A semantic object-oriented data access system

摘要

Lack of support for Entity-Relationship (E-R) semantics and the disconnect between object-oriented programming languages (OOPLs) and database languages remain key roadblocks to the effective use of object-orientation in information systems development. We present SOODAS, a Semantic Object-Oriented Data Access System that defines and manages the meta-data necessary to support E-R semantics and set level querying and provides related interface generation tools. SOODAS consists of five meta-classes. DomainObject and Relationship provide the capabilities needed to define and manage entities, attributes, relationships, external identifiers, and constraints. Together with the meta-class QueryNode, DomainObject provides an object-oriented, multi-entity querying capability. Queries can be arbitrarily complex and can include cycles and transitive closure. Persistence is provided by the meta-class, PermanentObject, of which DomainObject and Relationship are subclasses. The meta-class, DomainObjectInterface uses the meta-data in DomainObject and Relationship to generate a standard, re-usable interface for displaying and maintaining instances of any entity. Since SOODAS is implemented entirely in Smalltalk, it can be seamlessly integrated with any Smalltalk application.