ServiceContext.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
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package org.jboss.com.sun.corba.se.spi.servicecontext;

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

/**
 * 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>
 * <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()
    {
    }

    /**
     * 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 = new EncapsOutputStream((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() + " ]";
    }
}