Requirements Modeling Framework (RMF)

Over the last few months some guys at itemis and Düsseldorf University have been working closely to bring out a solution to the open in an effort to lessen the big gap we have currently in Eclipse Ecosystem in the area of Requirements Management (RM). Requirements Modeling Framework (RMF) has been proposed to Eclipse Foundation as an open source project under Model Development Tools Project.

Scope of RMF

The scope of the project, as described in the proposal, is to provide an implementation for the OMG ReqIF standard (just as the Eclipse UML2 project provides an EMF based metamodel for OMG UML). Requirements management tools could then base their implementation on the provided ReqIF metamodel. It is also in the scope of the project to deliver a requirements authoring tool, again based on the ReqIF metamodel and optionally a generic traceability solution.

Significance of ReqIF

ReqIF (Requirements Interchange Format) is an open standard from OMG for requirements exchange (I had blogged a while ago on how we arrived at ReqIF (earlier called RIF)). Many tools like DOORS already support a snapshot export to this format. Having an EMF based metamodel for ReqIF, opens up the Eclipse framework for integration and new tool development in the area of Requirements Engineering.

ReqIF in a nutshell

ReqIF offers a generic metamodel to capture requirements (The generic nature is at times highly criticized. More on that later). The figure above shows a bird’s-eye view of the metamodel. The metamodel allows creation of requirement types (SpecType) with different attributes types and also instances for it (SpecObject). Since ReqIF also carries the metadata (in the form of SpecTypes), it makes it possible for any tool that understands ReqIF to process the data.

ReqIF also allows creating hierarchy for requirements, grouping them and controlling user access. To support rich text, the metamodel reuses XHTML.

Generic nature and “meta”ness of ReqIF

Anyone expecting a requirements metamodel might be surprised at first when they have a look at ReqIF. You hardly find a term called “requirement” in there. ReqIF is more at a higher meta-level, that is M1. It has been designed this way for a reason.

Requirements Management is an evolving field and until recently never crossed company boundaries. With tighter collaboration between partner companies the benefits of applying RM across company borders became known. The field being highly dominated by commercial products gave barely any chance for standardization. A group of companies in the automotive field, realized that with such a diversity existing hardly any unification is possible. They gave birth to this generic requirements interchange format which was later adopted by OMG and standardized.

The generic structure of ReqIF allows companies to use the tools of their choice to do requirements management and use ReqIF as the standard exchange mechanism and even do round trips. ReqIF is not the only standard to allow this generic nature in the field of Requirements Engineering. DOORS, for example, has an extensible database allowing users to add/delete attributes. The changes to the schema are often communicated to the partners by external means to replicate the changes in their database. Since ReqIF carries the meta-information with it, the changes are migrated automatically across tools/company boundaries. Transmitting the meta-information in ReqIF could however be controlled by tooling. This nevertheless would beat the purpose of ReqIF.

It is also questionable, why such a generic model is required when we have metamodels like UML or EMF already available. The reason for this is very much the same as why EMF co-exists with UML. ReqIF is not a general purpose modeling language like UML or EMF, but more focused on requirements domain.

Integrating ReqIF

RMF provides ReqIF as an EMF based metamodel. This could be used by tool vendors as the internal tool model or an export model by means of model to model transformation. The provided loaders and serializers make sure that the ReqIF file is read/written according to the ReqIF XML Schema.

Using ReqIF natively brings all the advantages of ReqIF to the tooling as well. For example, ReqIF based tools could model the requirements domain of the company within the tooling and share it with partners along with the instance data.

What next?

The initial code contribution is planned by early August 2011 and will be made available as soon as the IP review at Eclipse is complete. If you have any suggestions/comments about RMF, would like to contribute or like to be listed as an interested party, please provide it here.