17.4 Bridging to the Model Compiler

Model compilers make extensive use of implicit bridging. The model compiler itself provides the engine for executing the models. Each of the Executable UML elements we have defined in this book is bridged implicitly. For example, when we say:

select any shipment from instances of Shipment
    where selected.waitingToBePacked;
generate readyToPack() to shipment;

both the select statement and the generate statement bridge implicitly to the chosen implementation in the selected model compiler. The generate statement, for example, could be implemented as a function call to a class or by adding a signal message to a queue. We, the modelers, don't know which one, and we don't even need to say explicitly that someone has to take care of making this mapping.

Similarly, the model compiler, by dint of its decisions about data organization and access schemes, knows how to turn the select statement into a call to an encapsulating function or to a SQL query on a database.