Object Histories as a Foundation for an Active OODB

Several links exist between active and temporal databases. These are summarised by the observation that rules are triggered by a specified evolution of the database. In this paper, we discuss the relation between active and temporal database using DEGAS, an object-based active database programming language. To achieve full active database functionality, a DEGAS object records its complete history. Hence, all data needed for a temporal database supporting a single temporal dimension is provided. Furthermore, the semantics of the active behaviour of DEGAS are defined straightforwardly in terms of the object history. Finally, we discuss the advantages and disadvantages of extending DEGAS with a second time dimension (to achieve full temporal functionality) from an active database perspective

HOOD : a Higher-Order Object-Oriented Database model and its implementation

Bibliography: pages 133-140.There is no accepted standard for the object-oriented database paradigm at present, which has led to different definitions of features and conformance requirements. HOOD is a Higher-Order Object-Oriented Database system which defines a meta-data model for specifying the requirements of an Object-Oriented Database, which provides uniformity and extensibility. From this specification and by making use of a comprehensive structure system, an exemplar or implementation model is defined. Among the constructs provided by the model are types, instances, objects, values, methods, base types, generic types and metatypes. The mechanisms of instantiation and subtyping allow for relationships between these constructs. Extensibility is provided in the model for types, base types, structures and methods. Uniformity is achieved by defining all constructs as instances and through the use of messages for all operations. There is only one form of object construct which provides persistence and identities. The complex values and extensibility of the model allow it to adapt in order to model the real world instead of adapting the real world to fit the model. We have implemented a subset of the structures and values defined in the model, provided persistence and identities for object, and included the various constructs mentioned above. The method language allows for the specification of methods, the passing of messages, and the use of complex values. The compiler performs type checking and resolution and generates instructions for an abstract machine which manipulates the database

Designing active objects in DEGAS

This report discusses application design for active databases, in particular for the active object-based database programming language DEGAS. In DEGAS one modularisation principle, the object, is applied to all elements of the application, including rules. We discuss a design process consisting of four phases, corresponding with the four kinds of capabilities in a DEGAS object, attributes, methods, rules, lifecycles. The elements of this design process are similar to those found in a design methodology such as OMT. To illustrate the design process we use the example of workflow management. In addition, it shows that the application of one modularisation to all elements of an active database leads to a clear modularisation of the workflow application, Furthermore, this modularisation facilitates all important workflow evolutions

Application development in a knowledge-based conceptual generator

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.Includes bibliographical references (leaves 170-175).by Johanes Chandra Sugiono.M.S