https://tomcat.apache.org/: Tomcat Servlet Engine Core Classes and Standard implementations 
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 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.catalina;

import java.util.Set;


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.


Author:Craig R. McClanahan, Peter Donald
/**
 * <p>Interface describing a collection of Valves that should be executed
 * in sequence when the <code>invoke()</code> 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.</p>
 *
 * <p>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
 * <code>setBasic()</code> 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.</p>
 *
 * @author Craig R. McClanahan
 * @author Peter Donald
 */
public interface Pipeline extends Contained {

    
Returns:the Valve instance that has been distinguished as the basic
Valve for this Pipeline (if any).
/**
     * @return the Valve instance that has been distinguished as the basic
     * Valve for this Pipeline (if any).
     */
    public Valve getBasic();


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


Params:
  • valve – Valve to be distinguished as the basic Valve
/**
     * <p>Set the Valve instance that has been distinguished as the basic
     * Valve for this Pipeline (if any).  Prior to setting the basic Valve,
     * the Valve's <code>setContainer()</code> will be called, if it
     * implements <code>Contained</code>, with the owning Container as an
     * argument.  The method may throw an <code>IllegalArgumentException</code>
     * if this Valve chooses not to be associated with this Container, or
     * <code>IllegalStateException</code> if it is already associated with
     * a different Container.</p>
     *
     * @param valve Valve to be distinguished as the basic Valve
     */
    public void setBasic(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.


Implementation note: Implementations are expected to trigger the Container.ADD_VALVE_EVENT for the associated container if this call is successful.


Params:
  • valve – Valve to be added
Throws:
/**
     * <p>Add a new Valve to the end of the pipeline associated with this
     * Container.  Prior to adding the Valve, the Valve's
     * <code>setContainer()</code> method will be called, if it implements
     * <code>Contained</code>, with the owning Container as an argument.
     * The method may throw an
     * <code>IllegalArgumentException</code> if this Valve chooses not to
     * be associated with this Container, or <code>IllegalStateException</code>
     * if it is already associated with a different Container.</p>
     *
     * <p>Implementation note: Implementations are expected to trigger the
     * {@link Container#ADD_VALVE_EVENT} for the associated container if this
     * call is successful.</p>
     *
     * @param valve Valve to be added
     *
     * @exception IllegalArgumentException if this Container refused to
     *  accept the specified Valve
     * @exception IllegalArgumentException if the specified Valve refuses to be
     *  associated with this Container
     * @exception IllegalStateException if the specified Valve is already
     *  associated with a different Container
     */
    public void addValve(Valve valve);


    
Returns: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.
/**
     * @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.
     */
    public Valve[] getValves();


    
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.

Implementation note: Implementations are expected to trigger the Container.REMOVE_VALVE_EVENT for the associated container if this call is successful.


Params:
  • valve – Valve to be removed
/**
     * 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 <code>setContainer(null)</code> method
     * will be called if it implements <code>Contained</code>.
     *
     * <p>Implementation note: Implementations are expected to trigger the
     * {@link Container#REMOVE_VALVE_EVENT} for the associated container if this
     * call is successful.</p>
     *
     * @param valve Valve to be removed
     */
    public void removeValve(Valve valve);


    
Returns:the Valve instance that has been distinguished as the basic
Valve for this Pipeline (if any).
/**
     * @return the Valve instance that has been distinguished as the basic
     * Valve for this Pipeline (if any).
     */
    public Valve getFirst();


    
Returns true if all the valves in this pipeline support async, false otherwise

Returns:true if all the valves in this pipeline support async, false otherwise
/**
     * Returns true if all the valves in this pipeline support async, false otherwise
     * @return true if all the valves in this pipeline support async, false otherwise
     */
    public boolean isAsyncSupported();


    
Identifies the Valves, if any, in this Pipeline that do not support
async.

Params:
  • result – The Set to which the fully qualified class names of each
              Valve in this Pipeline that does not support async will be
              added
/**
     * Identifies the Valves, if any, in this Pipeline that do not support
     * async.
     *
     * @param result The Set to which the fully qualified class names of each
     *               Valve in this Pipeline that does not support async will be
     *               added
     */
    public void findNonAsyncValves(Set<String> result);
}