1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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7 * published by the Free Software Foundation.  Oracle designates this
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11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
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24 */
25
26package com.sun.xml.internal.ws.api.server;
27
28import com.sun.xml.internal.ws.api.config.management.Reconfigurable;
29import com.sun.xml.internal.ws.api.Component;
30import com.sun.xml.internal.ws.api.pipe.Codec;
31import com.sun.xml.internal.ws.api.message.Packet;
32import com.sun.xml.internal.ws.api.server.WSEndpoint.PipeHead;
33import com.sun.xml.internal.ws.util.Pool;
34
35/**
36 * Receives incoming messages from a transport (such as HTTP, JMS, etc)
37 * in a transport specific way, and delivers it to {@link WSEndpoint.PipeHead#process}.
38 *
39 * <p>
40 * Since this class mostly concerns itself with converting a
41 * transport-specific message representation to a {@link Packet},
42 * the name is the "adapter".
43 *
44 * <p>
45 * The purpose of this class is twofolds:
46 *
47 * <ol>
48 * <li>
49 * To hide the logic of converting a transport-specific connection
50 * to a {@link Packet} and do the other way around.
51 *
52 * <li>
53 * To manage thread-unsafe resources, such as {@link WSEndpoint.PipeHead},
54 * and {@link Codec}.
55 * </ol>
56 *
57 * <p>
58 * {@link Adapter}s are extended to work with each kind of transport,
59 * and therefore {@link Adapter} class itself is not all that
60 * useful by itself --- it merely provides a design template
61 * that can be followed.
62 *
63 * <p>
64 * For managing resources, an adapter uses an object called {@link Toolkit}
65 * (think of it as a tray full of tools that a dentist uses ---
66 * trays are identical, but each patient has to get one. You have
67 * a pool of them and you assign it to a patient.)
68 *
69 * {@link Adapter.Toolkit} can be extended by derived classes.
70 * That actual type is the {@code TK} type parameter this class takes.
71 *
72 * @author Kohsuke Kawaguchi
73 */
74public abstract class Adapter<TK extends Adapter.Toolkit>
75        implements Reconfigurable, Component {
76
77    protected final WSEndpoint<?> endpoint;
78
79    /**
80     * Object that groups all thread-unsafe resources.
81     */
82    public class Toolkit {
83        /**
84         * For encoding/decoding infoset to/from the byte stream.
85         */
86        public final Codec codec;
87        /**
88         * This object from {@link WSEndpoint} serves the request.
89         */
90        public final PipeHead head;
91
92        public Toolkit() {
93            this.codec = endpoint.createCodec();
94            this.head = endpoint.createPipeHead();
95        }
96    }
97
98    /**
99     * Pool of {@link Toolkit}s.
100     *
101     * Instances of this pool may be replaced at runtime. Therefore, when you take
102     * an object out of the pool, you must make sure that it is recycled by the
103     * same instance of the pool.
104     */
105    protected volatile Pool<TK> pool = new Pool<TK>() {
106        protected TK create() {
107            return createToolkit();
108        }
109    };
110
111    /**
112     * Creates an {@link Adapter} that delivers
113     * messages to the given endpoint.
114     */
115    protected Adapter(WSEndpoint endpoint) {
116        assert endpoint!=null;
117        this.endpoint = endpoint;
118        // Enables other components to reconfigure this adapter
119        endpoint.getComponents().add(getEndpointComponent());
120    }
121
122    protected Component getEndpointComponent() {
123        return new Component() {
124                        public <S> S getSPI(Class<S> spiType) {
125                        if (spiType.isAssignableFrom(Reconfigurable.class)) {
126                            return spiType.cast(Adapter.this);
127                        }
128                                return null;
129                        }
130        };
131    }
132
133    /**
134     * The pool instance needs to be recreated to prevent reuse of old Toolkit instances.
135     */
136    public void reconfigure() {
137        this.pool = new Pool<TK>() {
138            protected TK create() {
139                return createToolkit();
140            }
141        };
142    }
143
144    public <S> S getSPI(Class<S> spiType) {
145        if (spiType.isAssignableFrom(Reconfigurable.class)) {
146            return spiType.cast(this);
147        }
148        if (endpoint != null) {
149                return endpoint.getSPI(spiType);
150        }
151        return null;
152    }
153
154    /**
155     * Gets the endpoint that this {@link Adapter} is serving.
156     *
157     * @return
158     *      always non-null.
159     */
160    public WSEndpoint<?> getEndpoint() {
161        return endpoint;
162    }
163
164    /**
165     * Returns a reference to the pool of Toolkits for this adapter.
166     *
167     * The pool may be recreated during runtime reconfiguration and this method
168     * will then return a reference to a new instance. When you recycle a toolkit,
169     * you must make sure that you return it to the same pool instance that you
170     * took it from.
171     *
172     * @return
173     */
174    protected Pool<TK> getPool() {
175        return pool;
176    }
177
178    /**
179     * Creates a {@link Toolkit} instance.
180     *
181     * <p>
182     * If the derived class doesn't have to add any per-thread state
183     * to {@link Toolkit}, simply implement this as {@code new Toolkit()}.
184     */
185    protected abstract TK createToolkit();
186}
187