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Recognized standards

European Standardization Telecommunication Institute (ETSI) defines various protocols and provides conformance test suites to these protocols. They cover very various areas such as LTE (Long Term Evolution of 4G), IPv6, SIP (Session Initiation Protocol), ITS (Intelligent Transportation Systems), IoT (Internet of Things)...

ETSI recommends a number of technologies to define its recommendations such as SDL, TTCN-3, and ASN.1 which happen to be the technological bricks on which PragmaDev Studio is built.

Interface definition

ASN.1 is a joint standard of the International Organization for Standardization (ISO), International Electrotechnical Commission (IEC), and International Telecommunication Union (ITU-T). It is a standardized and portable notation to describe the information exchanged at a system interface.

An ASN.1 description is static but comes with a number of standardized ways to encode and decode the information in a machine independant way. To name a few: BER (Basic Encoding Rule), PER (Packet Encoding Rule), XER (XML Encoding Rule).

ASN.1 is supported by PragmaDev Specifier and PragmaDev Tester in model edition and execution.

Protocol description

SDL (Specification and Description Language) is ITU-T Recommendation Z.100. It is a graphical notation with a formally defined semantic used for the standardization of protocols and services as well as for the specification, the design and the implementation of communicating systems. SDL can be used to describe the behaviour of systems at various levels for the purpose of communication and understanding, or it can be used with a thorough level of details to design a system and generate target code.

PragmaDev Specifier is based on SDL. The dynamic of the protocol can be graphically described with formally defined state machines. Once the syntax is correct a simulator can execute the model and interact with it in order to verify it behaves correctly. When the model is updated, the previously verified scenario can be run again automatically to prevent any regression.

Conformance testing

TTCN-3 is THE standard notation for conformance. In the telecommunication industry ETSI conformance test suites are published in TTCN-3. PragmaDev Tester can edit these test cases, and execute them to run against a model or a real implementation of the system.

ETSI protocol specification languages

The following is an excerpt of ETSI web site:

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:

Title UML SDL MSC ASN.1 TTCN Document
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   ETR 298
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