wt.services.applicationcontext.implementation
Class WTServiceProvider

java.lang.Object
  wt.services.applicationcontext.implementation.WTServiceProvider

All Implemented Interfaces:

ApplicationContextServiceProvider, Serializable

Direct Known Subclasses:

WTServiceProviderFromProperties

public class WTServiceProvider

extends Object

implements ApplicationContextServiceProvider, Serializable

An implementation of ApplicationContextServiceProvider which keeps track of services by keeping a collection of WTServiceInfo objects. It does not know how these objects are derived. WTServiceInfo objects can be manufactured in code or read in from some sort of file.

At the abstraction level of package applicationcontext, the requestor is just an object instance. This means that in applicationcontext the getService operations use the requestor object but there is no assumption about how that object is used to locate the service. Class WTServiceProvider in implementation uses the object to come up with an ordered set of class names. These class names are searched for a matching service from the most concrete to the most abstract.

Supported API: false

Extendable: false

See Also:

Serialized Form

Field Summary

private static String	CLASSNAME
private static String	RESOURCE
private Hashtable	service
private com.objectspace.jgl.HashMap	serviceImplementationSingletons
private com.objectspace.jgl.HashMap	serviceInfos
private Hashtable	serviceInfosForRequestor
private com.objectspace.jgl.HashMap	serviceInfosWOSelector
private static boolean	VERBOSE

Fields inherited from interface wt.services.applicationcontext.ApplicationContextServiceProvider

SERVICE, WILD_CARD

Constructor Summary

WTServiceProvider()
An abstract implementation of ApplicationContextServiceProvider.

Method Summary

boolean	addServiceInfo(WTServiceInfo serviceInfo) Add an externally derived service information entry.
protected String	createInfoKey(String serviceName, String selector, String requestorName)
protected String	createInfoKeyWOSelector(String serviceName, String requestorName)
protected Vector	getAllClasses(Object object)
protected void	getAllSuperClasses(Class aClass, Vector allClasses)
Object	getService(ApplicationContextChild contextChild, Object requestor, Class serviceClass, Object selector) Get an array of services based on context, requestor, selector, and logical service name.
Object	getService(ApplicationContextChild contextChild, Object requestor, String serviceName, Object selector) Get an array of services based on context, requestor, selector, and logical service name.
protected Object	getServiceImplementation(ApplicationContextChild contextChild, Object requestor, String serviceName, String implementationName, boolean isSingleton)
String	getServiceImplementationName(ApplicationContextChild contextChild, Object requestor, String serviceName, Object selector) Get the name of the service implementation class for a particular context, requestor, selector, and logical service name.
Map	getServiceImplementationNameMap(ApplicationContextChild contextChild, ACRequestor requestor, String serviceName, Object selector) Return the name of the service implementation.
Map	getServiceImplementationNameMap(ApplicationContextChild contextChild, Object[] requestors, String serviceName, Object selector) Return the name of the service implementation.
WTServiceInfo[]	getServiceInfos() Return service info entries.
protected WTServiceInfo[]	getServiceInfosForRequestor(ApplicationContextChild contextChild, Object requestor, String serviceName, String selector)
protected com.objectspace.jgl.HashMap	getServiceInfosWOSelector() Gets the object for the association that plays role: serviceInfosWOSelector.
Map	getServiceMap(ApplicationContextChild contextChild, ACRequestor requestor, Class serviceClass, Object selector) Return a service based on context, requestor and logical service type.
Map	getServiceMap(ApplicationContextChild contextChild, ACRequestor requestor, String serviceName, Object selector) Return an instance of a service based on context, requestor and logical service name.
Map	getServiceMap(ApplicationContextChild contextChild, Object[] requestors, Class serviceClass, Object selector) Return a service based on context, requestor and logical service type.
Map	getServiceMap(ApplicationContextChild contextChild, Object[] requestors, String serviceName, Object selector) Return an instance of a service based on context, requestor and logical service name.
String[]	getServiceNames() Supported API: false
Enumeration	getServiceSelectors(ApplicationContextChild contextChild, String serviceName, Object requestor) Supported API: false
protected Object	getSingletonImplementation(Class implementationClass) If the implementation class doesn't have a public constructor, looks for a static getInstance() method to use to instantiate the service.
void	printOn(PrintStream ps)
protected void	setServiceInfosWOSelector(com.objectspace.jgl.HashMap a_ServiceInfosWOSelector) Sets the object for the association that plays role: serviceInfosWOSelector.

Methods inherited from class java.lang.Object

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

Field Detail

RESOURCE

private static final String RESOURCE

See Also:

Constant Field Values

CLASSNAME

private static final String CLASSNAME

serviceInfosWOSelector

private com.objectspace.jgl.HashMap serviceInfosWOSelector

serviceImplementationSingletons

private com.objectspace.jgl.HashMap serviceImplementationSingletons

serviceInfosForRequestor

private Hashtable serviceInfosForRequestor

serviceInfos

private com.objectspace.jgl.HashMap serviceInfos

service

private Hashtable service

VERBOSE

private static boolean VERBOSE

Constructor Detail

WTServiceProvider

public WTServiceProvider()

An abstract implementation of ApplicationContextServiceProvider. Class WTServiceProvider maintains a collection of WTServiceInfo objects. Each WTServiceInfo object represents one mapping from a logical service a requestor (class) name and an optional selector to the name of the class or resource which is appropriate.

Supported API: false

Method Detail

getServiceInfosWOSelector

protected com.objectspace.jgl.HashMap getServiceInfosWOSelector()

Gets the object for the association that plays role: serviceInfosWOSelector.

Supported API: false

Returns:

HashMap

setServiceInfosWOSelector

protected void setServiceInfosWOSelector(com.objectspace.jgl.HashMap a_ServiceInfosWOSelector)

Sets the object for the association that plays role: serviceInfosWOSelector.

Supported API: false

Parameters:

a_ServiceInfosWOSelector -

getServiceNames

public String[] getServiceNames()

Supported API: false

Specified by:

getServiceNames in interface ApplicationContextServiceProvider

Returns:

String[]

getService

public Object getService(ApplicationContextChild contextChild,
                         Object requestor,
                         String serviceName,
                         Object selector)
                  throws ServiceNotFoundException,
                         UnableToCreateServiceException

Get an array of services based on context, requestor, selector, and logical service name.

Prior to R3.0 this method was implemented to return only a single service, not an array of services.

The algorithm for resolving a service was as follows:

• If there is more than one WTServiceInfo for a logical service with the same context and selector, then select one of them based on the proximity of the requestor to the requestor's of all matching WTServiceInfos as follows:
  • If all priorities are equal, get the service implementation which is the closest parent to the requestor based on class hierarchy.
  • If there are different priorities, get the service implementation which has the highest priority and is the closest parent to the requestor based on class hierarchy.

For R3.0 the algortihm has been modified to return multiple service implementation based on the following rules:

• If there is more than one WTServiceInfo for a logical service with the same context and selector than select one of them based on the proximity of the requestor to the requestor's of all matching WTServiceInfos as follows:
  • Get all service implementations with the highest priority.
  • Return the service implementations in an order so that the first element is the closest parent and the last element is the most distant parent with respect to the requestor.

ApplicationContextServicesSupport implements its getService method to return the first element in the array of service implemenations returned by this method. This maintains backward compatibility with the R2.X implementation of this method.

ApplicationContextServicesSupport implements a new method, getServices, which returns all the service implementations resolved through the above rules.

Supported API: false

Specified by:

getService in interface ApplicationContextServiceProvider

Parameters:

contextChild - The context in which the service is being requested. May be null.

requestor - The target of the service request.

serviceName - The name of the logical service.

selector -

Returns:

Object

Throws:

ServiceNotFoundException

UnableToCreateServiceException

getService

public Object getService(ApplicationContextChild contextChild,
                         Object requestor,
                         Class serviceClass,
                         Object selector)
                  throws ServiceNotFoundException,
                         UnableToCreateServiceException

Get an array of services based on context, requestor, selector, and logical service name. See the javadoc for the other variation of getService in this class.

Supported API: false

Specified by:

getService in interface ApplicationContextServiceProvider

Parameters:

contextChild - The context in which the service is being requested.

requestor - The object on who's behalf the service is being requested.

serviceClass - The logical service class.

selector -

Returns:

Object

Throws:

ServiceNotFoundException

UnableToCreateServiceException

getServiceMap

public Map getServiceMap(ApplicationContextChild contextChild,
                         Object[] requestors,
                         String serviceName,
                         Object selector)
                  throws UnableToCreateServiceException

Return an instance of a service based on context, requestor and logical service name.

Supported API: false

Specified by:

getServiceMap in interface ApplicationContextServiceProvider

Parameters:

contextChild - The context in which the service is being requested.

requestors - The target of the service request.

serviceName - The name of the requested service.

selector - An optional selector to further identify the service.

Returns:

Map

Throws:

UnableToCreateServiceException

getServiceMap

public Map getServiceMap(ApplicationContextChild contextChild,
                         Object[] requestors,
                         Class serviceClass,
                         Object selector)
                  throws UnableToCreateServiceException

Return a service based on context, requestor and logical service type.

Supported API: false

Specified by:

getServiceMap in interface ApplicationContextServiceProvider

Parameters:

contextChild - The service context in which the getService request was initiated.

requestors - The object on who's behalf the service request is being made.

serviceClass - The logical service class being requested.

selector - An optional selector to further identify the service.

Returns:

Map

Throws:

UnableToCreateServiceException

getServiceMap

public Map getServiceMap(ApplicationContextChild contextChild,
                         ACRequestor requestor,
                         String serviceName,
                         Object selector)
                  throws UnableToCreateServiceException

Return an instance of a service based on context, requestor and logical service name.

Supported API: false

Specified by:

getServiceMap in interface ApplicationContextServiceProvider

Parameters:

contextChild - The context in which the service is being requested.

requestor -

serviceName - The name of the requested service.

selector - An optional selector to further identify the service.

Returns:

Map

Throws:

UnableToCreateServiceException

getServiceMap

public Map getServiceMap(ApplicationContextChild contextChild,
                         ACRequestor requestor,
                         Class serviceClass,
                         Object selector)
                  throws UnableToCreateServiceException

Return a service based on context, requestor and logical service type.

Supported API: false

Specified by:

getServiceMap in interface ApplicationContextServiceProvider

Parameters:

contextChild - The service context in which the getService request was initiated.

requestor -

serviceClass - The logical service class being requested.

selector - An optional selector to further identify the service.

Returns:

Map

Throws:

UnableToCreateServiceException

getServiceSelectors

public Enumeration getServiceSelectors(ApplicationContextChild contextChild,
                                       String serviceName,
                                       Object requestor)

Supported API: false

Specified by:

getServiceSelectors in interface ApplicationContextServiceProvider

Parameters:

contextChild -

serviceName -

requestor -

Returns:

Enumeration

getServiceImplementationName

public String getServiceImplementationName(ApplicationContextChild contextChild,
                                           Object requestor,
                                           String serviceName,
                                           Object selector)

Get the name of the service implementation class for a particular context, requestor, selector, and logical service name. See javadoc for getService to understand how a service implementation class is resolved.

Supported API: false

Specified by:

getServiceImplementationName in interface ApplicationContextServiceProvider

Parameters:

contextChild -

requestor -

serviceName -

selector -

Returns:

String

getServiceImplementationNameMap

public Map getServiceImplementationNameMap(ApplicationContextChild contextChild,
                                           Object[] requestors,
                                           String serviceName,
                                           Object selector)

Return the name of the service implementation. Usuall this is the fully qualified class name, but it may be any string (implying that a service can't be instantiated.

Supported API: false

Specified by:

getServiceImplementationNameMap in interface ApplicationContextServiceProvider

Parameters:

contextChild - The context in which the service request was initiated. May be used to determine which service implementation should be returned.

requestors - The requestor or target of the service. Used to determine which service implementation should be returned.

serviceName - The logical name of the desired service.

selector - An optional selector to further identify the service.

Returns:

Map

getServiceImplementationNameMap

public Map getServiceImplementationNameMap(ApplicationContextChild contextChild,
                                           ACRequestor requestor,
                                           String serviceName,
                                           Object selector)

Return the name of the service implementation. Usuall this is the fully qualified class name, but it may be any string (implying that a service can't be instantiated.

Supported API: false

Specified by:

getServiceImplementationNameMap in interface ApplicationContextServiceProvider

Parameters:

contextChild - The context in which the service request was initiated. May be used to determine which service implementation should be returned.

requestor -

serviceName - The logical name of the desired service.

selector - An optional selector to further identify the service.

Returns:

Map

addServiceInfo

public boolean addServiceInfo(WTServiceInfo serviceInfo)

Add an externally derived service information entry.

Supported API: false

Parameters:

serviceInfo - The service info to be added.

Returns:

boolean

getServiceInfos

public WTServiceInfo[] getServiceInfos()

Return service info entries.

Supported API: false

Returns:

WTServiceInfo[]

getServiceImplementation

protected Object getServiceImplementation(ApplicationContextChild contextChild,
                                          Object requestor,
                                          String serviceName,
                                          String implementationName,
                                          boolean isSingleton)
                                   throws UnableToCreateServiceException

Throws:

UnableToCreateServiceException

getServiceInfosForRequestor

protected WTServiceInfo[] getServiceInfosForRequestor(ApplicationContextChild contextChild,
                                                      Object requestor,
                                                      String serviceName,
                                                      String selector)

getAllClasses

protected Vector getAllClasses(Object object)

getAllSuperClasses

protected void getAllSuperClasses(Class aClass,
                                  Vector allClasses)

createInfoKeyWOSelector

protected String createInfoKeyWOSelector(String serviceName,
                                         String requestorName)

createInfoKey

protected String createInfoKey(String serviceName,
                               String selector,
                               String requestorName)

printOn

public void printOn(PrintStream ps)

getSingletonImplementation

protected Object getSingletonImplementation(Class implementationClass)
                                     throws ClassNotFoundException,
                                            IllegalAccessException,
                                            InstantiationException

If the implementation class doesn't have a public constructor, looks for a static getInstance() method to use to instantiate the service.

Throws:

ClassNotFoundException

IllegalAccessException

InstantiationException