Application instance services
An application instance service, also referred to as an ASC service, encapsulates business logic and is the part of your application instance that does the actual calculation.
A service can either be part of the application instance or independent. The services that are
created when you define an application template automatically become ASC services.
You can also manually create a service and select the type as ASC.
Note: If an
ASC service
that is tied to an application instance is removed outside the process of unregistering an
application instance, the other services that are part of the application instance are stopped; and
the application instance moves into the Register Error
state.
Stateful versus stateless
ASC services
can have one of the following stateful types:
| Stateful type | Description |
|---|---|
| Stateful | An ASC service that typically stores data locally to a disk on the host that it runs on. IBM® Spectrum Conductor aims to keep the service running on that host, and optionally enables decommissioning of the service to properly handle the data for that service when it is removed. |
| Stateless | An ASC service that does not store data locally on the host that is runs on. A stateless service can be safely restarted on a different host if necessary. By default, all ASC services are stateless. |
Service profile
The service profile is a XML file that defines service behavior.
It provides the information IBM Spectrum Conductor needs to run EGO and ASC services that are managed by the EGO Service Controller.
Every service, whether it is installed by default (a system service) or added by an administrator, has a service profile. When you register a service, you are registering the service profile that contains the service definition. It is good practice to edit the service profile through the cluster management console.
The service profile enables you to configure such properties as:
- The maximum and minimum number of service instances required by the service.
- A service description, which describes how to start a service instance for this service.
- Any resources required to run the service instances for this service.
- Any dependencies this service has (such as another service being started).
Note: Do not change the XML file for any of the system services (those installed by default)
unless specifically told to do so. You may, however, need to change ports.