Analysts have warned users that the new version of the Unified Modelling Language (UML) methodology is not backwards compatible, and they would be better off not using it until the specification stabilises.
The problem centres around four areas. There have been changes in the semantics of the methodology?s syntax and in descriptions of how systems, subsystems and model elements relate to each other.
Model management and the concept of how systems, subsystems and models relate to each other has been clarified, as have the descriptions of activity diagrams.
Collaboration and interaction and how to define systems from the perspective of services and processes has been completely revised, with clearer rules about how to construct and maintain consistencies between class and collaboration diagrams.
This means that a Case tool conforming to version 1.1 of the UML specification, which was accepted by the Object Management Group (OMG) as a standard on 17 November, may not work against a diagram written to conform to release 1.0.
The tool would give out not valid or error messages because the meaning of the diagram would have altered slightly. While most suppliers are likely to offer translation tools or bridges, it would require more work for the user to implement them.
Mike Budd, analyst at consultancy Ovum, said: ?Version 1.0 of UML was rushed out and there are areas of significant problems as a result. It was released too early because the companies had deadlines for their OMG standardisation submission and wanted to stick to them.?
But, he explained, the UML market was at a very early stage, and people were potentially going to face the same problems with every new release.
?So, if users are already using a well established, structured method, I wouldn?t advise them to use UML. I should wait until it?s stabilised. Some areas are still unclear and inconsistent and UML is by no means complete yet,? he added.
The backwards compatibility problem would probably hit users gradually as tool vendors upgraded their tools to conform to the new version of the methodology, he continued.
But, to make matters worse, because the UML model is extensible, users are within their rights to start adding proprietary extensions that will make them less portable.
?The onus is on the tools vendors to clarify what is an extension and what may or may not be possible to swap between tools. The extensions are clearly defined in the specification, so they can?t just add what they want, but it?s unlikely they?ll make it clear what are extensions or not because they want lock-in,? Budd explained.
Ian Gavin, UK marketing manager at Rational Software, which developed UML, retorted that users would experience no problems in upgrading to UML 1.1.
?There were two different editors, which are now one, but all the rest of the changes are extensions that weren?t there in 1.0. This means when users run the new release of Rose, it won?t take long to convert the model,? he said.
But he added that version 1.0 of the specification had not been rushed out to ensure it hit the OMG?s submission deadlines, rather it had been presented when Rational thought it was ready. As a result, version 1.1 had only needed some clarification of fuzzy issues and a few extensions.
As for the UML market splintering, he agreed that it could potentially happen, but enforcement of the standard was up to the OMG, which intended to introduce a testing and certification programme over time.
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