SASSY – Analysis, Part 8

Ontologies

In their papers [BER06] and [HAP06] four different purposes are proposed for using ontologies:

• Ontology–driven development (ODD): ontologies are used at development time to describe the domain.
• Ontology–enabled development (OED): ontologies are used at development time to support developers with their activities.
• Ontology–based architectures (OBA): ontologies are used at run time as part of the system architecture.
• Ontology–enabled architectures (OEA): ontologies are used at run time to provide support to the users.

The SASSY project aims to demonstrate how ODD and OED can be used during the architecture phase of development. Of course this means that the SASSY project itself will also use OBA and OEA.

Data Dictionary

An ontology (ODD) can be used to describe the problem domain. [HAP06] For projects beyond a certain size a simple glossary of terms ceases to be of much value. Once the project has got to the size where it becomes difficult to remember all the names of things you need something more than the ability to look up by name. An ontology with its more structured and linked view can make finding things easier.

The ontology also allows you to capture the relationships between objects, and, using data properties, it allows you to begin the object modelling.

Requirements

The requirements for a very large system can become a huge document in its own right. It is also common for there to be relationships between the requirements. Thus the requirements are another candidate for an ontology (ODD). [HAP06]

The ability of the Web Ontology Language (OWL) to import one ontology into another means that a requirements ontology can be imported into other ontologies, such as the software architecture ontology and the traceability ontology.

There are quite a large number of possible Quality Requirements that might be considered when creating the requirements document for a system. An ontology (OED) of documented candidates can be referenced during the development of the system requirements.

Software Architecture

The Software Architecture discipline has a large body of knowledge that might be more useful as an ontology (OED). The SASSY project aims to demonstrate the utility of such a collection.

There should be a static ontology that encapsulates the discipline, and a second that captures the specifics of the project.

Since OWL allows ontologies to be imported into other ontologies it might be sensible to partition the SA discipline into several smaller ones.

Traceability

For many systems it is important to know how each component depends on the system requirements. There is rarely a one-to-one mapping from requirements to components, or lines of code, so some way of capturing these relationships seems to be called for. An ontology (OED) seems like a candidate, and the SASSY project should support tracing requirements through the architectural design phase.

Configuration Management

When a large system is being developed by multiple teams, working at differing rates, perhaps even on completely different increment cycles it can become “interesting” trying to keep track of which combinations of components are known to work together (or not).

An ontology, with its ability to handle a large variety of relationships, seems like a good fit to the configuration management problem.



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References

BER06: Julita Bermejo Alonso, Ontology-based Software Enginnering, 2006
HAP06: Hans-Jörg Happel, Stefan Seedorf, Applications of Ontologies in Software Engineering, 2006