Christine Collet

Composite Events in NAOS

This paper deals with composite events in active databases. It describes the syntax and semantics of NAOS composite event expressions. This semantics is based on the semantics of the proposed operators and on the notions of context of detection and validity interval These notions are central especially for event types containing negations and strict disjunctions. The paper also describes the event detection process with is modelized by event graphs.

Denotational Semantics for an Active Rule Execution Model

In the last few years, many active database models have been proposed. Some of them have been implemented as research prototypes. The use and study of these prototypes shows that it is difficult to get a clear idea of the proposed approaches and to compare them. More generally there are some unquestionable difficulties in understanding, reasoning about and teaching behavior of active database systems. We think there is a need for formal descriptions of the semantics of such systems in order to describe and to understand them with less ambiguities, to compare them and to come up with some progress in defining standard concepts and functionalities for active databases.

Defining and Coordinating Open-Services Using Workflows

Recently, workflow technology has been widely accepted as a mean for integrating services to build applications (services). Provided a set of services a workflow is used to coordinate and to synchronize their executions. This paper proposes an approach based on workflow technology and an associated mechanism for defining and coordinating services. Given a service provider that exports a set of methods a workflow can be defined for coordinating calls to such methods, in order to program a service. A service definition is decoupled from the capabilities of the service provider, thus a service may be adapted according to different application requirements. Services coordination is carried out by an orchestrator workflow that provides a fine control on their executions. Definition and coordination are characterized by a set of properties that ensure the correct behaviour of the resulting application (service).

Pyros - an environment for building and orchestrating open services

Service oriented computing has gained a considerable momentum as a new paradigm for building enterprise information systems. Notable efforts have been made recently from both researchers and industrials to support the construction of service-based applications; nevertheless several issues still need to be tackled including service definition and adaptation, and services orchestration. This work proposes Pyros, an environment for building and orchestrating open services. An open service is represented by a workflow that coordinates calls to service provider methods. Thereby component activities and the way they are synchronized are rendered visible. In order to finely orchestrate services, they are associated with entry points. An entry point acts as a gateway for inserting and getting information about the progress of service execution. The paper details the approach adopted by Pyros for building and orchestrating services, and presents associated architectural choices. Furthermore, it reports an experimentation that we conducted for implementing an eTrader application using Pyros.

Integrated Tools for Object Oriented Persistent Application Development

This paper presents the main characteristics of an integrated environment for object oriented, persistent application development. We first discuss the rationale of our approach and give our analysis of current database systems or persistent languages. Using such systems or languages is still a very difficult task because persistent application development combines the complexity of database schema design together with a software engineering problem.

A component-based infrastructure for customized persistent object management

This paper introduces a component-based infrastructure to build customized persistent object managers. The usage of such an infrastructure is twofold. First, the infrastructure can be used to instantiate persistence object managers for applications where full-fledged database management systems (DBMS) may be cumbersome (e.g. resource constrained systems). Second, it can be used to build database middleware. We focus on the description of components and related design patterns.

Towards a Semantic Event Service for Distributed Active Database Applications

This paper proposes an approach to building event services for active database applications. It introduces dimensions to characterize distributed event definition, detection, production and notification. The core of our approach is a parametric event service called QUETZAL that has three interfaces, each of them implementing the given dimensions as parameters. Therefore, different event (detection) models may be defined simply by giving values to these parameters. Such an approach provides flexible definition, detection, production and notification of events according to application needs. Since our service is based on a consumer-producer principle, it can be combined with any producer and consumer, facilitating in this way communication and collaboration between distributed components such as classical applications, database transactions, primitive event detectors or event notification tools.

The NAOS system

It is now recognized that integrating a production rule facility into a database system provides a powerful mechanism for designing or implementing several features. The Native Active Object System(NAOS)[l] incorporates an active behavior within the object-oriented database management system 02 [2]. It has been developed for the GOODSTEP platforml [3] dedicated to support the construction of customized Software Development Environments (SDE) with different tools.

Building information systems by orchestrating open services

Service oriented computing has gained a considerable momentum as a new paradigm for building enterprise information systems. Notable efforts have been made recently from both researchers and industrials to support the construction of service-based applications, nevertheless several issues still need to be tackled including service definition and adaptation, and services orchestration. This work proposes an approach for building and finely orchestrating open and adaptable services. An open service is represented by a workflow that coordinates calls to service provider methods. Thereby component activities and the way they are synchronized are rendered visible. Service adaptability refers to the possibility to modify an open service. Through adaptation operations a service can be customized according to given user (application) requirements. In order to finely orchestrate services, they are associated with entry points. An entry point acts as a gateway for inserting and getting information about the progress of service execution. Defined services and orchestration are verified to ensure a correct behaviour of the resulting application. The paper details our approach for building and orchestrating services, and presents associated architectural choices.

The VIRTUOSE distributed object store

The efficiency of the object store of an object-oriented database management system strongly depends on the way in which memory and distribution management aspects are considered. Such aspects include addressing, concurrency control management, distribution management and cache management. The Arias distributed-shared-memory systems characteristics provides an interesting framework for those aspects and for building scalable applications. This paper shows how we used the Arias system for designing and implementing the VIRTUOSE (VIRTual Object StorE) distributed object store.