<- Virtual Exhibitions in Informatics

CSL – A Language for Defining Conceptual Schemas

In the paper „CSL: A Language for Defining Conceptual Schemas“ Breutmann, Falkenberg and Mauer describe a high level data definition language, CSL, for defining conceptual schemas. The language provides descriptive and procedural elements. So static aspects and dynamic behaviour of data can be described with CSL (Conceptual Schema Language).

CSL also provides a general solution to the naming and identification problem and introduces time frames and calendar systems. Conceptual schema constructs can be described completely and explicitly with the Conceptual Schema Language.

CSL provides standard types, object types and association types.

Standard Types and Operations

Standard operations are =, <, >,+, -, *, … and standard types are like INTEGER, REAL, CHAR, STRING, DIGIT

Object Types

Within an object type only those characteristics can be described which hold for all objects of a certain type.

Example:

<self-id object type>::=

OBJECT TYPE <object type name>

{TYPE <standard type>}

{FORMAT <format description>}

{OPERATION <operation list>}

 

OBJECT TYPE CAR TYPE STRING FORMAT LENGTH x = 25

Association Types

The association type definition consists of the unique association type name, the participating object types together with their roles and simple occurrence frequencies and the identifier of the association type together with the candidate identifiers.

Example:

ASSOCIATION TYPE SALARY

OBJECT TYPE PERSON, ROLE HAS-SALARY, OCCURRENCE 1

OBJECT TYPE MONEY, ROLE IS-SALARY, OCCURRENCE 1-20

IDENTIFIER HAS-SALARY

Event-Procedure Constructs

With event-procedure constructs semantic rules can be formulated.

<eventproc>         ::= <procedure head> <procedure body>

<procedure head> ::= {EVENT BEGIN | EVENT END | EVENT MODIFY}

<assoc type name> WITH<parameter list>

<procedure body> ::= BEGIN {<rule part> | NO RULES} END

 

EVENT BEGIN SALARY

WITH PERSON X, MONEY Y

BEGIN

1000 < Y < 20000

END

Reference

Breutmann/Falkenberg/Mauer: CSL: A Language for Defining Conceptual Schema, North Holland Publ.Company, 1979