orb.java

gcc的组建

   *
   * By default the built-in fully functional ORB is returned. The ORB class
   * is found as described in the header of this class.
   *
   * @param applet the applet. The property org.omg.CORBA.ORBClass,
   * if present, defines the used ORB implementation class. If this
   * property is not present, the ORB class is found as described in the
   * class header.
   *
   * @param props the properties, may be <code>null</code>.
   *
   * @return a newly created functional derivative of this abstract class.
   */
  public static ORB init(Applet applet, Properties props)
  {
    String ocn = applet.getParameter(FUNCTIONAL_ORB);
    String lp = applet.getParameter(LISTENER_PORT);
    
    if (ocn==null && lp!=null)
      ocn = DEFAULT_FOCUSED_ORB;
    
    ORB orb = createORB(props, ocn);
    orb.set_parameters(applet, props);

    return orb;
  }

  /**
   * Creates the working instance of ORB for a standalone application.
   * 
   * By default the built-in fully functional ORB is returned. The ORB class is
   * found as described in the header of this class.
   * 
   * @param args the parameters, passed to the applications
   * <code>main(String[] args)</code> method, may be <code>null</code>. The
   * parameter -org.omg.CORBA.ORBClass <class name> if present, defines the used
   * ORB implementation class. If this property is not present, the ORB class is
   * found as described in the class header.
   * 
   * @param props application specific properties, may be <code>null</code>.
   * 
   * @return a newly created functional derivative of this abstract class.
   */
  public static ORB init(String[] args, Properties props)
  {
    String ocn = null;
    String lp = null;

    String orbKey = "-" + FUNCTIONAL_ORB;
    String lpKey = "-" + LISTENER_PORT;

    if (args != null)
      if (args.length >= 2)
        {
          for (int i = 0; i < args.length - 1; i++)
            {
              if (args[i].equals(orbKey))
                ocn = args[i + 1];
              if (args[i].equals(lpKey))
                lp = args[i + 1];
            }
        }

    if (lp != null && ocn == null)
      ocn = DEFAULT_FOCUSED_ORB;

    ORB orb = createORB(props, ocn);

    orb.set_parameters(args, props);
    return orb;
  }

  /**
   * List the initially available CORBA objects (services).
   * 
   * @return a list of services.
   * 
   * @see #resolve_initial_references(String)
   */
  public abstract String[] list_initial_services();

  /**
   * Find and return the easily accessible CORBA object, addressed
   * by name.  The returned object is typically casted to the more
   * specific reference using the <code>narrow(Object)</code> method
   * of its helper. The method resolves the following string values,
   * returning the working objects:
   * <table border="1"><tr><th>String</th><th>Object class</th>
   * <th>Object use</th></tr>
   *
   * <tr><td>NameService</td><td>{@link org.omg.CosNaming.NamingContextExt}</td>
   * <td>Finds (usually remote) object by its name.</td></tr>
   *
   * <tr><td>RootPOA</td><td>{@link org.omg.PortableServer.POA}</td>
   * <td>Holds the POA tree for this ORB, where since 1.4 all servants
   * should be connected.</td></tr>
   *
   * <tr><td>RootPOAManager</td><td>{@link org.omg.PortableServer.POAManager}
   * </td><td>Regulates (suspends/resumes) the root POA
   * activity</td></tr>
   *
   * <tr><td>POACurrent</td><td>{@link org.omg.PortableServer.Current}
   * </td><td>Informs the current thread about the Id and POA of the
   * object being currently served (the methods of
   * <code>Current</code> return different values for
   * different threads).
   * </td></tr>
   *
   * <tr><td>CodecFactory</td><td>{@link org.omg.IOP.Codec}</td>
   * <td>Encodes/decodes IDL data types into/from byte arrays.</td>
   * </tr>
   *
   * <tr><td>DynAnyFactory</td><td>{@link org.omg.DynamicAny.DynAnyFactory}</td>
   * <td>Creates DynAny's.</td>
   * </tr>
   *
   * <tr><td>PICurrent</td><td>{@link org.omg.PortableInterceptor.Current}</td>
   * <td>Contains multiple slots where an interceptor can rememeber the
   * request - specific values between subsequent
   * calls of the interceptor methods.</td>
   * </tr>
   *
   * </table>
   *
   * @param name the object name.
   * @return the object
   * @throws org.omg.CORBA.ORBPackage.InvalidName if the given name
   * is not associated with the known object.
   */
  public abstract Object resolve_initial_references(String name)
    throws org.omg.CORBA.ORBPackage.InvalidName;

  /**
   * Get the IOR reference string for the given object.
   * IOR can be compared with the Internet address for a web page,
   * it provides means to locate the CORBA service on the web.
   * IOR contains the host address, port number, the object identifier
   * (key) inside the server, the communication protocol version,
   * supported charsets and so on.
   *
   * @param forObject the CORBA object
   * @return the object IOR representation.
   * @see #string_to_object(String)
   */
  public abstract String object_to_string(Object forObject);

  /**
   * This should perform the implementation dependent unit of work in the
   * main thread.
   *
   * This method is part of the support for the distribute use of the
   * single execution thread.
   *
   * Same as in Suns releases at least till 1.4 inclusive,
   * the distribute use of the single thread is not implemented.
   * Use multiple threads, provided by jre.
   *
   * The method returns without action.
   */
  public void perform_work()
  {
  }

  /**
  * Checks if the ORB needs the main thread to perform some work.
  * The method should return true if the ORB needs the main thread,
  * and false if it does not.
  *
  * This method is part of the support for the distribute use of the
  * single execution thread.
  *
  * Same as in Suns releases at least till 1.4 inclusive,
  * the distributed use of the single thread is not implemented.
  * Use multiple threads, provided by jre.
  *
  * @return false, always.
  */
  public boolean work_pending()
  {
    return false;
  }

  /**
   * <p>Find and return the CORBA object, addressed by the given
   * string representation. The object can be (an usually is)
   * located on a remote computer, possibly running a different
   * (not necessary java) CORBA implementation. The returned
   * object is typically casted to the more specific reference
   * using the <code>narrow(Object)</code> method of its helper.
   * </p><p>
   * This function supports the following input formats:<br>
   * 1. IOR reference (<b>ior:</b>nnnnn ..), usually computer generated.<br> 
   * 2. <b>corbaloc:</b>[<b>iiop</b>][version.subversion<b>@</b>]<b>:</b>host[<b>:</b>port]<b>/</b><i>key</i>
   * defines similar information as IOR reference, but is more human readable.
   * This type of reference may also contain multiple addresses (see
   * OMG documentation for complete format).<br>
   * 3. <b>corbaloc:rir:/</b><i>name</i> defines internal reference on this
   * ORB that is resolved using {@link #resolve_initial_references}, passing 
   * the given <i>name</i> as parameter.<br>
   * 4. <b>corbaname:rir:#</b><i>name</i> states that the given <i>name</i>
   * must be resolved using the naming service, default for this ORB.<br>
   * 5. <b>corbaname:</b>[<b>iiop</b>][version.subversion<b>@</b>]<b>:</b>host[<b>:</b>port]<b>#</b><i>name</i>
   * states that the <i>name</i> must be resolved using the naming service
   * that runs on the given host at the given port. The ORB expects to find 
   * there the {@link org.omg.CosNaming.NamingContext} under the key 
   * "NameService.<br>
   * 7. file://[file name] Read the object definition string from the 
   * file system<br>
   * 8. http://[url] Read the object definition string from the provided
   * url.<br>
   * 9. ftp://[url] Read the object definition string from the provided
   * url.<br>
   * 
   * <p>The default port is always 2809. The default iiop version is 1.0
   * that now may not always be supported, so we would recommend to specify
   * the version explicitly.</p>
   * <p>
   * The examples of the corbaloc and corbaname addresses:<br>
   * corbaname:rir:#xobj - ask local naming service for "xobj".<br>
   * corbaname:rir:/NameService#xobj - same (long form).<br>
   * corbaname:iiop:1.2@localhost:900#xobj - same, assuming that the naming 
   * service runs at port 900 on the local host and supports iiop 1.2.<br>
   * corbaname:iiop:localhost#xobj - same, assuming that the naming 
   * service runs at port 2809 on the local host and supports iiop 1.0.<br>
   * corbaloc::gnu.xxx.yy/Prod/TradingService - the object exists on the
   * host gnu.xxx.yy, port 2809 having the key "Prod/TradingService". Its ORB 
   * supports iiop 1.0.<br>
   * corbaloc::gnu.xxx.yy/Prod/TradingService:801 - the object exists on the
   * host gnu.xxx.yy, port 801 having the key "Prod/TradingService". Its ORB 
   * supports iiop 1.0 (iiop keyword ommitted).<br>
   * corbaloc:iiop:[e-mail]/Prod/TradingService - the object exists on the
   * host gnu.xxx.yy, port 801 having the key "Prod/TradingService". Its ORB 
   * supports iiop 1.1.<br>
   * corbaloc:rir:/NameService - the default naming service.
   *
   * @param IOR the object IOR representation string.
   *
   * @return the found CORBA object.
   * 
   * @throws BAD_PARAM if the string being parsed is invalid.
   * @throws DATA_CONVERSION if the string being parsed contains unsupported
   * prefix or protocol.
   * 
   * @see #object_to_string(org.omg.CORBA.Object)
   */
  public abstract Object string_to_object(String IOR);

  /**
   * Start listening on the input socket. This method
   * blocks the current thread until {@link #shutdown(boolean)}
   * is called and shutdown process is completed.
   */
  public void run()
  {
  }

  /**
   * Shutdown the ORB server.
   *
   * @param wait_for_completion if true, the current thread is
   * suspended untile the shutdown process is complete.
   */
  public void shutdown(boolean wait_for_completion)
  {
  }

  /**
   * Destroy this server, releasing the occupied resources.
   * The default method returns without action.
   */
  public void destroy()
  {
  }

  /**
   * Set the ORB parameters. This method is normally called from
   * {@link #init(String[], Properties)}.
   *
   * @param para the parameters, that were passed as the parameters
   * to the  <code>main(String[] args)</code> method of the current standalone
   * application.
   *
   * @param props application specific properties that were passed
   * as a second parameter in {@link #init(String[], Properties)}).
   * Can be <code>null</code>.
   */
  protected abstract void set_parameters(String[] para, Properties props);

  /**
   * Set the ORB parameters. This method is normally called from
   * {@link #init(Applet, Properties)}.
   *
   * @param app the current applet.
   *
   * @param props application specific properties, passed as the second
   * parameter in {@link #init(Applet, Properties)}.
   * Can be <code>null</code>.
   */
  protected abstract void set_parameters(Applet app, Properties props);

  /**
   * Get the property with the given name, searching in the standard
   * places for the ORB properties.
   */
  private static String getCumulatedProperty(Properties props, String property)
  {
    String orb_cn = null;

    if (props != null)
      orb_cn = props.getProperty(property, null);

    if (orb_cn == null)
      orb_cn = System.getProperty(property, null);

    if (orb_cn == null)
      orb_cn = checkFile(property, "user.home", null);

    if (orb_cn == null)
      orb_cn = checkFile(property, "java.home", "lib");
    
    return orb_cn;
  }

  /**
   * Check if the property is defined in the existsting file orb.properties.
   *
   * @param property the property
   * @param dir the system property, defining the folder where the
   * file could be expected.
   * @param subdir subfolder where to look for the file.
   *
   * @return the property value, null if not found or file does not exist.
   */
  private static String checkFile(String property, String dir, String subdir)
  {
    try
      {
        File f = new File(dir);
        if (!f.exists())
          return null;

        if (subdir != null)
          f = new File(f, subdir);

        f = new File(f, "orb.properties");

        if (!f.exists())
          return null;

        Properties p = new Properties();
        p.load(new BufferedInputStream(new FileInputStream(f)));

        return p.getProperty(property, null);
      }
    catch (IOException ex)
      {
        return null;
      }
  }

  /**
   * Create ORB when its name is possibly known.
   * 
   * @param props properties, possibly containing the ORB name.
   * @param orbClassName the direct ORB class name, overriding other possible
   * locations, or null if not specified.
   */
  private static ORB createORB(Properties props, String orbClassName)
  {
    ORB orb = null;

    if (orbClassName == null)
      {
        orbClassName = getCumulatedProperty(props, FUNCTIONAL_ORB);

        if (orbClassName == null)
          {
            String lp = getCumulatedProperty(props, LISTENER_PORT);
            if (lp != null)
              orbClassName = DEFAULT_FOCUSED_ORB;
            else
              orbClassName = DEFAULT_FUNCTIONAL_ORB;
          }
      }

    try
      {
        orb = (ORB) ObjectCreator.forName(orbClassName).newInstance();
      }
    catch (ClassNotFoundException ex)
      {
        noORB(orbClassName, ex);
      }
    catch (IllegalAccessException ex)
      {
        noORB(orbClassName, ex);
      }
    catch (InstantiationException ex)
      {
        noORB(orbClassName, ex);
      }

    return orb;
  }

  /**
   * Throw the runtime exception.
   *
   * @param orb_c the ORB class name.
   * @param why the explaining chained exception.
   */
  private static void noORB(String orb_c, Throwable why)
  {
    throw new RuntimeException("The ORB " + orb_c + " cannot be instantiated.",
                               why
                              );
  }
}