Section A.7. OCL Automation

A.7. OCL Automation

The real power of OCL comes from tools that can use the OCL constraints from your UML model to perform constraint checking for you. While at the moment there is wide variation in tool maturity and level of integration, the ultimate goal is to enhance integration of your UML model with the runtime behavior of your system. This has the benefit of allowing you to catch errors early and saving on debugging time.

Some UML tools focus on placing the OCL constraints from your diagrams into generated code so that the constraints can be checked at runtime (although at the moment, these may only be proposed or partial implementations). Example approaches include generating assert statements directly in your code to allow constraint checking, or embellishing your code with Java annotations or doc-style tags containing OCL constraints, which can then be used by standard OCL tools that can check constraints at runtime. For example, the open source UML tool ArgoUML inserts OCL constraints into generated Java code as doc-style tags. With doc or annotations in your code, you can take advantage of OCL tools (such as ocl4java or the Dresden OCL Toolkit) that perform code enhancement to provide you runtime feedback about constraint violations in your executed code.

Stay on the lookout for developments in this area; as MDA and Executable UML (introduced in Chapter 1) become increasingly central to UML, you can expect even more of these capabilities to be integrated with modeling tools.