Pipeline (Catalina Internal API Documentation)

org.apache.catalina
Interface Pipeline

All Known Implementing Classes:

ContainerBase, StandardPipeline

public interface Pipeline

Interface describing a collection of Valves that should be executed in sequence when the invoke() method is invoked. It is required that a Valve somewhere in the pipeline (usually the last one) must process the request and create the corresponding response, rather than trying to pass the request on.

There is generally a single Pipeline instance associated with each Container. The container's normal request processing functionality is generally encapsulated in a container-specific Valve, which should always be executed at the end of a pipeline. To facilitate this, the setBasic() method is provided to set the Valve instance that will always be executed last. Other Valves will be executed in the order that they were added, before the basic Valve is executed.

Version:

$Revision: 1.4 $ $Date: 2001/07/22 20:13:30 $

Author:

Craig R. McClanahan, Peter Donald

Method Summary

void	addValve(Valve valve) Add a new Valve to the end of the pipeline associated with this Container.
Valve	getBasic() Return the Valve instance that has been distinguished as the basic Valve for this Pipeline (if any).
Valve[]	getValves() Return the set of Valves in the pipeline associated with this Container, including the basic Valve (if any).
void	invoke(Request request, Response response) Cause the specified request and response to be processed by the Valves associated with this pipeline, until one of these valves causes the response to be created and returned.
void	removeValve(Valve valve) Remove the specified Valve from the pipeline associated with this Container, if it is found; otherwise, do nothing.
void	setBasic(Valve valve) Set the Valve instance that has been distinguished as the basic Valve for this Pipeline (if any).

Method Detail

getBasic

public Valve getBasic()

Return the Valve instance that has been distinguished as the basic Valve for this Pipeline (if any).

setBasic

public void setBasic(Valve valve)

Set the Valve instance that has been distinguished as the basic Valve for this Pipeline (if any). Prioer to setting the basic Valve, the Valve's setContainer() will be called, if it implements Contained, with the owning Container as an argument. The method may throw an IllegalArgumentException if this Valve chooses not to be associated with this Container, or IllegalStateException if it is already associated with a different Container.

Parameters:

valve - Valve to be distinguished as the basic Valve

addValve

public void addValve(Valve valve)

Add a new Valve to the end of the pipeline associated with this Container. Prior to adding the Valve, the Valve's setContainer() method will be called, if it implements Contained, with the owning Container as an argument. The method may throw an IllegalArgumentException if this Valve chooses not to be associated with this Container, or IllegalStateException if it is already associated with a different Container.

Parameters:

valve - Valve to be added

Throws:

java.lang.IllegalArgumentException - if this Container refused to accept the specified Valve

java.lang.IllegalArgumentException - if the specifie Valve refuses to be associated with this Container

java.lang.IllegalStateException - if the specified Valve is already associated with a different Container

getValves

public Valve[] getValves()

Return the set of Valves in the pipeline associated with this Container, including the basic Valve (if any). If there are no such Valves, a zero-length array is returned.

invoke

public void invoke(Request request,
                   Response response)
            throws java.io.IOException,
                   javax.servlet.ServletException

Cause the specified request and response to be processed by the Valves associated with this pipeline, until one of these valves causes the response to be created and returned. The implementation must ensure that multiple simultaneous requests (on different threads) can be processed through the same Pipeline without interfering with each other's control flow.

Parameters:

request - The servlet request we are processing

response - The servlet response we are creating

Throws:

java.io.IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet exception is thrown

removeValve

public void removeValve(Valve valve)

Remove the specified Valve from the pipeline associated with this Container, if it is found; otherwise, do nothing. If the Valve is found and removed, the Valve's setContainer(null) method will be called if it implements Contained.

Parameters:

valve - Valve to be removed