Modeling with xtUML · Module 11 · Unit 1

Introduction to OAL

Object Action Language

xtUML supports modeling data, processing and control. Data and control are modeled with graphical diagrams such as component, class, and state machine diagrams. Processing is modeled with an action language called Object Action Language (OAL).

OAL is similar in many ways to target programming languages such as Java, C++, Python or VHDL. However, it attempts to be:

• simple
• abstract
• model-aware
• translatable

OAL is simpler than most programming languages. It is meant to be somewhat minimal in its notation, while being rich enough to model all necessary processing. Object Action Language is abstract and works at the level of detail of the model in which is operates. The instructions in the action language are aware of the model of which it is a part in both its syntax and its meaning. The names of model elements such as classes, attributes, events, messages, ports and parameters are parsed in the action language. Finally, the action language is target independent and can be translated into target-specific languages by a model compiler.

In this module we present a series of short videos that include examples of the various action language statements and their usage. These videos are meant to be self-contained references for each OAL statement and to collectively form a comprehensive tutorial. So, we recommend that while you are watching each segment that you frequently pause the video and repeat the steps in your own workspace using the xtUML Editor. The familiar GPS Watch example model is the context for each exercise.