A structured approach to software process modelling

Systematic formulation of software process models (SPM) is currently a challenging problem in software engineering. We present an approach to define such models that encourages: reuse of both elements and models; modularity and incrementality in model construction; simplicity and naturality of the resulting model; and a high degree of concurrence in their enaction. We focus on model definition, distinguishing as usual its static and dynamic parts. We define the static part by means of formally defined hierarchies introducing the categories of elements that take part in SPM definition. Such hierarchies may be constructed and enlarged according to the requirements of any specific SPM. We present as an example a hierarchy for component programming that takes into account non-functional aspects of software (efficiency, etc.). The dynamic part of the SPM is defined by means of precedence relationships between tasks that take part in the model. These precedence relationships are represented with precedence graphs. Development strategies are defined by encapsulating new precedence relationships in modules, that can be combined and reused.