Parallel Composition using Event-B
User:Renato at Southampton is in charge of the Parallel Composition using Event-B.
Composition is the process by which it is possible to combine different sub-systems into a larger system. Known and studied in several areas, this has the advantage of reusability and combination of systems especially when it comes to distributed systems. While applying composition, properties must be maintained and proofs obligations need to be discharged in order for the final result to be considered valid. Our goal is to add this feature to the Rodin Platform (using Event-B notation) and study the concerns, properties, conditions, proof obligations, advantages and disadvantages when create/analysing system specifications. Since the composition maintains the monotonicity property of the systems, the sub-systems can be refined independently on a further stage, preserving composition properties.
A machine S with events e1, e2, e3 and e4 and variables v1, v2 and v3 can be decomposed using event (de)-composition of event e2 (as can be seen above). This would result in the machine S1 and S2 that have a partial part of the event e2: machine S1 has the part related to the variable v1 (e2') and machine S2 has the part related to the machine v2 (e2''). Also some other events are separated (e1 and v1 only exist on machine S1 and events e3 and e4 with variable v3 only exist on the machine S2) as can be seen above.
A document with information about parallel composition using Event-B is available here: Composition using Event-B Notation.pdf.
A release of the composition plugin for Rodin 0.8.2 is available (email me:ras07r@ecs.soton.ac.uk).
A release for Rodin 0.9 should be available soon (possibly from the main Rodin updates link).
How to use it:
- To install the plug-in, just unpack the context of the zip file ( a folder called 'plugins') into the plugins folder of the Rodin platform. So after this operation, this two files should be seen on the Rodin's plugins folder:
- ac.soton.composition.core_0.0.2.jar
- ac.soton.composition.ui_0.0.2.jar
(Previous point just applies if not using the main Rodin update link)
- To create a new composition file (bcp file), go to Toolbar (on top), New>>Other... Event-B>>Composition Machine. Then select the project (if not selected already) and filename (by default is cm.bcp).
- Bcp files are not visible on Event-B perspective. So to edit, go to Resource or Java perspective and edit the file there.
- After editing the properties of the bcp file, you can generate a new bum file (machine), by using the green button on the toolbar (CM - symbol of machine) or by right clicling on the bcp file and choose the option :'Create Composed Machine'. You will have to introduce a name for the new machine (although a name is suggested by default, but may already exist) and after that is just press 'OK'.
