Protocol Specification Languages

 
 
 
 

Protocol specification languages provide precise notations to facilitate implementation of standards and enhance technical quality. As their syntax and semantics are precisely specified, every word and symbol has a well-defined meaning and its use must follow exact rules. This makes standardized specifications unambiguous while improving intuitiveness, increasing consistency and making it possible to detect errors during standardization rather than implementation.

Manufacturers who use precise and graphical languages report good results and considerable productivity gains. Their use within standardization is increasing along with the generally increased acceptance of such techniques.

SDL, MSC, ASN.1, TTCN and UML are all languages, which ETSI recommends for use within telecom standards, particularly those specifying protocols. Each specification language offers different facilities which are valuable to standards writers. Thus, an optimum combination of languages needs to be found.

Further details are given on the page dedicated to each language, however, the principal uses of each language are as follows:

  • SDL (Specification and Description Language): for the description of architecture, behaviour, data and static interface
  • MSC (Message Sequence Chart): for the description of typical or exceptional message exchanges between entities
  • UML (Unified Modelling Language): for the collection, analysis and processing of requirements as well as for the specification message exchanges and overviews of architecture and behaviour specifications
  • ASN.1 (Abstract Syntax Notation One): for the description of the data structures carried by messages exchanged between communicating parts
  • TTCN (Testing and Test Control Notation): for the specification of test cases, test suites and test configurations.

However, applying a language does not guarantee success if it is being used in a bad way or if the working method is ineffective. In order to combat these potential hazards, ETSI has produced guidelines for how the languages should be used for standard specifications. These are summarized in the table below. For more detailed advice, consult the 'Making Better Standards' website, which provides guidance and assistance to anybody involved in writing communications standards.

List of ETSI Guides giving guidelines on how specification languages should be used for standard specifications :

TitleUMLSDLMSCASN.1TTCNDocument
General use of SDL, MSC and ASN.1   v v v   EG 201 383
Descriptive SDL   v v v   EG 202 106
SDL Handbook   v v v   ETR298
Validation of SDL in standards   v       EG 201 015
Object-orientation in standards making v v       EG 201 872
Guide to the use of TTCN-2       v v EG 202 103
 

The following is a list of recently published and frequently downloaded standards. Please use the ETSI Work Program to find further related standards.

Standard No.     Standard title
ETS 300 406Protocol and profile conformance testing specifications;
Standardization methodology
EG 201 058Implementation Conformance Statement (ICS) proforma style guide
EG 201 383Use of SDL in ETSI deliverables;
Guidelines for facilitating validation and the development of conformance tests
EG 202 106Guidelines for the use of formal SDL as a descriptive tool
ETR 298Specification of protocols and services;
Handbook for SDL, ASN.1 and MSC development
EG 201 015Specification of protocols and services;
Validation methodology for standards using Specification and Description Language (SDL); Handbook
EG 201 872Methodological approach to the use of object-orientation in the standards making process
EG 202 103Guide for the use of the second edition of TTCN