Services
The workbench defines a number of services that can be retrieved from the
org.eclipse.ui.services.IServiceLocator.
Services provide a way for components to retrieve information about the workbench
without always having to go to the global singleton: PlatformUI.getWorkbench().
For example:
IHandlerService handlerService = (IHandlerService) getSite()
.getService(IHandlerService.class);
Some services provide 2 optional abilities, which are usually specified in the
service interface javadoc:
- Services that support listeners can clean up the listeners automatically
when the component's
org.eclipse.ui.services.IServiceLocator
(used to get the service) is disposed.
- Services can provide more localized services depending on which component they
are requested from.
See
Associating a handler programmically with a command...
for an example of the activation localization provided by the
org.eclipse.ui.handlers.IHandlerService.
Services Provided by the Workbench
The services provided to by the workbench now includes some of the most
common services that an
org.eclipse.ui.IWorkbenchPart
would require. Support for service related optional abilities are specified in the service javadoc.
The availability of the service is at and below the level specified.
| Service |
Description |
Availability |
|
IBindingService
|
Provides services related to the binding architecture (e.g., keyboard
shortcuts) within the workbench. |
Globally |
|
ICommandService
|
Provides services related to the command architecture within the workbench. |
Globally |
|
ICommandImageService
|
Provides a look-up facility for images associated with commands. |
Globally |
|
IContextService
|
Provides services related to contexts in the Eclipse workbench, like context
activation and definitions. |
Globally |
|
IContributionService
|
Instances of this service are capable of providing standard mechanisms that
clients may use to order, display, and generally work with contributions to
the Workbench. |
Globally |
|
IEvaluationService
|
Evaluate a core expression against the workbench application context and
report updates using a Boolean property. Also provides the main source for
the workbench application context. |
Globally |
|
IFocusService
|
Tracks focusGained and focusLost events for a Control registered with this
service, and provides the control and its registered ID as variables to the
application evaluation context for evaluation by the various services. |
Globally |
|
IHandlerService
|
Provides services related to activating and deactivating handlers within the
workbench. |
Globally |
|
IMenuService
|
Provides services related to the menu architecture within the workbench. It
can be used to populate MenuManagers and ToolBarManagers by components. |
Globally |
|
IPageService
|
A page service tracks the page and perspective lifecycle events
within a workbench window. |
Workbench Window |
|
IPartService
|
A part service tracks the creation and activation of parts within a
workbench window. |
Workbench Window |
|
IProgressService
|
The progress service is the primary interface to the workbench progress support. |
Globally |
|
IWorkbenchSiteProgressService
|
The part progress service is an IProgressService that adds API for jobs
that change the state in a IWorkbenchPartSite while they are being run. |
Part Site |
|
ISaveablesLifecycleListener
|
Parts that implement
org.eclipse.ui.ISaveablesSource
should notify their
ISaveablesLifecycleListener, available as a service from their site, about
org.eclipse.ui.Saveable
objects that have been added to or removed from the
part. Implementations of ISaveablesSource that are
not parts should retrieve this service from the
org.eclipse.ui.IWorkbench
object. |
Globally |
|
ISelectionService
|
A selection service tracks the selection within an a workbench window. |
Workbench Window |
Contributing a Service
Plug-in developers providing a framework in eclipse may also want to provide a service.
This can be done using the
org.eclipse.ui.services
extension point. Define a service factory based on
org.eclipse.ui.services.AbstractServiceFactory
and then specify what services the factory can return.
A factory can create more than one type of service, but multiple factories cannot
contribute to the same service type.
<serviceFactory
factoryClass="org.eclipse.ui.examples.contributions.model.PersonServiceFactory">
<service
serviceClass="org.eclipse.ui.examples.contributions.model.IPersonService"/>
</serviceFactory>
The create method of the
org.eclipse.ui.services.AbstractServiceFactory
passes in 3 parameters:
Workbench services are organized so there is a global service providing the
needed functionality, and a chain of children services. The children services provide
the listener cleanup and any data needed to localize the service request.
A service
factory should return the global service when the parentLocator returns
null when asked for the serviceInterface. The global service
may be the implementation, or a proxy to a plugin provided manager or OSGi service.
Object parentService = parentLocator.getService(IPersonService.class);
if (parentService == null) {
return new PersonService(locator);
}
return new PersonServiceSlave(locator, (IPersonService) parentService);
// or ...
Object parentService = parentLocator.getService(IPersonService.class);
if (parentService == null) {
return Activator.getDefault().getPersonManager();
}
return new PersonServiceSlave(locator, (IPersonService) parentService);
//
// or as a front to an OSGi service.
Object parentService = parentLocator.getService(IPersonService.class);
if (parentService == null) {
PersonServiceProxy proxy = new PersonServiceProxy(locator,
Activator.getDefault().getBundle().getBundleContext(),
0);
proxy.findService();
return proxy;
}
PersonServiceProxy proxy = new PersonServiceProxy(locator,
Activator.getDefault().getBundle().getBundleContext(),
((PersonServiceProxy)parentService).getLevel()+1);
proxy.findService();
return proxy;
In the OSGi service snippet above, instead of having each child IPersonService know
its parent, each IPersonService talks directly to the OSGi service and uses
the parent to calculate its "level" which allows it to localize any functionality
it provides.
