orbd - The Object Request Broker Daemon (ORBD) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

orbd - The Object Request Broker Daemon

orbd is used to enable clients to transparently locate and invoke persistent objects on servers in the CORBA environment.

See also: Naming Service

SYNOPSIS

orbd <options>

DESCRIPTION

The Server Manager included with the orbd tool is used to enable clients to transparently locate and invoke persistent objects on servers in the CORBA environment. The persistent servers, while publishing the persistent object references in the Naming Service, include the port number of the ORBD in the object reference instead of the port number of the Server. The inclusion of an ORBD port number in the object reference for persistent object references has the following advantages:

The object reference in the Naming Service remains independent of the server life cycle. For example, the object reference could be published by the server in the Naming Service when it is first installed, and then, independent of how many times the server is started or shutdown, the ORBD will always return the correct object reference to the invoking client.

The client needs to lookup the object reference in the Naming Service only once, and can keep re-using this reference independent of the changes introduced due to server life cycle.

To access ORBD's Server Manager, the server must be started using servertool, which is a command-line interface for application programmers to register, unregister, startup, and shutdown a persistent server. For more information on the Server Manager, see the section in this document titled Server Manager.

When orbd starts up, it also starts a naming service. For more information on the naming service, link to Naming Service.

OPTIONS

Required Options

-ORBInitialPort nameserverport: Specifies the port on which the name server should be started. Once started, orbd will listen for incoming requests on this port. Note that when using Solaris software, you must become root to start a process on a port under 1024. For this reason, we recommend that you use a port number greater than or equal to 1024. (required)

OTHER OPTIONS

-port port: Specifies the activation port where ORBD should be started, and where ORBD will be accepting requests for persistent objects. The default value for this port is 1049. This port number is added to the port field of the persistent Interoperable Object References (IOR). (optional)

-defaultdb directory: Specifies the base where the ORBD persistent storage directory orb.db is created. If this option is not specified, the default value is "./orb.db". (optional)

-serverPollingTime milliseconds: Specifies how often ORBD checks for the health of persistent servers registered via servertool. The default value is 1,000 ms. The value specified for milliseconds must be a valid positive integer. (optional)

-serverStartupDelay milliseconds: Specifies how long ORBD waits before sending a location forward exception after a persistent server that is registered via servertool is restarted. The default value is 1,000 ms. The value specified for milliseconds must be a valid positive integer. (optional)

-Joption: Pass option to the Java virtual machine, where option is one of the options described on the reference page for the java application launcher. For example, -J-Xms48m sets the startup memory to 48 megabytes. It is a common convention for -J to pass options to the underlying virtual machine.

Starting and Stopping the Naming Service

A Naming Service is a CORBA service that allows CORBA objects to be named by means of binding a name to an object reference. The name binding may be stored in the naming service, and a client may supply the name to obtain the desired object reference.

Prior to running a client or a server, you will start ORBD. ORBD includes a persistent Naming Service and a transient Naming Service, both of which are an implementation of the COS Naming Service.

The Persistent Naming Service provides persistence for naming contexts. This means that this information is persistent across service shutdowns and startups, and is recoverable in the event of a service failure. If ORBD is restarted, the Persistent Naming Service will restore the naming context graph, so that the binding of all clients' and servers' names remains intact (persistent).

For backward compatibility, tnameserv, a Transient Naming Service shipped with older versions of the JDK, is also included in this release of J2SE. A transient naming service retains naming contexts as long as it is running. If there is a service interruption, the naming context graph is lost.

The -ORBInitialPort argument is a required command-line argument for orbd, and is used to set the port number on which the Naming Service will run. The following instructions assume you can use port 1050 for the Java IDL Object Request Broker Daemon. When using Solaris software, you must become root to start a process on a port under 1024. For this reason, we recommend that you use a port number greater than or equal to 1024. You can substitute a different port if necessary.

To start orbd from a UNIX command shell, enter:

  orbd -ORBInitialPort 1050&

From an MS-DOS system prompt (Windows), enter:

  start orbd -ORBInitialPort 1050

Now that ORBD is running, you can run your server and client applications. When running the client and server applications, they must be made aware of the port number (and machine name, if applicable) where the Naming Service is running. One way to do this is to add the following code to your application:

        Properties props = new Properties();
        props.put("org.omg.CORBA.ORBInitialPort", "1050");
        props.put("org.omg.CORBA.ORBInitialHost", "MyHost");
        ORB orb = ORB.init(args, props);

In this example, the Naming Service is running on port 1050 on host "MyHost". Another way is to specify the port number and/or machine name when running the server or client application from the command line. For example, you would start your "HelloApplication" with the following command line:

     java HelloApplication -ORBInitialPort 1050 -ORBInitialHost MyHost

To stop the naming service, use the relevant operating system command, such as pkill orbd on Solaris, or Ctrl+C in the DOS window in which orbd is running. Note that names registered with the naming service may disappear when the service is terminated if the naming service is transient. The Java IDL naming service will run until it is explicitly stopped.

For more information on the Naming Service included with ORBD, see Naming Service.

Server Manager

To access ORBD's Server Manager and run a persistent server, the server must be started using servertool, which is a command-line interface for application programmers to register, unregister, startup, and shutdown a persistent server. When a server is started using servertool, it must be started on the same host and port on which orbd is executing. If the server is run on a different port, the information stored in the database for local contexts will be invalid and the service will not work properly.

Server Manager: an Example

Using the sample tutorial for our demonstration, you would run the idlj compiler and javac compiler as shown in the tutorial. To run the Server Manager, follow these steps for running the application:

Start orbd.

To start orbd from a UNIX command shell, enter:

  orbd -ORBInitialPort 1050

From an MS-DOS system prompt (Windows), enter:

  start orbd -ORBInitialPort 1050

Note that 1050 is the port on which you want the name server to run. -ORBInitialPort is a required command-line argument. When using Solaris software, you must become root to start a process on a port under 1024. For this reason, we recommend that you use a port number greater than or equal to 1024.

Start the servertool:

To start the Hello server, enter:

  servertool -ORBInitialPort 1050

Make sure the name server (orbd) port is the same as in the previous step, for example, -ORBInitialPort 1050. The servertool must be started on the same port as the name server.

The servertool command line interface appears.

Start the Hello server from the servertool prompt:

  servertool  > register -server HelloServer -classpath . -applicationName
                HelloServerApName

The servertool registers the server, assigns it the name of "HelloServerApName", and displays its server id, along with a listing of all registered servers.

Run the client application from another terminal window or prompt:

  java HelloClient -ORBInitialPort 1050 -ORBInitialHost localhost

For this example, you can omit -ORBInitialHost localhost since the name server is running on the same host as the Hello client. If the name server is running on a different host, use -ORBInitialHost nameserverhost to specify the host on which the IDL name server is running.

Specify the name server (orbd) port as done in the previous step, for example, -ORBInitialPort 1050.

When you have finished experimenting with the Server Manager, be sure to shut down or kill the name server (orbd) and servertool.

To shut down orbd from a DOS prompt, select the window that is running the server and enter Ctrl+C to shut it down. To shut down orbdfrom a Unix shell, find the process, and kill it. The server will continue to wait for invocations until it is explicitly stopped.

To shut down the servertool, type quit and press the Enter key on the keyboard.