Lehrgebiet Informationssysteme

FB Informatik

LG IS

AG DBIS

Staff

Projects

Intern

(C) AG DBIS

STEP-DBS

Computer aided application domains like CAD have high impact on information technology. In addition to powerful hardware software specific aspects like modelling and data manipulation gain more and more importance. Early standards for CAD concentrated on data modelling or data exchange where data exchange was based on data and file formats. Today STEP (Product Data Representation and Exchange, ISO 10303) delivers a powerful tool to handle both aspects on a higher level of abstraction.

With EXPRESS as the object oriented language for data modelling entities of the real world may be neatlessly reproduced. EXPRESS is the very basis for data exchange as it allows for generic (and bidirectional) mapping of data structures because of the given formalism. In the role of a global data model hiding from underlying data models and their heterogenity we talk of STEP databases. Existing database technology may (and must) be used which leads to STEP DBS and features like persistency, consistency, and concurrency.

For encapsulation of used DBMSs we need a uniform access interface which is given in STEP by SDAI (STEP Data Access Interface). SDAI is an application programming interface with bindings to different target languages i.e. C++. SDAI programs may be ported on other STEP DBSs with very little effort; STEP databases become exchangeable.

Mapping of EXPRESS to other data models is well understood but as SDAI is still being standardized, experience here is quite low. We discuss language concepts as well as performance aspects. Because of the great influence of object oriented concepts on STEP object oriented DBMSs are good candidates for implementing STEP DBSs. We study a prototype as well as a commercial realization. In addition we plan to implement SDAI on an object relational system ourselves to show the benefits of descriptive access.