problems in a recent book on UML



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Anil John Saldhana (jsaldhan@eecs.uic.edu)
Tue, 20 Jun 2000 22:23:34 -0500 (CDT)


Hello pUML members, there is a recent book on UML related stuff - "Douglass, Bruce Powel. Doing Hard Time: Using Object Oriented Programming and Software Patterns in Real Time Applications. Reading, MA: Addison-Wesley, 1998." I found a few problems in this book. I wanted to know if any of you had made any reference to this book and were using it. The problems are listed below. If one of you could verify this and get back, it may be useful for a lot of people who are going to refer to this example in this book. ------------------------------------------------------------------------- The example on Space Craft Manoevering in chapter 9 has design flaws. The system will deadlock under the following conditions: 1. Trajectory Planner is in the state "Trajectory Ready". There is a signal "evAbort". Hence all the other subsystems abort. But the Planner is still waiting for somebody to take its plan. So during the next goal phase, the system will deadlock, because the Planner is still waiting. 2. If the Rocket is in the state "Preparing" and there is a signal "evAbort", everybody aborted but the Rocket is still waiting for a signal "evBegin". So, the next time the controller sends a signal "evStartup", the Rocket is still busy "Preparing". These are the faults I think are there.... What says thou? ------------------------------------------------------------------------- with regards, John Anil Saldhana


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