Call Level Interface

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The Call Level Interface (CLI) is a de facto standard software API for SQL-based database management systems, created by The Open Group. Developed in the early 1990s, the API was defined only for the C and COBOL programming languages. The Call Level Interface defines how the C or COBOL program should send SQL queries to the DBMS and how the returned recordsets should be handled by the application in a consistent way.

The interface is part of what the Open Group refers to as the Common Application Environment, which is intended to be a wide standard for programming open applications, i.e. applications from different programming teams and different vendors that can interoperate in an efficient manner. SQL/CLI provides an international standard implementation-independent CLI to access SQL databases. Client-server tools can easily access databases through dynamic link libraries. It supports and encourages a rich set of client-server tools.

The most widespread use of the CLI standard is as the basis of the ODBC (Open Database Connectivity) specification, which is widely used to allow applications to transparently access database systems from different vendors. The current version of the API, ODBC 3.52, incorporates features from both the ISO and X/Open standards (see below).

[edit] History

The work with the Call Level Interface began in a subcommittee of the US-based SQL Access Group. In 1992, it was initially published and marketed as Microsoft's ODBC API. The CLI specification was submitted as to the ISO and ANSI standards committees in 1993; the standard has the book number ISBN 1-85912-081-4 and the internal document number is C451.

ISO SQL/CLI is an addendum to 1992 SQL standard (SQL-92). It was completed as ISO standard ISO/IEC 9075-3:1995 Information technology -- Database languages -- SQL -- Part 3: Call-Level Interface (SQL/CLI). The current SQL/CLI effort is adding support for SQL3.

In the fourth quarter of 1994, control over the standard was transferred to the X/Open Company, which significantly expanded and updated it. The X/Open CLI interface is a superset of the ISO SQL CLI.

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.