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Table of Contents:

Definition and Overview

1. Benefits of a Specification Language

2. History

3. SDL Characteristics

4. Theoretical Model and Structure

5. Sharing Information, Reuse, and Maintenance

6. Openness, Portability, Scalability, and Distributed Applications Openness

7. Graphical and Textual Notations and Application Areas

Self-Test

Glossary

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Sharing Information—Packages

SDL packages are graphical SDL libraries that define data structures, signals, process types, block types, and system types that can be shared between SDL systems and projects. This facilitates maintenance and reuse aspects for large applications and allows for sharing information between many systems.

Reuse and Maintenance (Specialized Inheritance and Polymorphism)

Apart from supporting object-oriented data (i.e., object-oriented passive objects) SDL also supports all object-oriented features for active objects–for example, systems, blocks, and state machines down to the transition level. This extends the traditional passive class concept that is more oriented towards nontechnical applications and is found in UML, OMT, C++, and Java. SDL specializes it for technical applications (i.e., real-time systems, distributed systems, and event-driven systems, where there is a heavier focus on communication and active state-oriented objects).