Cloud CM-IPMP Anleitung zur Fehlerbehebung PDF herunterladen (Seite 18)

• Within the SLEE. For example:

– The SLEE emits events to communicate changes in the SLEE that may be of interest to applications running in the

SLEE.

– The Timer Facility emits an event when a timer expires.

– The SLEE emits an event when an administrator modiﬁes the provisioned data for an application.

• An application running in the SLEE – applications may use events to signal or invoke other applications in the SLEE.

Every event in the SLEE has an event type. The event type of an event determines how the event is routed to different application

components.

3.3 Event Driven Applications

An event driven application typically does not have an active thread of execution. Instead, event handler sub-routines are

invoked by an ‘event routing’ component in response to receipt of events. These event handler sub-routines deﬁne application

code that inspect the event and perform appropriate processing to handle the event.

The SLEE component model models the external interface of an event driven application as the set of events that the application

may receive from the SLEE and external resources. Each event type is handled by an event handler method of one of the

software components in the application. This enforces a well-deﬁned event interface. A SLEE application may interact with

the resource that emitted the event (or other resources), ﬁre new events or update the application state.

A SLEE implementation provides the event routing behaviour (as deﬁned by the SLEE speciﬁcation) that invokes the event

handler methods of application software components.

3.4 Components

The SLEE architecture deﬁnes how an application can be composed of components. These components are known as Service

Building Block (SBB) components. An example of an SBB is a call forwarding service.

Each SBB component identiﬁes the event types accepted by the component and deﬁnes event handler methods that contain

application code for processing events of these event types. An SBB component may additionally deﬁne an interface for

synchronous method invocations.

At run-time, the SLEE creates instances of these components to process events.

3.5 Provisioned Data

The SLEE speciﬁcation deﬁnes management interfaces and speciﬁes how applications running in the SLEE access provisioned

data. Typical provisioned data includes conﬁguration data or per-subscriber data. The SLEE speciﬁcation uses objects called

“Proﬁles” to store provisioned data.

3.6 Facilities

The SLEE speciﬁcation deﬁnes a number of Facilities that may be used by SBB components.

These Facilities are:

• Timer Facility.

• Trace Facility.

• Usage Facility.

• Alarm Facility.

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