Author Topic: Link to Element feature  (Read 3196 times)

Glassboy

  • EA User
  • **
  • Posts: 898
  • Karma: +52/-54
    • View Profile
Link to Element feature
« on: August 05, 2016, 12:01:56 pm »
is there a UML reason that an self referential association can't link to an element feature of itself, or is it an EA reason?

Paolo F Cantoni

  • EA Guru
  • *****
  • Posts: 5882
  • Karma: +71/-79
  • Inconsistently correct systems DON'T EXIST!
    • View Profile
Re: Link to Element feature
« Reply #1 on: August 05, 2016, 05:09:35 pm »
is there a UML reason that an self referential association can't link to an element feature of itself, or is it an EA reason?
AFAIK, its EAUI.

Report the bug and we can support...

Paolo
Inconsistently correct systems DON'T EXIST!
... Therefore, aim for consistency; in the expectation of achieving correctness....
-Semantica-
Helsinki Principle Rules!

Geert Bellekens

  • EA Guru
  • *****
  • Posts: 7752
  • Karma: +165/-21
  • Make EA work for YOU!
    • View Profile
    • Enterprise Architect Consultant and Value Added Reseller
Re: Link to Element feature
« Reply #2 on: August 05, 2016, 05:41:36 pm »
I don't see why there should be a UML reason.

Geert

qwerty

  • EA Guru
  • *****
  • Posts: 8972
  • Karma: +136/-124
  • I'm no guru at all
    • View Profile
Re: Link to Element feature
« Reply #3 on: August 05, 2016, 06:52:29 pm »
Is the "Link to element feature" in the UML specs at all? ICR

q.

Geert Bellekens

  • EA Guru
  • *****
  • Posts: 7752
  • Karma: +165/-21
  • Make EA work for YOU!
    • View Profile
    • Enterprise Architect Consultant and Value Added Reseller
Re: Link to Element feature
« Reply #4 on: August 05, 2016, 07:08:32 pm »
Is the "Link to element feature" in the UML specs at all? ICR

q.
There where reasons to believe it was not against the rules IIRC

Geert

qwerty

  • EA Guru
  • *****
  • Posts: 8972
  • Karma: +136/-124
  • I'm no guru at all
    • View Profile
Re: Link to Element feature
« Reply #5 on: August 05, 2016, 07:49:04 pm »
I just skimmed 2.5 but could not find any trace of that notation. Sure, you can place a connector anywhere outside an element. But the open rectangle inside - I could not spot that. It's probably in the same category as
  • italic notation of general class top right
  • the "lying eight" for the composition (which at least has been used once in a spec without any further explanation)

I asked that once: is a tool compliant if it allows more than the specs? Probably the answer is: there is no compliance anywhere. One has to few, others have too much implemented. So exchange between tools is always connected with information loss. Anyhow, I think there should be a place where is stated what is outside the official specs. Means: the plus and the minus.

q.

Glassboy

  • EA User
  • **
  • Posts: 898
  • Karma: +52/-54
    • View Profile
Re: Link to Element feature
« Reply #6 on: August 08, 2016, 07:22:06 am »
bug report logged.

Simon M

  • EA Administrator
  • EA Guru
  • *****
  • Posts: 6200
  • Karma: +47/-5
    • View Profile
Re: Link to Element feature
« Reply #7 on: August 08, 2016, 08:53:47 am »
The notation used isn't part of the spec. Dependencies between features are, but no notation is described.

Why it's not supported for self relationships comes down to how it's going to enhance diagrams.
« Last Edit: August 08, 2016, 09:05:16 am by Simon M »
Simon

support@sparxsystems.com

Glassboy

  • EA User
  • **
  • Posts: 898
  • Karma: +52/-54
    • View Profile
Re: Link to Element feature
« Reply #8 on: August 08, 2016, 09:52:54 am »
The notation used isn't part of the spec. Dependencies between features are, but no notation is described.

Why it's not supported for self relationships comes down to how it's going to enhance diagrams.

I'm trying to create a pretty view of FIBO.  There's multiple instances where elements have attributes that relate to other attributes.  It's much neater and more informative to be able to link to the feature and show it on a diagram.

Paolo F Cantoni

  • EA Guru
  • *****
  • Posts: 5882
  • Karma: +71/-79
  • Inconsistently correct systems DON'T EXIST!
    • View Profile
Re: Link to Element feature
« Reply #9 on: August 08, 2016, 10:11:42 am »
The notation used isn't part of the spec. Dependencies between features are, but no notation is described.

Why it's not supported for self relationships comes down to how it's going to enhance diagrams.
???????    :o

Now we're back in animal farm...  All elements are are equal, but some are more equal than others...

Surely it provides the SAME information as between separated elements...  THIS feature is related to THAT feature!

Thought experiment: bring the two connected elements together so that they eventually overlay each other.  At what point did it stop enhancing the diagram?

Paolo
Inconsistently correct systems DON'T EXIST!
... Therefore, aim for consistency; in the expectation of achieving correctness....
-Semantica-
Helsinki Principle Rules!

Glassboy

  • EA User
  • **
  • Posts: 898
  • Karma: +52/-54
    • View Profile
Re: Link to Element feature
« Reply #10 on: August 08, 2016, 11:33:35 am »
I suspect what Simon is actually saying is that every new feature of the product has a cost related to it and that there needs to be a reason to invest in doing it.  When we suggest new features we need to be cognisant that they may mean that other features we'd like to see don't get done.

Paolo F Cantoni

  • EA Guru
  • *****
  • Posts: 5882
  • Karma: +71/-79
  • Inconsistently correct systems DON'T EXIST!
    • View Profile
Re: Link to Element feature
« Reply #11 on: August 08, 2016, 02:30:32 pm »
I suspect what Simon is actually saying is that every new feature of the product has a cost related to it and that there needs to be a reason to invest in doing it.  When we suggest new features we need to be cognisant that they may mean that other features we'd like to see don't get done.
It's a bug joyce,  not a new feature...  :D

Paolo
Inconsistently correct systems DON'T EXIST!
... Therefore, aim for consistency; in the expectation of achieving correctness....
-Semantica-
Helsinki Principle Rules!

Simon M

  • EA Administrator
  • EA Guru
  • *****
  • Posts: 6200
  • Karma: +47/-5
    • View Profile
Re: Link to Element feature
« Reply #12 on: August 08, 2016, 05:11:22 pm »
Yes, there is a cost associated with implementation (and maintenance) of every feature added. This can be offset by a corresponding reduction in support costs. At the risk of being flamed, the same can be said of bugs fixed.

Originally, link to element feature was added for users requesting the ability to join two attributes on different classes (tables etc.) and there was no need to handle self-connectors for this use case. Obviously, it was considered because the menu item is disabled.

Now expecting flames... Given how long the feature has been in there and this is the first request I am aware of asking for adding it to self-connectors, I would consider it a reasonable decision.

I'm not saying there is no value in the feature, or that it couldn't be used to enhance a diagram. Thanks for the explanation of how you want to use it with FIBO. That provides us with a useful scenario of how you want to use it.
Simon

support@sparxsystems.com

Paolo F Cantoni

  • EA Guru
  • *****
  • Posts: 5882
  • Karma: +71/-79
  • Inconsistently correct systems DON'T EXIST!
    • View Profile
Re: Link to Element feature
« Reply #13 on: August 08, 2016, 05:34:50 pm »
This is the first time anybody's complained.  It's almost certainly not the first time it was needed.

This bug is just symptomatic of the doubtful implementation of the reflexive relationship.

Not a flame, just an observation.

Bugs reveal design flaws (once the implementation flaws have been removed).  That's what bothers us.

As I've said before, (we) developers design in bugs.  Until we understand that, we're not doing our jobs properly.

Paolo
Inconsistently correct systems DON'T EXIST!
... Therefore, aim for consistency; in the expectation of achieving correctness....
-Semantica-
Helsinki Principle Rules!

Glassboy

  • EA User
  • **
  • Posts: 898
  • Karma: +52/-54
    • View Profile
Re: Link to Element feature
« Reply #14 on: August 09, 2016, 07:08:55 am »
I'm not saying there is no value in the feature, or that it couldn't be used to enhance a diagram. Thanks for the explanation of how you want to use it with FIBO. That provides us with a useful scenario of how you want to use it.

I suspect that one of the reasons I expected it to be there is my long familiarity with schemas like the Active Directory schema.  You have forward and backward links between user objects for relationships like Managed by and Secretary.  Modelling these internal relationships would seem to come before modelling external relationships :-)