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Java example source code file (ServiceContext.java)

This example Java source code file (ServiceContext.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

corba, encapsoutputstream, giopversion, inputstream, servicecontext, string, systemexception

The ServiceContext.java Java example source code

/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.corba.se.spi.servicecontext;

import org.omg.CORBA.SystemException;
import org.omg.CORBA.INTERNAL;
import org.omg.CORBA_2_3.portable.InputStream ;
import org.omg.CORBA_2_3.portable.OutputStream ;
import com.sun.corba.se.spi.ior.iiop.GIOPVersion;
import com.sun.corba.se.spi.orb.ORB ;
import com.sun.corba.se.impl.encoding.CDRInputStream ;
import com.sun.corba.se.impl.encoding.EncapsInputStream ;
import com.sun.corba.se.impl.encoding.EncapsOutputStream ;
import com.sun.corba.se.impl.orbutil.ORBUtility ;

/** Base class for all ServiceContext classes.
* There is a derived ServiceContext class for each service context that
* the ORB supports.  Each subclass encapsulates the representation of
* the service context and provides any needed methods for manipulating
* the service context.  Each subclass must provide the following
* members:
* <p>
* <ul>
* </li>a public static final int SERVICE_CONTEXT_ID that gives the OMG
* (or other) defined id for the service context.  This is needed for the
* registration mechanism defined in ServiceContexts. OMG defined
* service context ids are taken from section 13.6.7 of ptc/98-12-04.</li>
* <li>a public constructor that takes an InputStream as its argument.
* <li>Appropriate definitions of getId() and writeData().  getId() must
* return SERVICE_CONTEXT_ID.</li>
* </ul>
* <p>
* The subclass can be constructed either directly from the service context
* representation, or by reading the representation from an input stream.
* These cases are needed when the service context is created and written to
* the request or reply, and when the service context is read from the
* received request or reply.
*/
public abstract class ServiceContext {
    /** Simple default constructor used when subclass is constructed
     * from its representation.
     */
    protected ServiceContext() { }

    private void dprint( String msg )
    {
        ORBUtility.dprint( this, msg ) ;
    }

    /** Stream constructor used when subclass is constructed from an
     * InputStream.  This constructor must be called by super( stream )
     * in the subclass.  After this constructor completes, the service
     * context representation can be read from in.
     * Note that the service context id has been consumed from the input
     * stream before this object is constructed.
     */
    protected ServiceContext(InputStream s, GIOPVersion gv) throws SystemException
    {
        in = s;
    }

    /** Returns Service context id.  Must be overloaded in subclass.
     */
    public abstract int getId() ;

    /** Write the service context to an output stream.  This method
     * must be used for writing the service context to a request or reply
     * header.
     */
    public void write(OutputStream s, GIOPVersion gv) throws SystemException
    {
        EncapsOutputStream os =
            sun.corba.OutputStreamFactory.newEncapsOutputStream((ORB)(s.orb()), gv);
        os.putEndian() ;
        writeData( os ) ;
        byte[] data = os.toByteArray() ;

        s.write_long(getId());
        s.write_long(data.length);
        s.write_octet_array(data, 0, data.length);
    }

    /** Writes the data used to represent the subclasses service context
     * into an encapsulation stream.  Must be overloaded in subclass.
     */
    protected abstract void writeData( OutputStream os ) ;

    /** in is the stream containing the service context representation.
     * It is constructed by the stream constructor, and available for use
     * in the subclass stream constructor.
     */
    protected InputStream in = null ;

    public String toString()
    {
        return "ServiceContext[ id=" + getId() + " ]" ;
    }
}

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