As described below, one of key component of the Jetspeed-2 portal engine is its request pipeline.
			

			In Jetspeed-2 request are processed through a series of Valve assembled together as a
			pipeline.  
			
In Jetspeed-2, a request pipeline performs individual operations to the request.
            A Pipeline is made of Valves chained together in a chain of responsibility pattern.
            The JetspeedPipeline implementation assembles a ordered list of Valves that are
            processed sequentially.
            


            Jetspeed-2 provides various type of Valve as illustrated below:

			The above valves serve the following purpose:
           	
| Valve Name | Description | 
|---|---|
| ActionValve | Check if PortletActionneeds to be processed and process it, if required.
            		Used in the portlet pipeline. | 
| AggregateValve | Invokes all Layout components in render mode to aggregate the generated contents and send the result to the client. | 
| CapabilityValve | Identifies the browser and adds a CapabilityMapto theRequestContext. | 
| CleanupValve | Looks for JSP pages that were pushed onto the org.apache.jetspeed.renderStackrequest attribute, and attempts to include them. | 
| LoginValidationValve | Checks if a login attempt failed and determines the cause. | 
| PasswordCredentialValve | Checks the PasswordCredential (only once) after a User is logged in and redirects to a change password page if necessary. | 
| SecurityValve | Authenticates the user or redirects to Login if necessary, adds the
					authenticated Subject to the RequestContext. |