ISO/IEC JTC1/N2802, PROPOSAL FOR A NEW WORK ITEM

ENHANCEMENTS TO LOTOS.

1993-12-16     ISO/IEC JTC 1 N 2802

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PURPOSE 

The OSI specification language LOTOS (IS 8807) has reached a good
level of acceptance and recognition within ISO,CCITT, and in
industrial environments. Considerable experience in the use of the
language exists in many organizations. Feedback from the users
indicates that the usefulness of the language is limited by certain
characteristics relating both to technical capabilities and
user-friendly presentation of specifications in LOTOS.

The draft answer of question Q1/48.6 as raised by SC21 WG1 has
received a strong support (11 approvals). As well member body
contributions have been received containing concrete proposals for
enhancements. The acceptance of this NWI will close question Q1/48.6.

Therefore a new work item on LOTOS enhancements should be initiated
without delay so that non-standard extensions to the language do not
become entrenched, which would reduce the overall effectiveness of the
standard. Furthermore the acceptance of the language itself may
stagnate as users become aware of its limitations. It should be noted
that the CCITT language SDL, approved for use in OSI together with
LOTOS and Estelle, has been evolving since 1976 to keep in step with
technology advances. It is therefore to be expected that LOTOS as well
will require ongoing maintenance and enhancement to remain relevant
and useful as a formal specification language.

Industry will be the main beneficiary of the new standard. The
enhancements proposed have been strongly requested by industry.

There exists a sound technical basis, which has been developed over a
number of years and which shows that the proposed enhancements are
feasible.

Therefore the technology can be considered stable and so the
enhancements are timely.

No harmonization with existing regulation is required.

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SCOPE

In the light of member body comments the scope of the proposed new
work item is defined by the following list of enhancements to be
defined:

1. Data-type enhancements.

    A more user-friendly notation for data-type descriptions will be
    defined. This will consider:

    - a. Built-in types (e.g. booleans, characters, bits, integers,
         enumerations, possible reals).
    - b. Composed types (e.g. records, unions, sets, arrays, strings,
         character strings, bit strings).
    - c. Partially defined functions or subtyping.  d. Constructive types.
    - e. Interface with data types in other languages: e.g. ASN.1, SDL.

2. Introduction of modules.

    A means to compose a specification from pre-existing modules will be
    defined to promote reusability and structuring.  This will consider:
    data/process modules, information hiding, abstraction, object
    orientation.

3. Structure of events and true parallelism.

    Mechanisms will be considered to remove the inability to express
    partial synchronization and data exchange.  This includes: compound
    events, gate typing, generalized termination and enabling, modelling of
    true parallelism, dynamic configuration.

4. Non-functional extensions.

    Enhancements will be considered to allow specifying time and
    priorities.  This has many applications in the area of protocols, ODP,
    telephony, real-time, testing.

All enhancements to be defined shall meet the following requirements:

    They shall maintain the existing LOTOS properties which support design
    and engineering procedures, i.e. for refinement, behavioural
    compatibility, executable specifications, for test derivation and
    proper tool support.

    The enhancement to LOTOS shall progress the definition of the textual
    version of the language together with the graphical version (GLOTOS).

    The enhancement to LOTOS shall ensure compatibility with the LOTOS
    base standard.

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