Valve

A Valve is an atomic request processing component that is assembled into the Pipeline of a Container. The name Valve is a metaphor for a processing unit in a real world pipeline, where a valve controls and/or modifies what flows through it.

The org.apache.catalina.Valve interface defines methods for obtaining the next Valve in the pipeline; a backgroundProcess() method to execute a periodic task; and an invoke(Request, Response) method, which performs the actual processing associated with this valve.

A Valve may act on the request and response in a number of different ways, including:

• Examining and/or modifying the properties of the incoming request or outgoing response.

• Wrapping the request and/or response objects to supplement their functionality before passing them on.

• Completing its task and invoking the next Valve in the sequence, if any, by calling getNext().invoke() with the incoming Catalina Request and Response.

• Terminating request processing by generating and returning a complete...