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  1. OMG Issue

SYSML17 — The SysML classification of properties is incomplete

  • Key: SYSML17-100
  • Legacy Issue Number: 18709
  • Status: open  
  • Source: NASA ( Nicolas Rouquette)
  • Summary:

    SysML 1.3 section 8.3.2.2 Block says:

    SysML establishes four basic classifications of properties belonging to a SysML Block or ValueType.
    …
    A property typed by a SysML ValueType is classified as a value property, and always has composite aggregation.

    In SysML, we also have Signals.
    In UML, Signals can have properties.

    How does SysML then classify properties defined in a Signal?

    A very strict reading of the SysML spec would suggest that a Signal cannot have any kind of SysML property because a Signal is neither a SysML Block nor a SysML ValueType.
    However, this is clearly too restrictive in practice.

    I propose expanding SysML's classification of properties to include SysML Blocks, ValueTypes and Signals.
    This leads to another question:

    What are the legal types of a property belonging to a Signal?

    I propose restricting such properties to be typed by SysML ValueTypes only. This corresponds to the practical situation where a Signal carries a data payload – I.e., it is a message with some data content.
    Allowing a property belonging to a Signal to be typed by a SysML Block or Signal leads to semantic problems — what would it mean to send / receive such signals?

  • Reported: SysML 1.4 — Mon, 13 May 2013 04:00 GMT
  • Updated: Thu, 31 Jan 2019 14:40 GMT