001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * The contents of this file are subject to the terms of either the GNU
007: * General Public License Version 2 only ("GPL") or the Common Development
008: * and Distribution License("CDDL") (collectively, the "License"). You
009: * may not use this file except in compliance with the License. You can obtain
010: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
011: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
012: * language governing permissions and limitations under the License.
013: *
014: * When distributing the software, include this License Header Notice in each
015: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
016: * Sun designates this particular file as subject to the "Classpath" exception
017: * as provided by Sun in the GPL Version 2 section of the License file that
018: * accompanied this code. If applicable, add the following below the License
019: * Header, with the fields enclosed by brackets [] replaced by your own
020: * identifying information: "Portions Copyrighted [year]
021: * [name of copyright owner]"
022: *
023: * Contributor(s):
024: *
025: * If you wish your version of this file to be governed by only the CDDL or
026: * only the GPL Version 2, indicate your decision by adding "[Contributor]
027: * elects to include this software in this distribution under the [CDDL or GPL
028: * Version 2] license." If you don't indicate a single choice of license, a
029: * recipient has the option to distribute your version of this file under
030: * either the CDDL, the GPL Version 2 or to extend the choice of license to
031: * its licensees as provided above. However, if you add GPL Version 2 code
032: * and therefore, elected the GPL Version 2 license, then the option applies
033: * only if the new code is made subject to such option by the copyright
034: * holder.
035: */
036:
037: package com.sun.xml.ws.api.pipe;
038:
039: import java.security.AccessController;
040: import java.security.PrivilegedAction;
041:
042: /**
043: * Interception for {@link Fiber} context switch.
044: *
045: * <p>
046: * Even though pipeline runs asynchronously, sometimes it's desirable
047: * to bind some state to the current thread running a fiber. Such state
048: * may include security subject (in terms of {@link AccessController#doPrivileged}),
049: * or a transaction.
050: *
051: * <p>
052: * This mechanism makes it possible to do such things, by allowing
053: * some code to be executed before and after a thread executes a fiber.
054: *
055: * <p>
056: * The design also encapsulates the entire fiber execution in a single
057: * opaque method invocation {@link Work#execute}, allowing the use of
058: * <tt>finally</tt> block.
059: *
060: *
061: * @author Kohsuke Kawaguchi
062: */
063: public interface FiberContextSwitchInterceptor {
064: /**
065: * Allows the interception of the fiber execution.
066: *
067: * <p>
068: * This method needs to be implemented like this:
069: *
070: * <pre>
071: * <R,P> R execute( Fiber f, P p, Work<R,P> work ) {
072: * // do some preparation work
073: * ...
074: * try {
075: * // invoke
076: * return work.execute(p);
077: * } finally {
078: * // do some clean up work
079: * ...
080: * }
081: * }
082: * </pre>
083: *
084: * <p>
085: * While somewhat unintuitive,
086: * this interception mechanism enables the interceptor to wrap
087: * the whole fiber execution into a {@link AccessController#doPrivileged(PrivilegedAction)},
088: * for example.
089: *
090: * @param f
091: * {@link Fiber} to be executed.
092: * @param p
093: * The opaque parameter value for {@link Work}. Simply pass this value to
094: * {@link Work#execute(Object)}.
095: * @return
096: * The opaque return value from the the {@link Work}. Simply return
097: * the value from {@link Work#execute(Object)}.
098: */
099: <R, P> R execute(Fiber f, P p, Work<R, P> work);
100:
101: /**
102: * Abstraction of the execution that happens inside the interceptor.
103: */
104: interface Work<R, P> {
105: /**
106: * Have the current thread executes the current fiber,
107: * and returns when it stops doing so.
108: *
109: * <p>
110: * The parameter and the return value is controlled by the
111: * JAX-WS runtime, and interceptors should simply treat
112: * them as opaque values.
113: */
114: R execute(P param);
115: }
116: }
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