org.apache.oodt.commons

Class MultiServer

java.lang.Object

org.apache.oodt.commons.MultiServer

public class MultiServer
extends Object

The MultiServer runs multiple server objects in a single JVM. Instead of running a separate product server, profile server, query server, and so forth, in their own JVMs, which are extremely heavy-weight operating system processes, we can put them into one JVM which reduces the memory footprint on a single computer enormously.

Specifying the Configuration

The MultiServer configuration is an XML document. Here's a sample:

<multiserver
   xmlns="http://oodt.jpl.nasa.gov/edm-commons/xml/multiserver"
   id="My Multi Server">
   <server
     class="org.apache.oodt.commons.product.rmi.ProductServiceImpl"
     id="urn:eda:rmi:BioServer"
     bind="rebind" />
   <server
     class="org.apache.oodt.commons.product.rmi.ProductServiceImpl"
     id="urn:eda:rmi:SpaceServer"
     bind="1800000" />
   <server
     class="org.apache.oodt.commons.profile.rmi.ProfileServiceImpl"
     id="urn:eda:rmi:Resource"
     bind="bind" />
   <properties>
     <property name="urn:eda:rmi:BioServer.handlers">
       edrn.MedHandler,edrn.SpecimenHandler
     </property>
     <property name="urn:eda:rmi:SpaceServer.handlers">
       pds.PlanetoidHandler
     </property>
     <property name="org.apache.oodt.commons.profile.Handlers">
       com.sun.ResourceHandler
     </property>
   </properties>
 </multiserver>

This would start three servers (two products, one profile) with the various property settings indicated. The MultiServer expects the property org.apache.oodt.commons.MultiServer.config to identify the URL of the configuration. You can shorten that to MultiServer.config or multiserver.config or even just config, in that order. If none of those properties are specified then the MultiServer will expect the URL to be the first (and only) command line argument.

The id attribute on the multiserver element tells the name of the whole application; it's used to prefix log messages.

Server Specification

Each <server> entry names a server to start. The class attribute is the name of the RMI-compatible Java class that the server will run. (Note that currently only RMI servers are supported.) The id attribute tells the name the server should use to register with the naming context. And the bind attribute tells how the registration should proceed. It can take on the following values:

• true meaning the object will attempt a bind. If the ID is already bound in the context, the MultiServer fails.
• false meaning the object won't be bound.
• rebind meaning the object will rebind its ID in the context, overwriting any previous binding.
• number meaining the object will rebind its ID once at starup, and every number milliseconds thereafter. This is, in OODT's experience, the most useful option as it helps an entire dpeloyed network of servers self-heal after a naming context restart.

Propery Specification

For convenience, System Properties may be specified in the configirutaion as well. However, any properties already defined (such as using the -D command-line argument) get priority and their values won't be overridden. To specify properties, list any number of <property> elements under the <properties> element with a name attribute naming the System Property key and the text of the element naming its value. Note that the text will be unwrapped.

Version:

$Revision: 1.3 $

Author:

Kelly

Field Summary

Fields

Modifier and Type	Field and Description
static int	AUTO Indicates server will try periodic rebinding.
static int	BINDING Inidcates server will try a bind.
static int	NONBINDING Indicates server won't be bound.
static int	REBINDING Indicates server will try a rebind.

Constructor Summary

Constructors

Constructor and Description
MultiServer()

Method Summary

Modifier and Type	Method and Description
static void	main(String[] argv) Start the multi server.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BINDING

public static final int BINDING

Inidcates server will try a bind.

See Also:

Constant Field Values

NONBINDING

public static final int NONBINDING

Indicates server won't be bound.

See Also:

Constant Field Values

REBINDING

public static final int REBINDING

Indicates server will try a rebind.

See Also:

Constant Field Values

AUTO

public static final int AUTO

Indicates server will try periodic rebinding.

See Also:

Constant Field Values

Constructor Detail

MultiServer

public MultiServer()

Method Detail

main

public static void main(String[] argv)
                 throws Throwable

Start the multi server.

Parameters:

argv - Command-line arguments.

Throws:

Throwable - if an error occurs.