xref: /unit/src/java/nginx/unit/websocket/Transformation.java (revision 1157:7ae152bda303)
1 /*
2  *  Licensed to the Apache Software Foundation (ASF) under one or more
3  *  contributor license agreements.  See the NOTICE file distributed with
4  *  this work for additional information regarding copyright ownership.
5  *  The ASF licenses this file to You under the Apache License, Version 2.0
6  *  (the "License"); you may not use this file except in compliance with
7  *  the License.  You may obtain a copy of the License at
8  *
9  *      http://www.apache.org/licenses/LICENSE-2.0
10  *
11  *  Unless required by applicable law or agreed to in writing, software
12  *  distributed under the License is distributed on an "AS IS" BASIS,
13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  *  See the License for the specific language governing permissions and
15  *  limitations under the License.
16  */
17 package nginx.unit.websocket;
18 
19 import java.io.IOException;
20 import java.nio.ByteBuffer;
21 import java.util.List;
22 
23 import javax.websocket.Extension;
24 
25 /**
26  * The internal representation of the transformation that a WebSocket extension
27  * performs on a message.
28  */
29 public interface Transformation {
30 
31     /**
32      * Sets the next transformation in the pipeline.
33      * @param t The next transformation
34      */
setNext(Transformation t)35     void setNext(Transformation t);
36 
37     /**
38      * Validate that the RSV bit(s) required by this transformation are not
39      * being used by another extension. The implementation is expected to set
40      * any bits it requires before passing the set of in-use bits to the next
41      * transformation.
42      *
43      * @param i         The RSV bits marked as in use so far as an int in the
44      *                  range zero to seven with RSV1 as the MSB and RSV3 as the
45      *                  LSB
46      *
47      * @return <code>true</code> if the combination of RSV bits used by the
48      *         transformations in the pipeline do not conflict otherwise
49      *         <code>false</code>
50      */
validateRsvBits(int i)51     boolean validateRsvBits(int i);
52 
53     /**
54      * Obtain the extension that describes the information to be returned to the
55      * client.
56      *
57      * @return The extension information that describes the parameters that have
58      *         been agreed for this transformation
59      */
getExtensionResponse()60     Extension getExtensionResponse();
61 
62     /**
63      * Obtain more input data.
64      *
65      * @param opCode    The opcode for the frame currently being processed
66      * @param fin       Is this the final frame in this WebSocket message?
67      * @param rsv       The reserved bits for the frame currently being
68      *                      processed
69      * @param dest      The buffer in which the data is to be written
70      *
71      * @return The result of trying to read more data from the transform
72      *
73      * @throws IOException If an I/O error occurs while reading data from the
74      *         transform
75      */
getMoreData(byte opCode, boolean fin, int rsv, ByteBuffer dest)76     TransformationResult getMoreData(byte opCode, boolean fin, int rsv, ByteBuffer dest) throws IOException;
77 
78     /**
79      * Validates the RSV and opcode combination (assumed to have been extracted
80      * from a WebSocket Frame) for this extension. The implementation is
81      * expected to unset any RSV bits it has validated before passing the
82      * remaining RSV bits to the next transformation in the pipeline.
83      *
84      * @param rsv       The RSV bits received as an int in the range zero to
85      *                  seven with RSV1 as the MSB and RSV3 as the LSB
86      * @param opCode    The opCode received
87      *
88      * @return <code>true</code> if the RSV is valid otherwise
89      *         <code>false</code>
90      */
validateRsv(int rsv, byte opCode)91     boolean validateRsv(int rsv, byte opCode);
92 
93     /**
94      * Takes the provided list of messages, transforms them, passes the
95      * transformed list on to the next transformation (if any) and then returns
96      * the resulting list of message parts after all of the transformations have
97      * been applied.
98      *
99      * @param messageParts  The list of messages to be transformed
100      *
101      * @return  The list of messages after this any any subsequent
102      *          transformations have been applied. The size of the returned list
103      *          may be bigger or smaller than the size of the input list
104      */
sendMessagePart(List<MessagePart> messageParts)105     List<MessagePart> sendMessagePart(List<MessagePart> messageParts);
106 
107     /**
108      * Clean-up any resources that were used by the transformation.
109      */
close()110     void close();
111 }
112