Administrator API
The administrator API also uses the RuleServiceProvider Class to
acquire an instance of the RuleAdministrator interface. The
RuleAdministrator interface provides methods to register and
de-register execution sets. The RuleAdministrator provides a
remote and local RuleExecutionSetProvider. As mentioned before
the RuleExecutionSetProvider is responsible for creating the
RuleExecutionSets. The RuleExecutionSets can be created from a
number of sources like XML streams, input streams etc. These
sources and their contents can be marshaled and serialized
across to a remote server where the rule engine is running. The
scenario of a remote rule engine or remote sources could be rare
in most applications. So to avoid the network overhead in these
cases the API provides for a Local RuleExecutionSetProvider,
which can read from sources running in the same JVM. The API
does not mandate the local RuleExecutionSetProvider but vendors
who do not implement the local RuleExecutionSetProvider will
have to return null.
The RuleExecutionSet interface has methods to get the metadata
about the RuleExecutionSet. It also has methods to retrieve all
the rule objects defined within the RuleExecutionSet. This
allows the client to know about the rule objects present in the
RuleExecutionSet and use them as they need.
Security
The Rules engine API separates the administration and the
runtime APIs so that fine grained security control can be
provided for these packages. The Rules engine API does not
provide any explicit security mechanism. The API is open enough
to be plugged with the standard security API defined in the J2EE
specification. Security can be provided with the Java
authentication and authorization service (JAAS), the Java
cryptography extension (JCE), Java secure Socket Extension
(JSSE) or any custom made security API. JAAS can be used to
define permissions to the RuleExecutionSets so that only
authorized users are allowed to access them.
Exceptions and Logging
The Rules Engine API defines a javax.rules.RuleException as the
root of the rules engine exception hierarchy. All other
exceptions will extend from this root class. The exceptions
defined in the rules engine are all checked exceptions, so the
responsibility of catching the exception falls on the
implementer.
The Rules Engine API does not provide an explicit logging
mechanism, but it suggests that the Java Logging API be used
with the Rules engine API.
Reference Implementation
In line with the recommendations of the Java Community Process,
the Java rules Engine Specification provides a reference
implementation. Unlike other reference implementations provided
with other specifications, which are free, the Java Rule Engine
reference implementation is not a full and free implementation.
The rules engine specification uses the JESS rule engine and
provides a wrapper around it. JESS is not freeware; so the
license of the RI is governed under the JESS license agreement.
However an academic license for JESS is offered at no cost.
Information and licensing information about JESS can be found in
the resources below.
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