Systems
DATEX
DATEX is a traffic and travel data exchange mechanism, designed and developed over the last ten years by a European task force set up to standardise the interface between inter-regional Traffic Control Centres. In simple terms DATEX enables the exchange of traffic and travel data between suppliers and users (clients) in a defined, structured and understandable way. A fundamental element of DATEX is the DATEX data dictionary, which defines the logical data structure and the terminology used, covering road traffic event and status information. It has been designed to be flexible, using a structure that allows for growth and enhancement of the scope of the defined data. Inherent within DATEX, TCP-IP is recognised as a de facto standard. Further information on DATEX can be found at http://www.datex.org.
DATEX-Net
In order to make the exchange of messages as widely understood as possible and to reduce the number of interfaces required between potential suppliers and clients, standardisation work resulted in the Data Exchange Network (DATEX-Net) Specifications for Interoperability. These specifications present a set of basic tools to develop a common interface including a common Data Dictionary, a common set of EDIFACT messages and a common Geographical messaging system. DATEX-Net has evolved as a European pre-standard protocol for information exchange between traffic control centres in Europe.
The specification and codification of messages within DATEX-Net is based on the ISO standard EDIFACT (Electronic Data Interchange for Administration, Commerce and Transport). This standard specifies the interchange structure in terms of standard segments and data elements. EDIFACT is an Electronic Data Exchange (EDI) standard developed from two widely used standards - the American JEDI and the United Nations standard for Europe.
DATEX-ASN
DATEX-ASN is messages created using the DATEX Data Dictionary but defined using Abstract Syntax Notation One (ASN.1) instead of EDIFACT. Hence the DATEX Data Dictionary and location referencing system are used but the message semantics is ASN.1 with standard encoding rules. DATEX-ASN has been produced as a draft ISO standard ISO/DIS 14827-2.
ASN.1 is a language for describing structured information, typically information to be conveyed across some interface or communication medium. ASN.1 presents a standard notation for the definition of data type and values.