Browse Prior Art Database

Transition Control Statements for State Models

IP.com Disclosure Number: IPCOM000116898D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 106K

Publishing Venue

IBM

Related People

Hill, GP: AUTHOR [+2]

Abstract

In an object oriented analysis model, an active object's State Transition Diagram (STD) is used to create its detailed State Event Matrix (SEM). The SEM must be manually edited and maintained to include other state transitions that represent exception conditions. A method of reducing the manual effort by expressing these exceptions transitions with simple transition control statements is disclosed.

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This is the abbreviated version, containing approximately 52% of the total text.

Transition Control Statements for State Models

      In an object oriented analysis model, an active object's State
Transition Diagram (STD) is used to create its detailed State Event
Matrix (SEM).  The SEM must be manually edited and maintained to
include other state transitions that represent exception conditions.
A method of reducing the manual effort by expressing these exceptions
transitions with simple transition control statements is disclosed.

      In an object oriented analysis model, an active object's State
Transition Diagram (STD) is used to initially create its State Event
Matrix (SEM).  Since the SEM is typically very sparse, it must be
manually edited to include other state transitions such as:
  o  Add common transitions for events like Reset_Object or
      Abort_Operation that if explicitly placed on the STD would make
      it appear too cluttered to be usable.  This operation is
      equivalent to filling in the column of next states associated
      with an event.
  o  Set unexpected transitions to default to the Illegal_Transition
      state as a global mechanism to detect unspecified transitions
      (i.e., defects).

      Unfortunately, when a change is made to the STD, the SEM must
be recreated and manually edited again.  Defects could easily be
introduced while the SEM is being manually restored to its previous
contents.

      To reduce the amount of manual work involved and the chance of
error, STD Transition Control Statements (TCS) have been developed.
Transition Control Statements (TCS) are written directly on the
object's STD as unbounded text (i.e., not inside a box defining a
state).  They are placed directly under the object name text in a
single block of text as shown in the following generic example:
        XXX-s1;Z
    Object_Name
  *This area may be used for a short description or comment about
the model*
        DEFINE_TCS
    ADD_COMMON_TRANSITIONS(Event_Name, Next_State)
    ADD_COMMON_TRANSITIONS(Event_Name, Next_State)
    ADD_TRANSITION(State, Event_Name, Next_State)
    ADD_TRANSITION(State, Event_Name, Next_State)
    ENDEF_TCS
      *Additional design comments about this STD if required*

The following transition control statements are defined:
        DEFINE_TCS

      This statement defines the beginning of the transition control
statements for this object.  It must be the first statement in the
block of TCS for an object.
        ADD_COMMON_TRANSITIONS(Event_Name, Next_State)

      This statement causes all state transitions associated with
"Event_Name" that are not explicitly defined by the STD to be set to
"Next_State."  If "Event_Name" does not already exist on the STD then
the extraction tools can automatically create it by adding another
column to the STA wi...