Preface to the Third Edition


The UML is an evolving standard. This has, of course, both pros and cons. One of the cons is that it keeps changing, but I believe this is more than offset by the primary pro that the standard continues to improve. Since the second edition of Real-Time UML, some important changes to the UML have taken place.

The most important of these is the UML 2.0. At the time of this writing (summer 2003), the UML 2.0 specification has been "voted to adopt." This means that the UML 2.0 has been accepted by the Object Management Group and, pending a couple of more votes, is ready to begin the finalization process to make it into a released standard. This finalization process may take a year or more but hopefully a bit less. The UML 2.0 is an incremental improvement to the UML 1.x standards, improving the clarity of the UML for capturing architectures and improving its scalability. Because the UML 2.0 still must undergo the finalization process to remove defects and make it more consistent, the released standard may differ somewhat from what is described in this book. Nevertheless, I believe such differences will be small and relatively insignificant.

The other improvement for the real-time community at least, is the adoption of the UML Profile for Schedulability, Performance, and Time (the so-called Real-Time Profile [RPT]). This profile uses the standard lightweight extension mechanisms of UML 1.x to provide a standard set of tags for capturing schedulability and performance constraints of systems. Although the profile doesn't add any new capabilities to the UML, it does provide a standard way of capturing the timeliness quality of services aspects so that tools can exchange models and understand the timeliness constraints when they do so. This means that schedulability and performance analysis tools can read UML models (compliant with the profile) and then perform mathematical analysis of these models.

The UML continues to gain momentum in the world of real-time and embedded systems, particularly complex ones. For this reason, I have included a Special Topics chapter at the end that shows how to represent C4ISR (Command, Control, Communications, Computers, Intelligence and Reconnaissance) architectures with the UML. C4ISR systems are among the most complex software systems on the planet but the C4ISR standard was released about the same time as the original UML standard, so they have not been previously discussed together.



Real Time UML. Advances in The UML for Real-Time Systems
Real Time UML: Advances in the UML for Real-Time Systems (3rd Edition)
ISBN: 0321160762
EAN: 2147483647
Year: 2003
Pages: 127

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