Executable Specification

Today the topic is executable specification.

To begin with, I would like to talk about eXecutable and Translatable UML diagram. According to the concept (Raistrick, 2009) : xtUML = UML - Semantic weak elements + Precisely defined action language. This helps to ensure that every unit of xtUML is clear and easy to understand, also we can translate it into code by some rules.

xtUML illustrates the relationships of subject, class and state. To be more specific a class model is created for each subject matter, while each state model can be only created for active class.

From this picture, it can be seen clearly that xtUML includes class model, state model, and because the rules of drawing these diagrams has some changes and class should be active, xtUML is actually a higher level of developing tools. Here, there is one thing needs to remember, objects communicates with each other by sending signal, and only active class could generate the signal.    

In this case , there comes to a new problem about xtUML, since different class could be run simultaneously, how can we know the order of these states?

The solution is that we add collaboration and sequence diagram in xtUML. These can show how human involved in the system and the sequence of these states.

During the workshop, our group have drawn both collaboration and sequence diagram, what we found was that these diagram should be based of the xtUML class model and state model. The signal in these diagram should be the same. Also, once we understand the state and the process clearly, then it is not a problem to finish these diagrams without an error.

Personally, executable specification is rely on the previous four topic, it helps us understand the relationships between these models.