SDL-News: A question about state aggregation in SDL-2000

Subject: SDL-News: A question about state aggregation in SDL-2000
From: Jacqueline Floch (
Date: Tue Nov 06 2001 - 14:59:59 GMT

Become an SDL Forum Society member <>
The originator of this message is responsible for its content.
-----From Jacqueline Floch <> to sdlnews -----

Dear SDL users,

I am currently actively experimenting with SDL 2000 - and have a
question(s) about state aggregation in SDL-2000. I do not understand the
reasons for the choices done by the Study Group 10, and expect some
feedback from an SDL expert. There are possbly other SDL users that wish to
contribute to the discussion.

 From Z.100 section 11.11.2 State aggregation:
* All entry and exit points of the both the container state and the state
partitions must appear in exactly one Connection-definition.
* If different partitions exit the composite state through different exit
points, the exit point of the composite state is chosen in a
non-deterministic way.

I wish to "combine" exit points of the state partitions in a flexible way,
and use the same exit point - in combination with several different exit
points from other states - in different connections. Is this need shared by
any other SDL user? Why does Z.100 set a retriction on the appearance of
exit points in the definition connection?

The restriction set by Z.100 - on using exit points in connection - is
problematic in the case the state partitions are defined with different
numbers of exit points. For example, if one state partition has two exit
points, while another one three exit points, it is not possible to describe
all possible connections (i.e. 2 x 3). If the states were modelled
independently, aggregating them will necessarily lead to non-deterministic
exit from the state aggregation. I wonder if this has been discussed in the
study group 10?

I have considered an extension to SDL state aggregation where exit
conditions of the state aggregation can be expressed as logical expressions
(using the logical operators not, and, or) of the exit conditions of the
state partitions. Has this kind of connection been discussed
within the Study Group 10?

Thank you in advance for feedback,
Jacqueline Floch.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~
Jacqueline Floch Tel: +47 73 59 30 12
ITEM, NTNU Fax: 73 59 44 66
N-7491 Trondheim, Norway Priv: 73 51 52 77
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~

--End text from Jacqueline Floch <> to sdlnews ---
For extra SDL Forum Society benefits join at <>

This archive was generated by hypermail 2a23 : Thu May 09 2013 - 16:05:49 GMT