Java example source code file (StreamRemoteCall.java)

This example Java source code file (StreamRemoteCall.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.

Learn more about this Java project at its project page.

Java - Java tags/keywords

connectionoutputstream, datainputstream, dgc, error, exception, ioexception, marshaloutputstream, objectoutput, return, rmi, stacktraceelement, streamremotecall, suppresswarnings, tcpendpoint, unmarshalexception

The StreamRemoteCall.java Java example source code

/*
 * Copyright (c) 1996, 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 sun.rmi.transport;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.StreamCorruptedException;
import java.rmi.RemoteException;
import java.rmi.MarshalException;
import java.rmi.UnmarshalException;
import java.rmi.server.ObjID;
import java.rmi.server.RemoteCall;
import sun.rmi.runtime.Log;
import sun.rmi.server.UnicastRef;
import sun.rmi.transport.tcp.TCPEndpoint;

/**
 * Stream-based implementation of the RemoteCall interface.
 *
 * @author Ann Wollrath
 */
@SuppressWarnings("deprecation")
public class StreamRemoteCall implements RemoteCall {
    private ConnectionInputStream in = null;
    private ConnectionOutputStream out = null;
    private Connection conn;
    private boolean resultStarted = false;
    private Exception serverException = null;

    public StreamRemoteCall(Connection c) {
        conn = c;
    }

    public StreamRemoteCall(Connection c, ObjID id, int op, long hash)
        throws RemoteException
    {
        try {
            conn = c;
            Transport.transportLog.log(Log.VERBOSE,
                "write remote call header...");

            // write out remote call header info...
            // call header, part 1 (read by Transport)
            conn.getOutputStream().write(TransportConstants.Call);
            getOutputStream();           // creates a MarshalOutputStream
            id.write(out);               // object id (target of call)
            // call header, part 2 (read by Dispatcher)
            out.writeInt(op);            // method number (operation index)
            out.writeLong(hash);         // stub/skeleton hash
        } catch (IOException e) {
            throw new MarshalException("Error marshaling call header", e);
        }
    }

    /**
     * Return the connection associated with this call.
     */
    public Connection getConnection() {
        return conn;
    }

    /**
     * Return the output stream the stub/skeleton should put arguments/results
     * into.
     */
    public ObjectOutput getOutputStream() throws IOException {
        return getOutputStream(false);
    }

    private ObjectOutput getOutputStream(boolean resultStream)
        throws IOException
    {
        if (out == null) {
            Transport.transportLog.log(Log.VERBOSE, "getting output stream");

            out = new ConnectionOutputStream(conn, resultStream);
        }
        return out;
    }

    /**
     * Release the outputStream  Currently, will not complain if the
     * output stream is released more than once.
     */
    public void releaseOutputStream() throws IOException {
        try {
            if (out != null) {
                try {
                    out.flush();
                } finally {
                    out.done();         // always start DGC ack timer
                }
            }
            conn.releaseOutputStream();
        } finally {
            out = null;
        }
    }

    /**
     * Get the InputStream the stub/skeleton should get results/arguments
     * from.
     */
    public ObjectInput getInputStream() throws IOException {
        if (in == null) {
            Transport.transportLog.log(Log.VERBOSE, "getting input stream");

            in = new ConnectionInputStream(conn.getInputStream());
        }
        return in;
    }

    /**
     * Release the input stream, this would allow some transports to release
     * the channel early.
     */
    public void releaseInputStream() throws IOException {
        /* WARNING: Currently, the UnicastRef.java invoke methods rely
         * upon this method not throwing an IOException.
         */

        try {
            if (in != null) {
                // execute MarshalInputStream "done" callbacks
                try {
                    in.done();
                } catch (RuntimeException e) {
                }

                // add saved references to DGC table
                in.registerRefs();

                /* WARNING: The connection being passed to done may have
                 * already been freed.
                 */
                in.done(conn);
            }
            conn.releaseInputStream();
        } finally {
            in = null;
        }
    }

    /**
     * Returns an output stream (may put out header information
     * relating to the success of the call).
     * @param success If true, indicates normal return, else indicates
     * exceptional return.
     * @exception StreamCorruptedException If result stream previously
     * acquired
     * @exception IOException For any other problem with I/O.
     */
    public ObjectOutput getResultStream(boolean success) throws IOException {
        /* make sure result code only marshaled once. */
        if (resultStarted)
            throw new StreamCorruptedException("result already in progress");
        else
            resultStarted = true;

        // write out return header
        // return header, part 1 (read by Transport)
        DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
        wr.writeByte(TransportConstants.Return);// transport op
        getOutputStream(true);  // creates a MarshalOutputStream
        // return header, part 2 (read by client-side RemoteCall)
        if (success)            //
            out.writeByte(TransportConstants.NormalReturn);
        else
            out.writeByte(TransportConstants.ExceptionalReturn);
        out.writeID();          // write id for gcAck
        return out;
    }

    /**
     * Do whatever it takes to execute the call.
     */
    @SuppressWarnings("fallthrough")
    public void executeCall() throws Exception {
        byte returnType;

        // read result header
        DGCAckHandler ackHandler = null;
        try {
            if (out != null) {
                ackHandler = out.getDGCAckHandler();
            }
            releaseOutputStream();
            DataInputStream rd = new DataInputStream(conn.getInputStream());
            byte op = rd.readByte();
            if (op != TransportConstants.Return) {
                if (Transport.transportLog.isLoggable(Log.BRIEF)) {
                    Transport.transportLog.log(Log.BRIEF,
                        "transport return code invalid: " + op);
                }
                throw new UnmarshalException("Transport return code invalid");
            }
            getInputStream();
            returnType = in.readByte();
            in.readID();        // id for DGC acknowledgement
        } catch (UnmarshalException e) {
            throw e;
        } catch (IOException e) {
            throw new UnmarshalException("Error unmarshaling return header",
                                         e);
        } finally {
            if (ackHandler != null) {
                ackHandler.release();
            }
        }

        // read return value
        switch (returnType) {
        case TransportConstants.NormalReturn:
            break;

        case TransportConstants.ExceptionalReturn:
            Object ex;
            try {
                ex = in.readObject();
            } catch (Exception e) {
                throw new UnmarshalException("Error unmarshaling return", e);
            }

            // An exception should have been received,
            // if so throw it, else flag error
            if (ex instanceof Exception) {
                exceptionReceivedFromServer((Exception) ex);
            } else {
                throw new UnmarshalException("Return type not Exception");
            }
            // Exception is thrown before fallthrough can occur
        default:
            if (Transport.transportLog.isLoggable(Log.BRIEF)) {
                Transport.transportLog.log(Log.BRIEF,
                    "return code invalid: " + returnType);
            }
            throw new UnmarshalException("Return code invalid");
        }
    }

    /**
     * Routine that causes the stack traces of remote exceptions to be
     * filled in with the current stack trace on the client.  Detail
     * exceptions are filled in iteratively.
     */
    protected void exceptionReceivedFromServer(Exception ex) throws Exception {
        serverException = ex;

        StackTraceElement[] serverTrace = ex.getStackTrace();
        StackTraceElement[] clientTrace = (new Throwable()).getStackTrace();
        StackTraceElement[] combinedTrace =
            new StackTraceElement[serverTrace.length + clientTrace.length];
        System.arraycopy(serverTrace, 0, combinedTrace, 0,
                         serverTrace.length);
        System.arraycopy(clientTrace, 0, combinedTrace, serverTrace.length,
                         clientTrace.length);
        ex.setStackTrace(combinedTrace);

        /*
         * Log the details of a server exception thrown as a result of a
         * remote method invocation.
         */
        if (UnicastRef.clientCallLog.isLoggable(Log.BRIEF)) {
            /* log call exception returned from server before it is rethrown */
            TCPEndpoint ep = (TCPEndpoint) conn.getChannel().getEndpoint();
            UnicastRef.clientCallLog.log(Log.BRIEF, "outbound call " +
                "received exception: [" + ep.getHost() + ":" +
                ep.getPort() + "] exception: ", ex);
        }

        throw ex;
    }

    /*
     * method to retrieve possible server side exceptions (which will
     * be throw from exceptionReceivedFromServer(...) )
     */
    public Exception getServerException() {
        return serverException;
    }

    public void done() throws IOException {
        /* WARNING: Currently, the UnicastRef.java invoke methods rely
         * upon this method not throwing an IOException.
         */

        releaseInputStream();
    }
}