WebInvokeAttribute in the following code.

[ServiceContract]
interface ICustomer
{
  //"View It"
  [OperationContract]
  [WebGet]
  Customer GetCustomer():
  
  //"Do It"
  [OperationContract]
  [WebInvoke]
  Customer UpdateCustomerName( string id, 
                               string newName );
}

The preceding code allows you to make the following HTTP requests.

GET /GetCustomer

POST /UpdateCustomerName

WebInvokeAttribute defaults to POST but you can use it for other verbs too.

[ServiceContract]
interface ICustomer
{
  //"View It“ -> HTTP GET
  [OperationContract]
  [WebGet( UriTemplate=“customers/{id}” )]
  Customer GetCustomer( string id ):
  
  //"Do It“ -> HTTP PUT
  [OperationContract]
  [WebInvoke( UriTemplate=“customers/{id}”, Method=“PUT” )]
  Customer UpdateCustomer( string id, Customer newCustomer );
}

Formats and the Web Programming Model

Concepts

Other Resources