Research On Techniques Of Implementation Of The Standard Data Access Interface Of STEP Based On Relational Databases

In response to distributed and heterogeneous systems and application environments, contemporary enterprises bring forward the better demands for the integration of product information. The techniques of implementation of the standard data access interface of STEP based on relational databases are studied in the dissertation. The uniform accessing of the product information is achieved for the distributed and heterogeneous systems. Used by the techniques, the issues of the product information integration between enterprises or in the interior of enterprises will be resolved in effect.The application of the Contemporary Integrated Manufacturing System(CIMS) and the information management systems of manufacturing encounters the phenomenon of isolation of automatization. Therefore, it is important to research on the techniques of implementation of SDAI of STEP based on relational databases. This document summarizes the constitution of the STEP standard and the object-oriented property of EXPRESS language. The main contents of Standard Data Access Interface(SDAI) is introduced in the paper. And, the issues involving the implemental principle of SDAI in the STEP standard are resolved.The mapping rule from EXPRESS data schema to relational databases schema is studied. The translation of the different semantic data types of EXPRESS into the data definition language of SQL is discussed. The persistency of STEP data in relational databases is realized based on an entity instance manager in working form. The software is developed, which can translate an EXPRESS schema into the SQL statements which generate a relational databases schema for storing STEP data. The software will greatly improve the efficiency of implementation of the STEP standard.The strategy of the SDAI accessing the relational databases based on working form is described in the paper. Based on the strategy, the accessing functions for all entity types for relational databases are developed. Used by the functions, the software can handle the persistency of product data in relational databases. Examples show the validity of the research.Finally, the document summarizes the main fruits of the whole study, and gives the prospects for the tendency of the research.