The SLEE specification presents the operational lifecycle of a SLEE service — illustrated, defined and summarised below.
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What are SLEE services?
Services are SLEE components that provide the application logic to act on input from resource adaptors. |
Service lifecycle states
| State | Definition |
|---|---|
INACTIVE |
The service has been installed successfully and is ready to be activated, but not yet running. The SLEE will not create SBB entities of the service’s root SBB, to process events. |
ACTIVE |
The service is running. The SLEE will create SBB entities, of the service’s root SBB, to process initial events. The SLEE will also deliver events to SBB entities of the service’s SBBs, as appropriate. |
STOPPING |
The service is deactivating. Existing SBB entities of the service continue running and may complete their processing. But the SLEE will not create new SBB entities of the service’s root SBB, for new activities. |
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When the SLEE can reclaim all of a service’s SBB entities, it transitions out of the STOPPING state and returns to the INACTIVE state. |
Independent operational states
As explained in About SLEE Operational States, each event-router node in a Rhino cluster maintains its own lifecycle state machine, independent of other nodes in the cluster. This is also true for each service: one service might be INACTIVE on one node in a cluster, ACTIVE on another, and STOPPING on a third. The operational state of a service on each cluster node also persists to the disk-based database.
A service will enter the INACTIVE state, after node bootup and initialisation completes, if the database’s persistent operational state information for that service is missing, or is set to INACTIVE or STOPPING.
And, like node operational states, you can change the operational state of a service at any time, as long as least one node in the cluster is available to perform the management operation (regardless of whether or not the node whose operational state being changed is a current cluster member). For example, you might activate a service on node 103 before node 103 is booted — then, when node 103 boots, and after it completes initialisation, that service will transition to the ACTIVE state.
Configuring services
An administrator can configure a service before deployment by modifying its service-jar.xml deployment descriptor (in its deployable unit).
This includes specifying:
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the address profile table to use when a subscribed address selects initial events for the service’s root SBB
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the default event-router priority for the SLEE to give to root SBB entities of the service when processing initial events.
Individual SBBs used in a service can also have configurable properties or environment entries.
Values for these environment entries are defined in the sbb-jar.xml deployment descriptor included in the SBB’s component jar.
Administrators can set or adjust the values for each environment entry before the SBB is installed in the SLEE.
The SLEE only reads the configurable properties defined for a service or SBB deployment descriptor at deployment time. If you need to change the value of any of these properties, you’ll need to:
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uninstall the related component (service or SBB whose properties you want to configure) from the SLEE
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change the properties
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reinstall the component
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uninstall and reinstall other components (as needed) to satisfy dependency requirements enforced by the SLEE.
