Dipayan Gangopadhyay

Contracts: specifying behavioral compositions in object-oriented systems

Behavioral compositions, groups of interdependent objects cooperating to accomplish tasks, are an important feature of object-oriented systems. This paper introduces Contracts, a new technique for specifying behavioral compositions and the obligations on participating objects. Refinement and composition of contracts allows for the creation of large grain abstractions based on behavior, orthogonal to those provided by existing class constructs. Using contracts thus provides a basis and vocabulary for Interaction-Oriented design which greatly facilitates the early identification, abstraction and reuse of patterns of behavior in programs. Contracts differ from previous work in that they capture explicitly and abstractly the behavioral dependencies amongst cooperating objects. By explicitly stating these dependencies, contract also provide an effective aid for program understanding and reuse.

M(DM): an open framework for interoperation of multimodel multidatabase systems

The authors present M(DM), an extensible metalevel system in which the syntax and the semantics of data models, schemas, and databases can be uniformly represented. M(DM) consists primarily of a set of metatypes that capture and express data-model constructs in second-order logic: a data model is represented as a collection of M(DM) metatypes. To achieve extensibility, M(DM)s metatypes are organized into an inheritance lattice. The robustness and openness of the approach are demonstrated by expressing a variety of data models in M(DM), and the authors show how to exploit M(DM)s metalevel capabilities for hiding representational heterogeneities in multimodel multidatabase systems.<<ETX>>

Understanding frameworks by exploration of exemplars

A framework is designed to cover a family of applications or subsystems in a given domain and is typically delivered as a collection of interdependent abstract classes, together with their concrete subclasses. The abstract classes and their interdependencies describe the architecture of the framework. Developing a new application reusing classes of a framework requires a thorough understanding of the framework architecture. We introduce the notion of an exemplar for documenting framework, and propose exploration of exemplars as a means for architecture understanding. An exemplar is a executable visual model consisting of instances of concrete classes together with explicit representation of their collaborations. For each abstract class in the framework, at least one of its concrete subclasses must be instantiated in the exemplar. Model level exploration of exemplars is unique among the prevalent approaches to framework based development; existing approaches still emphasize different class browsing and retrieval technologies, active cookbooks, or code tracing.<<ETX>>

OOLP: A Translation Approach to Object-Oriented Logic Programming.

OOLP integrates the superior modeling capabilities of object-oriented paradigm in the declarative framework of logic programming. Method invocation in OOLP is given a precise model theoretic semantics which is consistent with that of logic programming. OOLP is extended to a practical object-oriented database language OOLP+ by adding some extra-logical features. OOLP+ allows object identity, multiple inheritance, method overriding and dynamic updating among other features. OOLP+ is implemented by translating it to Prolog. The translated programs executes without metainterpretation. This allows the use of all Prolog or Datalog optimization techniques. In this respect OOLP+ is unique among alternative proposals presented in the literature.

ObjChart: Tangible Specification of Reactive Object Behavior

ObjChart is a new visual formalism to specify objects and their reactive behavior. A system is specified as a collection of asynchronously communicating objects arranged in a part-of hierarchy, where the reactive behavior of each object is described by a finite state machine. Value propagation is effected using functional invariants over attributes of objects. A compositional semantics for concurrent object behavior is sketched using the equational framework of Misra.In contrast to other Object Oriented modeling notations, ObjChart uses object decomposition as the single refinement paradigm, maintains orthogonality between control flow and value propagation, introduces Sequence object which embodies structural induction, and allows tracing causality chains in time linear in the size of the system. ObjCharts minimality of notations and precise semantics make ObjChart models of systems coherent and executable.

Design by Framework Completion

An object-oriented framework in essence defines an architecture for a family of applications or subsystems in a given domain. Every application in the family obeys these architectural restrictions. Such frameworks are typically delivered as collections of inter-dependent abstract classes, together with their concrete subclasses. The abstract classes and their interdependencies implicitly realize the architecture. Developing a new application reusing classes of a framework requires a thorough understanding of the framework architecture.

An open framework for federating integrated management model of distributed it environment

Heterogeneity has been the curse of the IT industry and systems management is no exception. As organizations are expanding their global business, and new technology and platforms are being introduced, the complexity of systems management is increasing rapidly due to heterogeneity and getting unified view of IT environments is becoming more difficult. To simplify and expedite information integration, this paper brings best practices of model-driven system and information integration to the problems of information integration in systems management. Specifically, we present an open framework for describing meta-model of a new component in isolation using UML and relating it with meta-models of other components through semantic relationships. The resulting integrated meta-model together with querying mechanisms for various sources can federate automatically and on-demand, integrated model of IT environment without relying on a central database repository.

Framework-centered software development: report on the workshop

The workshop found broad interest in the 00 community and significant contributions were submitted. There were two groups of submissions: one for framework design and the other for framework adaptation. There were oral presentations of 2 papers selected from each category, followed by groupdiscussions in the afternoon. The rest of this report includes abstracts of the presentations (including links the sources), and the findings from the discussion sessions. We conclude the report with a list of topics where more research will be fruitful.