UML 2.6 RTF Avatar
  1. OMG Issue

UMLR — we can create an invalid active state configuration

  • Key: UMLR-157
  • Legacy Issue Number: 13449
  • Status: open  
  • Source: International Business Machines ( Adam Neal)
  • Summary:

    The spec states: "An entry point pseudostate is an entry point of a state machine or composite state. In each region of the state machine or composite state it has a single transition to a vertex within the same region." This is slightly ambiguous as one could take it to mean that the region is the region who owns the target dirctly. This would allow one to create the case where we can create an invalid active state configuration. consider: S1's region1 owns S2 and S3 who both have sub verticies. An entry point on S1 should only be able to target one vertex with region1 (either a direct or deeply nested vertex), but not more then one. If the assumption by a user was made that both the verticies in S2 and S3 could be targeted (since they are owned by different regions) then the tooling would essentially be allowing concurrent entries into a single region. Where as, really we need to specify more along the lines of that the LCA region of the source and target may have at most a single transition. An entry point pseudostate is an entry point of a state machine or state. For each transition that targets a vertex in region R, there may not exist another transition targeting a vertex in region R nor any region contained within R. Also, given the alternate semantics of entering a state (that regions don't have to be entered and the state itself can remain active), entry points should not be required on composite states only. Connecting to an entry point with no outgoing transitions or to the state border itself should be considered semantically the same. One usecase for this is that users may define entry/exit code on the state itself to preform some basic behavior, but in redefined contexts want to enhance the behavior by continuing that transition to a sub vertex.

  • Reported: UML 2.2 — Fri, 6 Feb 2009 05:00 GMT
  • Updated: Fri, 6 Mar 2015 20:57 GMT