org.wandora.modules

Class AbstractModule

java.lang.Object

org.wandora.modules.AbstractModule

All Implemented Interfaces:

Module

Direct Known Subclasses:

AbstractTemplate, Axis2Service, BasicUserAuthenticator, DatabaseUserStore, DBTesterModule, DefaultReplacementsModule, DiskCacheModule, EmailModule, FileUserStore, GenericContext, GenericDatabaseInterface, GetUserAuthenticator, JettyModule, LoggingModule, ModulesServlet._ServletModule, ModulesWandoraWebAppHandler._ServletModule, NetAuthenticatorModule, ScriptModule, SimpleTopicMapManager, StaticTemplateContextProvider, StaticUserStore, TemplateActionExceptionHandler, TemplateManager, UserStoreCopyTool, VelocityEngineModule, WandoraServletModule, WandoraTopicMapManager

public abstract class AbstractModule
extends java.lang.Object
implements Module

A basic implementation of the Module interface. Implements all the methods but doesn't do anything useful on its own. The base implementation holds the initialisation and running states and does the bare minimum in the init, getDependencies, start and stop methods. Typically you will want to override at least some of them to add your own logic but still call the base implementation too.

Author:

olli

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	autoStart
protected boolean	isInitialized
protected boolean	isRunning
protected org.apache.commons.logging.Log	logging A Log implementation that is set in the require Logging method.
protected LoggingModule	loggingModule A logging module that is set in the requireLogging method.
protected ModuleManager	moduleManager The module manager that handles this module.

Constructor Summary

Constructors

Constructor and Description
AbstractModule()

Method Summary

Modifier and Type	Method and Description
java.util.Collection<Module>	getDependencies(ModuleManager manager) Returns all the modules this module depends on.
void	init(ModuleManager manager, java.util.HashMap<java.lang.String,java.lang.Object> settings) Initialises the module.
boolean	isInitialized() Checks if the module is initialised.
boolean	isRunning() Checks if the module is running.
protected java.util.Collection<Module>	requireLogging(ModuleManager manager, java.util.Collection<Module> dependencies) A helper method that adds logging into dependencies.
void	start(ModuleManager manager) Starts the module.
void	stop(ModuleManager manager) Stops the module.
java.lang.String	toString() Makes a string representation of this module using ModuleManager.moduleToString.

Methods inherited from class java.lang.Object

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

Field Detail

isInitialized

protected boolean isInitialized

isRunning

protected boolean isRunning

autoStart

protected boolean autoStart

loggingModule

protected LoggingModule loggingModule

A logging module that is set in the requireLogging method. See its documentation for more details.

logging

protected org.apache.commons.logging.Log logging

A Log implementation that is set in the require Logging method. See its documentation for more details.

moduleManager

protected ModuleManager moduleManager

The module manager that handles this module. First set in the init method.

Constructor Detail

AbstractModule

public AbstractModule()

Method Detail

init

public void init(ModuleManager manager,
                 java.util.HashMap<java.lang.String,java.lang.Object> settings)
          throws ModuleException

Description copied from interface: Module

Initialises the module. After constructor, this is the first method called in the life cycle of a module. It should not perform anything time consuming or anything with notable outside side effects. It should only read the parameters and initialise the module so that it can later be started. Note that a module being initialised doesn't mean that it necessarily will ever be started.

A ModuleException may be thrown if something vital is missing from the parameters or they are not sensible. In some cases you may not want to throw an exception even if vital initialisation information is missing. If, for example, it is possible that the module is initialised in some other way between the init and the start method calls. A ModuleException may also be thrown at the start method if the module is still not initialised.

Specified by:

init in interface Module

Parameters:

manager - The module manager handling this module. You may keep a reference to it if needed.

Throws:

ModuleException

isInitialized

public boolean isInitialized()

Description copied from interface: Module

Checks if the module is initialised. Should return true if init has been called and it did not throw an exception.

Specified by:

isInitialized in interface Module

Returns:

isRunning

public boolean isRunning()

Description copied from interface: Module

Checks if the module is running. Should return true if start has been called and it did not throw an exception and stop has not been called yet.

Specified by:

isRunning in interface Module

Returns:

getDependencies

public java.util.Collection<Module> getDependencies(ModuleManager manager)
                                             throws ModuleException

Description copied from interface: Module

Returns all the modules this module depends on. This method will be called after init and the dependencies are allowed to depend on the parameters passed to init. The modules that this module depends on must be returned as a collection. In addition, if any required module is not present, a MissingDependencyException should be thrown. Typically you will use the requireModule and optionalModule methods of the manager to make sure that the modules exist and add them to the collection. requireModule will automatically throw the exception too if the module is not found whereas optionalModule does not.

Specified by:

getDependencies in interface Module

Parameters:

manager - The module manager handling this module.

Returns:

A collection of modules this module depends on.

Throws:

ModuleException

requireLogging

protected java.util.Collection<Module> requireLogging(ModuleManager manager,
                                                      java.util.Collection<Module> dependencies)
                                               throws ModuleException

A helper method that adds logging into dependencies. Typically you will call this in your overridden getDependencies method. After that you can use the logging facilities of the logging instance variable. AbstractModule does not automatically require logging, but it provides some functionality for the typical case where you do need logging.

Note that typically modules are not usable before they have been started, and the logging module may only have been started just before calling start of this module. As such, the module would be unusable before that, in particular in init and getDependencies methods. However, logging modules should be built in such a way that they are usable immediately after having been initialised. In other words, you can assume that you can use it as soon as you have a reference to it. You may also call requireLogging already in init method to have logging available there. You should still also add it to the dependencies later in getDependencies.

Parameters:

manager -

dependencies -

Returns:

Throws:

ModuleException

start

public void start(ModuleManager manager)
           throws ModuleException

Description copied from interface: Module

Starts the module. This will be called after init and getDependencies and signals that the module should now begin to perform whatever it was designed to do. This method call however should not block for long, so any time consuming tasks should be started in their own threads. You will typically get references to the required modules again in start using the findModule method of the manager and then store those references to instance variables for later use. You may throw a ModuleException if the module is not in a state where it can be started or it immediately becomes obvious that it cannot be started with the provided settings.

Specified by:

start in interface Module

Parameters:

manager - The module manager handling this module.

Throws:

ModuleException

stop

public void stop(ModuleManager manager)

Description copied from interface: Module

Stops the module. Should stop all threads used by the module, free any large data structures and perform other cleanup. It is possible that the module will be started again later with a start method call (and foregoing init and getDependencies calls). The module should be left in a state where this is possible.

Specified by:

stop in interface Module

Parameters:

manager - The module manager handling this module.

toString

public java.lang.String toString()

Makes a string representation of this module using ModuleManager.moduleToString.

Overrides:

toString in class java.lang.Object

Returns:

A string representation of this module.