public interface: Valve
A Valve is a request processing component associated with a
particular Container. A series of Valves are generally associated with
each other into a Pipeline. The detailed contract for a Valve is included
in the description of the
invoke() method below.
: The "Valve" name was assigned to this concept
because a valve is what you use in a real world pipeline to control and/or
modify flows through it.
Craig - R. McClanahan
Gunnar - Rjnning
Peter - Donald
$ - Revision: 796156 $ $Date: 2009-07-21 08:29:47 +0200 (Tue, 21 Jul 2009) $
|Method from org.apache.catalina.Valve Detail:|
public void backgroundProcess()
Execute a periodic task, such as reloading, etc. This method will be
invoked inside the classloading context of this container. Unexpected
throwables will be caught and logged.
public void event(Request request,
CometEvent event) throws IOException, ServletException
public String getInfo()
Return descriptive information about this Valve implementation.
public Valve getNext()
Return the next Valve in the pipeline containing this Valve, if any.
public void invoke(Request request,
Response response) throws IOException, ServletException
Perform request processing as required by this Valve.
An individual Valve MAY perform the following actions, in
the specified order:
- Examine and/or modify the properties of the specified Request and
- Examine the properties of the specified Request, completely generate
the corresponding Response, and return control to the caller.
- Examine the properties of the specified Request and Response, wrap
either or both of these objects to supplement their functionality,
and pass them on.
- If the corresponding Response was not generated (and control was not
returned, call the next Valve in the pipeline (if there is one) by
- Examine, but not modify, the properties of the resulting Response
(which was created by a subsequently invoked Valve or Container).
A Valve MUST NOT do any of the following things:
- Change request properties that have already been used to direct
the flow of processing control for this request (for instance,
trying to change the virtual host to which a Request should be
sent from a pipeline attached to a Host or Context in the
- Create a completed Response AND pass this
Request and Response on to the next Valve in the pipeline.
- Consume bytes from the input stream associated with the Request,
unless it is completely generating the response, or wrapping the
request before passing it on.
- Modify the HTTP headers included with the Response after the
getNext().invoke() method has returned.
- Perform any actions on the output stream associated with the
specified Response after the
getNext().invoke() method has
public void setNext(Valve valve)
Set the next Valve in the pipeline containing this Valve.