The LSPS Expression Language is a statically typed, functional language used in models of the Living Systems® Process Suite to compute and process values.

It is not a full-fledged programming language and it is not possible to define business models exclusively in the LSPS Expression Language; however the language supports your modeling efforts: you will typically define properties of GO-BPMN elements as expressions in the LSPS Expression Language.

For example, you design a BPMN process with a Log task (Log tasks log messages into the logs and possibly to the console). You define the log message as an expression that results in a String in the Log property:

"Process " + processID + " started."

This expression uses String literals "Process " and " started", and the variable processID. On runtime, the system fetches the value of processID and concatenates the strings. The resolved expression is then used as the log message. Note that the processID variable is not defined in the expression: the variable is a global variable, which is a model element that exists in a variable resource file (refer to Model Elements).