Overview
ISO/IEC 14750:1999 - also published as ITU‑T Recommendation X.920 - defines the Open Distributed Processing Interface Definition Language (ODP IDL). The standard provides a language- and environment‑neutral notation for describing computational operation interface signatures within the ODP Reference Model (see ISO/IEC 10746-2 and ISO/IEC 10746-3). Use of ODP IDL specifies operation parameters and interface contracts without mandating any particular runtime mechanisms or communication protocols.
Key topics and technical requirements
- Purpose: Describe interface signatures for client and object interactions in distributed systems (ODP).
- Language design: ODP IDL’s grammar is a subset of ISO/IEC C++ with additional constructs for distribution; it is descriptive (no algorithms).
- Lexical rules and character set: Uses the ISO/IEC 8859‑1 (Latin‑1) character set and follows C++ lexical conventions for identifiers, tokens, comments and literals.
- Preprocessing: Supports C++-style preprocessing - file inclusion, macro substitution and preprocessor tokens (#, ##, include, define, pragma).
- Tokens and syntax: Defines token types (identifiers, keywords, literals, operators, separators) and EBNF-like grammar notation for syntax description.
- Identifiers and namespaces: Single namespace for identifiers; case-insensitive collisions are detected; identifiers must begin with a letter and may include underscores and digits.
- Keywords and constructs: Provides keywords such as Object, interface, attribute, Exception, and others for defining interfaces, attributes (accessors), exceptions (named termination), operations and types.
- Literals and escapes: Integer, floating-point, fixed-point, character and string literal rules; escape sequences (e.g., \n, \t, \xhh) and rules for wide characters.
- Semantics: Fully specifies each operation’s parameters and interface signatures; normative and informative annexes clarify specifics.
Applications and target users
- System architects and designers who need a neutral formalism to specify distributed system interfaces consistent with the ODP Reference Model.
- Standards bodies and specification authors creating interoperable interface descriptions across languages and platforms.
- Middleware and tools vendors that implement or validate interface definition processing or generate language bindings (given ODP IDL’s C++-aligned syntax and preprocessing model).
- Integrators and implementers documenting interface contracts where protocol-agnostic definitions are required.
Related standards
Keywords: ISO/IEC 14750, ODP IDL, Interface Definition Language, Open Distributed Processing, interface signatures, ISO/IEC 10746, ITU‑T X.920, language-neutral interface specification.
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