Pipeline

Now it is time to take a closer look at the container's core request processing element.

As we have seen already, an org.apache.catalina.Pipeline represents a series of filters, each of which is represented by an org.apache.catalina.Valve instance, that a request must pass through on its way into a Container, and that a response must pass through on its way out of that Container.

Pipeline execution scope

A pipeline's scope is determined by the container within which it is nested. The pipeline associated with an engine is invoked by the CoyoteAdapter, at the boundary between the connector subsystem and the Catalina engine. As a result, it will process every request that is received by any connector associated with that engine. In other words, an engine's pipeline can be said to have a global scope.

A pipeline associated with a host is invoked by the engine when it hands off processing to the appropriate host for which the request was targeted. As a result, a host's pipeline will process...