fedora.server
Class Module

java.lang.Object
  fedora.server.Parameterized
      fedora.server.Pluggable
          fedora.server.Module

All Implemented Interfaces:

Constants

Direct Known Subclasses:

BasicPIDGenerator, ConnectionPoolManagerImpl, DefaultAccess, DefaultAuthorization, DefaultBackendSecurity, DefaultDOManager, DefaultDOReplicator, DefaultExternalContentManager, DefaultLowlevelStorageModule, DefaultManagement, DOTranslatorModule, DOValidatorModule, DynamicAccessModule, FedoraOAIProviderModule, FieldSearchSQLModule, Journaller, ResourceIndexModule, ThreadMonitorModule

public abstract class Module
extends Pluggable

Base class for Fedora server modules.

A Module is a singleton object of a Fedora Server instance with a simple lifecycle, supported by the initModule() and shutdownModule() methods, which are automatically called during server startup and shutdown, respectively.

Modules are configured via "param" elements inside module elements in the configuration file. An instance of each module specified in the configuration file is automatically created at startup and is available via the getModule(String) instance method of the Server class.

Version:

$Id: Module.java 5220 2006-11-20 13:52:20Z cwilper $

Author:

cwilper@cs.cornell.edu

Nested Class Summary

Nested classes/interfaces inherited from interface fedora.common.Constants

Constants.FedoraHome

Field Summary

Fields inherited from interface fedora.common.Constants

ACTION, BDEF, BMECH, DATASTREAM, DC, DISSEMINATOR, ENVIRONMENT, FEDORA, FEDORA_HOME, FEDORA_SYSTEM_DEF_PID, FEDORA_SYSTEM_DEF_URI, HTTP_REQUEST, MODEL, OBJECT, RDF, RECOVERY, RELS_EXT, RESOURCE, SUBJECT, TUCANA, VIEW, XSD

Constructor Summary

Module(java.util.Map moduleParameters, Server server, java.lang.String role)
Creates and initializes the Module.

Method Summary

java.lang.String	getRole() Gets the role this module fulfills, as given in the constructor.
Server	getServer() Gets the Server instance to which this Module belongs.
void	initModule() Initializes the Module based on configuration parameters.
void	postInitModule() Second stage of Module initialization.
void	shutdownModule() Frees system resources allocated by this Module.

Methods inherited from class fedora.server.Pluggable

getHelp, getOptionalParameters, getParameterHelp, getRequiredModuleRoles, getRequiredParameters

Methods inherited from class fedora.server.Parameterized

getParameter, getParameter, getParameters, parameterNames, setParameter, setParameters

Methods inherited from class java.lang.Object

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

Constructor Detail

Module

public Module(java.util.Map moduleParameters,
              Server server,
              java.lang.String role)
       throws ModuleInitializationException

Creates and initializes the Module.

When the server is starting up, this is invoked as part of the initialization process.

Parameters:

moduleParameters - A pre-loaded Map of name-value pairs comprising the intended configuration of this Module.

server - The Server instance.

role - The role this module fulfills, a java class name.

Throws:

ModuleInitializationException - If initilization values are invalid or initialization fails for some other reason.

Method Detail

getServer

public Server getServer()

Gets the Server instance to which this Module belongs.

Returns:

The Server instance.

getRole

public final java.lang.String getRole()

Gets the role this module fulfills, as given in the constructor.

Role is the name of the class or interface that this concrete Module extends or implements.

Returns:

String The role.

initModule

public void initModule()
                throws ModuleInitializationException

Initializes the Module based on configuration parameters.

Throws:

ModuleInitializationException - If initialization values are invalid or initialization fails for some other reason.

postInitModule

public void postInitModule()
                    throws ModuleInitializationException

Second stage of Module initialization. This is guaranteed to run after all Module's initModule() methods have run.

Throws:

ModuleInitializationException - If initialization values are invalid or initialization fails for some other reason.

shutdownModule

public void shutdownModule()
                    throws ModuleShutdownException

Frees system resources allocated by this Module.

Throws:

ModuleShutdownException - If there is a problem freeing system resources. Note that if there is a problem, it won't end up aborting the shutdown process. Therefore, this method should do everything possible to recover from exceptional situations before throwing an exception.