org.apache.turbine.services
Class BaseServiceBroker

java.lang.Object
  org.apache.turbine.services.BaseServiceBroker

All Implemented Interfaces:

ServiceBroker

Direct Known Subclasses:

TurbineServices

public abstract class BaseServiceBroker

extends java.lang.Object

implements ServiceBroker

A generic implementation of a ServiceBroker which provides:

• Maintaining service name to class name mapping, allowing plugable service implementations.
• Providing Services with a configuration based on system wide configuration mechanism.

Version:

$Id: BaseServiceBroker.java 264148 2005-08-29 14:21:04Z henning $

Author:

Kevin Burton, Rafal Krzewski, Daniel Rall, Jason van Zyl, Martin Poeschl, Henning P. Schmiedehausen

Field Summary

protected java.lang.String	applicationRoot Application root path as set by the parent application.
static java.lang.String	CLASSNAME_SUFFIX A Service property determining its implementing class name .
protected org.apache.commons.configuration.Configuration	configuration Configuration for the services broker.
protected org.apache.commons.configuration.Configuration	mapping Mapping of Service names to class names.
static java.lang.String	SERVICE_PREFIX A prefix for Service properties in TurbineResource.properties.
protected java.util.Hashtable	serviceObjects These are objects that the parent application can provide so that application specific services have a mechanism to retrieve specialized information.
protected java.util.Hashtable	services A repository of Service instances.

Constructor Summary

protected

BaseServiceBroker() Default constructor, protected as to only be useable by subclasses.

Method Summary

java.lang.String	getApplicationRoot() Get the application root as set by the parent application.
org.apache.commons.configuration.Configuration	getConfiguration() Get the configuration for this service manager.
org.apache.commons.configuration.Configuration	getConfiguration(java.lang.String name) Returns the configuration for the specified service.
Service	getService(java.lang.String name) Returns an instance of requested Service.
protected Service	getServiceInstance(java.lang.String name) Retrieves an instance of a Service without triggering late initialization.
java.util.Iterator	getServiceNames() Returns an Iterator over all known service names.
java.util.Iterator	getServiceNames(java.lang.String prefix) Returns an Iterator over all known service names beginning with the provided prefix.
java.lang.Object	getServiceObject(java.lang.String name) Get an application specific service object.
void	init() Initialize this service manager.
protected void	initMapping() Creates a mapping between Service names and class names.
void	initService(java.lang.String name) Performs early initialization of specified service.
void	initServices() Performs early initialization of all services.
void	initServices(boolean report) Performs early initialization of all services.
boolean	isRegistered(java.lang.String serviceName) Determines whether a service is registered in the configured TurbineResources.properties.
void	setApplicationRoot(java.lang.String applicationRoot) Set the application root.
void	setConfiguration(org.apache.commons.configuration.Configuration configuration) Set the configuration object for the services broker.
void	setServiceObject(java.lang.String name, java.lang.Object value) Set an application specific service object that can be used by application specific services.
void	shutdownService(java.lang.String name) Shuts down a Service, releasing resources allocated by an Service, and returns it to its initial (uninitialized) state.
void	shutdownServices() Shuts down all Turbine services, releasing allocated resources and returning them to their initial (uninitialized) state.

Methods inherited from class java.lang.Object

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

Field Detail

mapping

protected org.apache.commons.configuration.Configuration mapping

Mapping of Service names to class names.

services

protected java.util.Hashtable services

A repository of Service instances.

configuration

protected org.apache.commons.configuration.Configuration configuration

Configuration for the services broker. The configuration should be set by the application in which the services framework is running.

SERVICE_PREFIX

public static final java.lang.String SERVICE_PREFIX

A prefix for Service properties in TurbineResource.properties.

See Also:

Constant Field Values

CLASSNAME_SUFFIX

public static final java.lang.String CLASSNAME_SUFFIX

A Service property determining its implementing class name .

See Also:

Constant Field Values

serviceObjects

protected java.util.Hashtable serviceObjects

These are objects that the parent application can provide so that application specific services have a mechanism to retrieve specialized information. For example, in Turbine there are services that require the RunData object: these services can retrieve the RunData object that Turbine has placed in the service manager. This alleviates us of the requirement of having init(Object) all together.

applicationRoot

protected java.lang.String applicationRoot

Application root path as set by the parent application.

Constructor Detail

BaseServiceBroker

protected BaseServiceBroker()

Default constructor, protected as to only be useable by subclasses. This constructor does nothing.

Method Detail

setConfiguration

public void setConfiguration(org.apache.commons.configuration.Configuration configuration)

Set the configuration object for the services broker. This is the configuration that contains information about all services in the care of this service manager.

Parameters:

configuration - Broker configuration.

getConfiguration

public org.apache.commons.configuration.Configuration getConfiguration()

Get the configuration for this service manager.

Returns:

Broker configuration.

init

public void init()
          throws InitializationException

Initialize this service manager.

Throws:

InitializationException

setServiceObject

public void setServiceObject(java.lang.String name,
                             java.lang.Object value)

Set an application specific service object that can be used by application specific services.

Parameters:

name - name of service object

value - value of service object

getServiceObject

public java.lang.Object getServiceObject(java.lang.String name)

Get an application specific service object.

Returns:

Object application specific service object

initMapping

protected void initMapping()

Creates a mapping between Service names and class names. The mapping is built according to settings present in TurbineResources.properties. The entries should have the following form:

 services.MyService.classname=com.mycompany.MyServiceImpl
 services.MyOtherService.classname=com.mycompany.MyOtherServiceImpl
 

Generic ServiceBroker provides no Services.

isRegistered

public boolean isRegistered(java.lang.String serviceName)

Determines whether a service is registered in the configured TurbineResources.properties.

Specified by:

isRegistered in interface ServiceBroker

Parameters:

serviceName - The name of the service whose existance to check.

Returns:

Registration predicate for the desired services.

getServiceNames

public java.util.Iterator getServiceNames()

Returns an Iterator over all known service names.

Returns:

An Iterator of service names.

getServiceNames

public java.util.Iterator getServiceNames(java.lang.String prefix)

Returns an Iterator over all known service names beginning with the provided prefix.

Parameters:

prefix - The prefix against which to test.

Returns:

An Iterator of service names which match the prefix.

initService

public void initService(java.lang.String name)
                 throws InitializationException

Performs early initialization of specified service.

Specified by:

initService in interface ServiceBroker

Parameters:

name - The name of the service (generally the SERVICE_NAME constant of the service's interface definition).

Throws:

InitializationException - Initialization of this service was not successful.

initServices

public void initServices()

Performs early initialization of all services. Failed early initialization of a Service may be non-fatal to the system, thus any exceptions are logged and the initialization process continues.

initServices

public void initServices(boolean report)
                  throws InstantiationException,
                         InitializationException

Performs early initialization of all services. You can decide to handle failed initializations if you wish, but then after one service fails, the other will not have the chance to initialize.

Parameters:

report - true if you want exceptions thrown.

Throws:

InstantiationException

InitializationException

shutdownService

public void shutdownService(java.lang.String name)

Shuts down a Service, releasing resources allocated by an Service, and returns it to its initial (uninitialized) state.

Specified by:

shutdownService in interface ServiceBroker

Parameters:

name - The name of the Service to be uninitialized.

shutdownServices

public void shutdownServices()

Shuts down all Turbine services, releasing allocated resources and returning them to their initial (uninitialized) state.

Specified by:

shutdownServices in interface ServiceBroker

getService

public Service getService(java.lang.String name)
                   throws InstantiationException

Returns an instance of requested Service.

Specified by:

getService in interface ServiceBroker

Parameters:

name - The name of the Service requested.

Returns:

An instance of requested Service.

Throws:

InstantiationException - if the service is unknown or can't be initialized.

getServiceInstance

protected Service getServiceInstance(java.lang.String name)
                              throws InstantiationException

Retrieves an instance of a Service without triggering late initialization. Early initialization of a Service can require access to Service properties. The Service must have its name and serviceBroker set by then. Therefore, before calling Initable.initClass(Object), the class must be instantiated with InitableBroker.getInitableInstance(), and Service.setServiceBroker() and Service.setName() must be called. This calls for two - level accessing the Services instances.

Parameters:

name - The name of the service requested.

Throws:

InstantiationException - The service is unknown or can't be initialized.

getConfiguration

public org.apache.commons.configuration.Configuration getConfiguration(java.lang.String name)

Returns the configuration for the specified service.

Specified by:

getConfiguration in interface ServiceBroker

Parameters:

name - The name of the service.

Returns:

Configuration of requested Service.

setApplicationRoot

public void setApplicationRoot(java.lang.String applicationRoot)

Set the application root.

Parameters:

applicationRoot - application root

getApplicationRoot

public java.lang.String getApplicationRoot()

Get the application root as set by the parent application.

Returns:

String application root