anthony@uunet.uu.net (Anthony Lee) (08/18/89)
In the proceedings to the 7th International Conference on Software Engineering for Telecommunications Switching Systems, there is an article by T.F. Bowen et al from Bellcore. The article was called "The Feature Interaction Problem in Telecommunications Systems" The following is a paragraph from the article: >"Automatic verification that specifications are consistent is a promising >approach. But detecting certain kinds of inconsistency may be intractable or >undecidable. There are interactions whose detection appears to require >examination of all possible executions of the system. We call these >"dynamic interactions". To make this idea concrete, suppose that customer >A has automatic "retry on busy", which continues calling a busy line until >it is free, and customer B has automatic "return call if busy", which >remembers a call that arrives when the line is busy and returns it as soon >as the line is free. If A calls B, an infinite cycle of calls could be >initiated, in which B tries to return A's call but A is retrying B, who >remains busy trying to call A. ..... My question is why is it not possible to have the exchange watch for such a situation and cancel either the "retry on busy" or "return call if busy". Is it possible to view the above problem as a deadlock situation ? cheers Anthony Anthony Lee (Humble PhD student) (alias Doctor(Time Lord)) ACSnet: anthony@batserver.cs.uq.oz TEL:(+617) 3712651 Internet: anthony@batserver.cs.uq.oz.au (+617) 3774139 (w) SNAIL: 243 Carmody Rd, St Lucia, 4067 Australia