A file interface and data dictionary for the ECRDBS high level database system

The Entity-Category-Relationship (ECR) data model captures important descriptive semantics of a database, such as generalization hierarchies and attribute inheritance. Since no complete ECR DBMS has been implemented before, an ECR DBMS, called ECRDBS, is implemented to demonstrate the usefulness of the above data modeling concepts. This thesis describes the design and implementation of two components of ECRDBS; the file interface and the data dictionary system. In the first part of the thesis, the indexed file organization on the VAX/VMS system is used to implement a file interface which provides basic, record at a time, file commands for storage, retrieval and updating of information. In the second part of the thesis, a data dictionary system based on the ECR model is implemented. It is responsible for parsing the data definition statements for a particular database and creation of data dictionary files. Function procedures are provided for the user and other components of the ECRDBS system to access the information stored in the data dictionary files.