Lia Goldstein Golendziner

Extending a structured document model with version control

The paper presents an approach to extend a structured document model with version control. It discusses how the characteristics of the version model used (L.G. Golendziner and C.S. Santos, 1995) fulfil the requirements of a document management application which handles structured documents. A very useful functionality supported is that documents can be managed using the current or specific versions of their components, thus allowing the user to define different strategies to keep the document history. The proposed approach also includes a notification mechanism to address the problem of keeping the references consistent when shared documents are used. The application is the GDOC document management system, which implements an innovative data model for storing documents in a relational database and handles them in an intranet.

Modelling an Engineering Design Application Using Extended Object-Oriented Concepts

This paper presents an approach to extend objectoriented data models, in which versions of an object are allowed to appear at dtyferent levels of an inheritance hierarchy, in contrast to the known approaches where they are admitted only at one level. This approach allows the design and instantiation of objects to become very natural, starting with the design of an object in a class and refining it, adding properties to the subclasses. Versions of objects can be defined in a subclass, having ascendant versions/objects associated to the superclasses. The paper also discusses how the extended model can be used to model engineering applications, fulfilling their requirements. The application is the STAR framework, which implements an innovative and flexible data model that allows the user to define an object schema for each design object. Design alternatives and views can be created during the design process and are represented in the object schema. Versioning appears in the STAR model not only for the real design data, but also for alternatives and views in the object schema. This requirement is not naturally modeled by the existing version models in object-oriented databases.

Schema Evolution in the STAR Framework

The STAR data model supports the definition of object schemata, according either to some design methodology or to the designer’s decision. Object schemata allow a flexible management of the various representations that are created during the design of a particular object. Object schemata can evolve or even be dynamically defined, departing from an existing object schema and making changes to it. Schema evolution facilities are a valuable support for both the definition of new design objects and design methodology management. Schema evolution is maintained through versions, so that version management is applied not only to design objects themselves, but also to object schemata. Consistency is guaranteed for schema operations, based on a set of invariant rules.

Configuration Management in the STAR Framework

Configuration management is an essential service to be provided by electronic design automation frameworks. Besides conventional static and dynamic configurations, normally offered by most systems, the STAR framework supports specialized facilities, such as open configurations (as in VHDL), the automatic resolution of open and dynamic configuration through expressions on object properties, and the manual resolution of these configurations by means of a graphical-interactive database browser. Unlike other systems, the STAR configuration manager is a separate framework module which the final user can directly reach through the main user interface. Furthermore, the STAR configuration management mechanisms respond to novel requirements, imposed by powerful versioning services.

The Visual Interface of the STAR Framework

Visual data management employed in EDA Frameworks helps in many design tasks, offering various facilities, specially related to the formulation of queries. In the STAR framework, a visual interface is the primary user interface to the system, allowing access to different managers and offering facilities for browsing and querying design objects. A graphical browser is available, allowing the navigation through design objects stored in the database, such that object properties can be shown and related objects can be investigated, departing from a selected one. Graphical queries can be formulated in an interactive way. Complex queries can be formulated via a textual SQL-like query language, extended with facilities for version manipulation and navigation in the inheritance hierarchy defined by the STAR data model.

Versions in the context of object-oriented database systems

This paper proposes an integration of the version concept with the abstraction concepts present in object-oriented database models, considering structural aspects. The possible relationships between objects (and versions) and their ascendents in the class or type hierarchies is discussed and a discipline for version creation is proposed, based on the object constructors used to build the versions.