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11 The Worklet Service 299
instantiation and operation of the service instance. Individual YAWL services use
these parameters to specify settings such as the location of services, enabling of the
Exception Service, enabling of persistence, location of the Worklet Repository, and
so on. Setting values for parameters can be done using any text editor.
This section discusses the various parameters that can or may be set to success-
fully deploy the Worklet Service.

11.5.1 Configuration: Service Side

The configuration file for the Worklet Service has parameters for specifying the
URL of the Engine’s Interface B, the location of the WorkletService and Exception-
Service classes (i.e., the relative location of those classes within the web archive),
the locations of the interface classes that send notifications from the engine to the
service, and mappings for resolving the URLs of the service’s jsps to the internal
location of the page being requested. All these parameters are set to their defaults
in the deployed web archive, which assumes that the Worklet Service is installed in
the same servlet container as the Engine, but of course these can be changed to their
appropriate values where the service is installed remotely to the engine.
The configuration file also has two parameters that must be set for each individual
installation (see Listing 11.2):
The Repository parameter, which maps the disk location of the Worklet Repos-
itory for that installation (the default location is within the servlet container’s
deployed applications folder, but it can be any valid location on the local
server), allowing the repository to be installed in an appropriate place of the
administrator’s choosing depending on local needs
The EnablePersistence parameter, which when set to true enables persistence of
instantiated service objects to a database so that items and cases currently being
handled by the service may be persisted across sessions, and to allow log records
to be written to a database table. If the parameter is set to false, service states are
not persisted, and log entries are instead written to a comma-delimited file in the
Worklet Repository.

11.5.2 Configuration: Engine Side

When the Worklet Service has been installed, it is automatically configured to
receive notifications from the engine for worklet-enabled tasks as part of the selec-
tion process, that is, there are no explicit configuration tasks necessary to enable the
Selection Service. For the Exception Service, there are two relevant parameters in
the engine’s configuration file; the first sets the URL of the Exception Service (set
by default to a location relative to the same server as the engine is installed on).