1. Abstract

Study Group 17, in its role as Lead Study Group on languages and description techniques, leads this project.

The overall objectives are to:

• improve the product engineering process by providing a framework and a set of languages that are smoothly integrated;
• allow easy integration with relevant languages developed and maintained outside ITU-T;
• improve Recommendations, in the sense that they can be more easily implemented as products and that products can be more rigorously tested for conformance.

This project addresses an additional market by branding the set of ITU-T languages and using several languages together to address domains where a single language may not suffice. At the same time, some languages address a specific target market on their own in addition to their usefulness within a language set. Both markets - those for individual languages and those for a language set - are addressed in order to broaden the overall base for the languages. Thus, in addition to the language coordination project, individual projects can prove beneficial and will be encouraged if judged to be so, as in the case of the ASN.1 project.

2. Background

ITU-T is already recommending a long series of formalized languages, such as SDL, MSC, ASN.1, TTCN, ODL, GDMO and CHILL.

Furthermore, it is developing new languages to handle currently unaddressed domains, such as URN, and adopting additional languages, such as IDL, XML, and some UML notations. Other notations are for observation. This effort focused on adopting non-ITU-T languages where they fit into the ITU-T language framework and the further development and maintenance of those that are either already in the core competence of ITU-T or which are not available from outside ITU-T.

As telecommunication becomes increasingly IT-oriented, formalized languages will be used more in the writing of Recommendations and will also be recommended for application in the industry by the language and techniques Recommendations (in particular by SG 17).

There is a need to present the ITU-T languages in a coordinated framework to enable:

• users to understand where they can be used;
• standardization bodies to coordinate and set priorities;

so that everyone can see what is covered or not covered by the ITU-T languages.

The project addresses the need: 

• to present all the languages/notations in a common framework as a coordinated language family;
• to have a common approach to presenting the languages;
• to coordinate methods for use of the languages; and
• to have a common approach to promotion.

3. Task objectives

The task objectives are:

1. Invite, write and collect proposals and integrate them into a project work programme.
2. Coordinate decisions on prioritization of activities within each Question.
3. Follow-up and record work progress.
4. Provide a named (hence easily identifiable and promoted) branding of the ITU-T language family.
5. Provide a framework for languages to be used in software and standards development.
6. Identify a set of languages within the framework, of which a subset is identified for development and maintenance within ITU-T.
7. Identify a list of customers of the framework and of individual languages.
8. Initiate and follow-up development of methodology guidelines for applications, which recommend language use at the various steps and results.
9. Initiate and follow-up development of architecture guidelines (ODP, three-tier, etc.) for applications that recommend language use for the various components and interfaces.
10. Coordinate methodology and architecture frameworks with other SGs.
11. Develop and carry-out a marketing/promotion plan for the integrated ITU-T language family.
12. Integrate the results of the project and provide a procedure or process to maintain and further develop those results after termination of the project.

4. Organization and timing

The project will provide to the closing plenary of each Study Group 17 meeting a status report on plans, work in progress and results. In addition, SG 17 will keep TSAG informed.

Some of the task objectives, such as framework development, require new contributions, while others require coordination across various groups. Therefore, the project is expected to last throughout the current Study Period (2001-2004).

The initial activities planned up to and including the first meeting of SG 17 (27 February - 8 March 2002) were:

1. Collect coordination issues from all SG 17 Questions, ref. Task Objective 1.
2. Propose and decide on a brand name for the ITU-T language family, ref. Task Objective 4.
3. Organize a workshop on language frameworks (Geneva, Saturday 2 March 2002) with contributions from both inside and outside ITU-T.
4. Develop and agree on a work plan for the language coordination project.

• the set of languages as the Unified Language Family (ULF)
• the framework environment for the use of the set of ITU-T languages as The ITU-T Language Environment (TILE)

Under the umbrella of the language project, a new Question on "Grammars for Recommendations defining notations" was approved at the February/March 2002 SG 17 meeting. The results of the Question are expected to be one or more Recommendations that define the meta-grammars used in language Recommendations (for example, a common BNF meta-syntax).

The plan for work upto November 2002 is to:

• Consolidate and refine the contributions from SG 17 Question studies on particular languages (in particular ASN.1, MSC, SDL, TTCN and ODL);
• Initiate study of key concepts crucial for the real-time and telecommunications area (such as signal consumption, time) identify mapping between languages at the semantic level that concentrate on the most important issues, and enabling key terminology to be harmonised to avoid confusion and related behaviour semantics, to determine whether mappings between the languages are realistic.
• Initiate a feasibility study on defining a common mathematical data model for the data languages of ASN.1, SDL and TTCN. If it is decided that this can be done cost effectively, then further work would be done (in the project or as a Question study) to define the model. Such a model would allow unified data notation that can be used with all three languages. A decision would have to be made whether defining yet another data notation might not create more divergence than convergence.

There may be a need for new Recommendations to be developed under this Question. When and if such Recommendations are identified, this will be reported in the plans and reports to SG 17.

5. Project management

The Chairman of Working Party 3/17 "Languages and notations", Mr Rick Reed (TSE Limited, United Kingdom), is appointed as Project Leader. The SG 17 Language Advisory Board (LAB) will act as a reference group for this project.

Attachment

Technical considerations

Generally speaking, each of the notations had previously been developed largely in isolation from other notations used in the engineering process, with the result that integration between the notations was not as good as it could be. The consequence is that where languages overlap, engineers sometimes have to learn two different ways of doing the same thing and choose between them. There are other consequences, such as the same term being used for different constructs in different languages, and different terms being used for the same (or essentially the same) concept in different languages.

To some extent, these problems can be overcome in two ways:

• by using tools that integrate the notations;
• by relating the languages by means of common semantic models.

These two approaches have much in common. It is difficult to integrate notations in tools without implicit or explicit common semantics.

Those who are familiar with the UML notation as standardized by OMG will recognize the above approach. UML originated from a number of separate notations covering different aspects of software engineering. What UML tries to achieve is to unify these notations, thereby making it easier to use them together in a number of engineering activities. UML still has a number of different notations used for different engineering purposes, but these are related to one another through a common model. In terms of general awareness, UML has certainly been a success, in the same way as the Ada programming language became well known. There are many books on UML and several tools that support various interpretations of UML.

Although UML notations have many desirable features, when a comparison is made with the individual notations recommended by ITU-T, such as ASN.1, SDL and TTCN, the current ITU-T Recommendations are either superior for telecommunication applications, or UML (at least currently) offers no alternative. However, it will not be productive to view the situation in terms of competition between UML notations and ITU-T notations: it would be better to have common models between the notations so that they can be used together. For example, there is already Recommendation Z.109, relating SDL and UML, and MSC has much in common with UML sequence diagrams. A common basis between the OMG and ITU-T languages will enable members of both organizations to benefit from tools that support the common model. Some member organizations already recognize the common interest and are participating in both OMG and SG 17.

A further issue that has to be considered by ITU-T is legacy investment. There are many Recommendations and telecommunication products that use existing versions of ITU-T notations. Moreover, engineers in the industry have established expertise in the use of these notations.