3.4. Data

While the rule flow is designed specifically to allow you to create process control flows, you also have to plan it from a data perspective. Throughout the execution of a process, data is retrieved, stored, passed on and used.

To store run-time data while a process is executing, use variables. A variable is defined by a name and a data type. This could be something very basic, such as Boolean, int, or String, or it could be any kind of Object sub-class.

Define variables inside a variable scope. The top-level scope is that for the process itself. Sub-scopes can be defined via a composite node. Variables that are defined in sub-scopes can only be accessed by nodes within that scope.

Whenever a variable is accessed, the process will search for the appropriate definitive variable scope.

You are allowed to nest variable scopes. A node will always search for a variable in its parent container. If the variable cannot be found, it will look in that one's parent container, and so on, until the process instance itself is reached. If the variable cannot be found, a read access yields null, and a write access produces an error message, with the process continuing its execution.

You can use variables in these ways:

Finally, every process and rule can access globals. These are globally-defined variables that are considered immutable with regard to rule evaluation and data in the knowledge session.

You can access the knowledge session via the actions in the knowledge context:

kcontext.getKnowledgeRuntime().insert( new Person(...) );

kcontext.getKnowledgeRuntime().insert( new Person(...) );