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Java > Open Source Codes > org > apache > turbine > Pipeline


1 package org.apache.turbine;
2
3 /* ====================================================================
4  * The Apache Software License, Version 1.1
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10  * modification, are permitted provided that the following conditions
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14  * notice, this list of conditions and the following disclaimer.
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21  * 3. The end-user documentation included with the redistribution,
22  * if any, must include the following acknowledgment:
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25  * Alternately, this acknowledgment may appear in the software itself,
26  * if and wherever such third-party acknowledgments normally appear.
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29  * "Apache Turbine" must not be used to endorse or promote products
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34  * "Apache Turbine", nor may "Apache" appear in their name, without
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50  *
51  * This software consists of voluntary contributions made by many
52  * individuals on behalf of the Apache Software Foundation. For more
53  * information on the Apache Software Foundation, please see
54  * <http://www.apache.org/>.
55  */
56
57 import java.io.IOException JavaDoc;
58
59 /**
60  * The idea of a pipeline is being taken from Catalina
61  * in its entirety :-)
62  *
63  * I would like to take the idea further and implement
64  * Valves instead of hardcoding particular methods
65  * in a pipeline.
66  *
67  * It would be more flexible to specify Valves for
68  * a pipeline in an XML file (we can also rip off the
69  * digester rules from T4) and have invoke() as part
70  * of the interface.
71  *
72  * So a set of Valves would be added to the pipeline
73  * and the pipeline would 'invoke' each valve. In the
74  * case Turbine each Valve would produce some output
75  * to be sent out the pipe. I think with another days
76  * work this can be fully working. The first pipeline
77  * to be fully implemented will the ClassicPipeline
78  * will emulate the Turbine 2.1 way of doing things.
79  *
80  * @author <a HREF="mailto:jvanzyl@apache.org">Jason van Zyl</a>
81  * @author <a HREF="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
82  */
83 public interface Pipeline
84 {
85     /**
86      * Initializes this instance. Called once by the Turbine servlet.
87      */
88     public void initialize()
89         throws Exception JavaDoc;
90
91     /**
92      * <p>Add a new Valve to the end of the pipeline.</p>
93      *
94      * @param valve Valve to be added.
95      *
96      * @exception IllegalStateException If the pipeline has not been
97      * initialized.
98      */
99     public void addValve(Valve valve);
100
101     /**
102      * Return the set of all Valves in the pipeline. If there are no
103      * such Valves, a zero-length array is returned.
104      *
105      * @return An array of valves.
106      */
107     public Valve[] getValves();
108
109     /**
110      * <p>Cause the specified request and response to be processed by
111      * the sequence of Valves associated with this pipeline, until one
112      * of these Valves decides to end the processing.</p>
113      *
114      * <p>The implementation must ensure that multiple simultaneous
115      * requests (on different threads) can be processed through the
116      * same Pipeline without interfering with each other's control
117      * flow.</p>
118      *
119      * @param data The run-time information, including the servlet
120      * request and response we are processing.
121      *
122      * @exception IOException an input/output error occurred.
123      */
124     public void invoke(RunData data)
125         throws TurbineException, IOException JavaDoc;
126
127     /**
128      * Remove the specified Valve from the pipeline, if it is found;
129      * otherwise, do nothing.
130      *
131      * @param valve Valve to be removed.
132      */
133     public void removeValve(Valve valve);
134 }
135
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