CARP@ - Managing Dynamic Distributed Jini Systems (presentation)
Fahrmair, M., Salzmann, C. and Schoenmakers, M.
    Jini offers the basic technology to develop distributed systems where the participating clients, services and their interactions can adapt dynamically to a changing availability and configuration of the network.Jini can be seen as an dynamic middleware layer on top of the distribution middleware.
    The tool Carp@ (implemented itself as a Jini system) is designed to visualize, analyze and control dynamic and distributed Jini systems. Unlike usual Jini browsers Carp@ allows the observation of services and clients, their interconnections and the messages exchanged between them.  The tool extracts an architecural component model based on components, ports and connectors.  Based on this model the structure within the dynamic middleware layer should be changeable at runtime without changing the code, for example for load balancing.This paper describes the tool and its intended usage and the work in progress.
Download the paper in PDF format.

X2TS: Unbundling Active Object Systems (presentation)
Liebig, C. , Malva, M. and Buchmann, A.
    Workflow Management Systems exhibit task management and coordination functionality at the application level. Separating coordination of activities from their realization is the basis for a flexible and extensible software architecture for workflow management applications. We are interested in applying concepts of workflow management to distributed object systems, CORBA in particular, where the business logic of applications is implemented by composed objects. Our research is motivated by the requirements of a concrete application, an Integrated Tower System (ITS) that is part of the new German Air Traffic Control System (ATC). The ATC-ITS has workflow-like requirements and shall be built in a component-oriented manner on a CORBA platform. A primary requirement is to ensure reliable execution and provide support for rich failure semantics and exception handling, like compensation and contingency actions. As part of the ongoing research we are investigating how to incorporate advanced transaction management in CORBA by unbundling concepts of active DBMSs and how to integrate those concepts with the CORBA Object Transaction Service and a notification service. The resulting service implements an event-action model with transactional behavior and rich coupling modes and is used as a basic building block for reliable components.
Download the paper in PDF format.

Session Models for Multicasting Environments (presentation)
Hesselman, C. and Eertink, H.
    We describe the foundations of a middleware-based system that controls the QoS of multimedia multiparty applications. The system is geared toward an heterogeneous operating environment that consists of fixed and mobile terminals and networks with widely varying capabilities in terms of media devices, codec support, available network capacity, and so on. The system deals with this heterogeneity by grouping together those parts of an application that operate in an environment with similar capabilities. Each group forms a relatively homogeneous set of application parts that are interconnected by a multicast session. As a result, the system can keep active QoS control within each multicast session to a minimum and can focus on the place where active QoS control is required, i.e. between multicast sessions. We argue that this approach delivers a sufficient QoS while it at the same time ensures a high degree of scalability. The system interconnects the homogeneous multicast sessions through proxies that are responsible for bridging QoS differences. Our system focuses on the dynamic establishment and configuration of structures of multicast sessions and proxies, in particular on the role of capability negotiation and the consequences of terminal mobility.
Download the paper in PDF format.

Continuum: A Flexible Java Middleware for Building Large-Scale Virtual Environments on the Internet (presentation)
Dang Tran, F. and Gerodolle, A.
    The Continuum platform, presented in this paper, aims to offer an object-oriented software framework for building large-scale networked virtual environments on the Internet with a particular interest toward real-time distributed simulation and online game applications. Classical techniques employed in distributed object-oriented databases being generally not compatible with the real-time constraints of these applications,  the proposed platform is architectured as an open and extensible software framework which can be specialized on a per-application basis and which can take into account closely the application semantics  following a design approach similar to the one of Application Level Framing for communication protocols. The proposed architecture is server-less and relies on a partial replication model in which the whole logical simulation space is partially replicated over a set of  individual simulations based on perception-based criteria: each simulation object is associated with an aura which quantifies it capacity to perceive and influence its environment. Consistency and synchronization between replicas is handled on a per-object basis through an event-based communication framework.  The Continuum framework has been developed 100% in Java and has been integrated with the open-source Java ORB Jonathan. Experiments and extensions are currently under way to support  large-scale persistent simulated environments populated by  several thousands of objects.
Download the paper in PDF format.

Optimizing the CORBA Component Model for High-Performance and Real-Time Applications (presentation)
Wang, N. , Schmidt, D.C. and Levine, D.
    With the recent adoption of the CORBA component model (CCM), application programmers now have a standard way to implement, manage, configure, and deploy components that implement and integrate CORBA services.  The CCM standard not only enables greater software reuse for servers, it also provides greater flexibility for dynamic configuration of CORBA applications.  Thus, CCM appears to be well-suited for general-purpose client/server applica-tions.
    Due to the complexity of the standard and relative immaturity of implementations, however, CCM is not yet appropriate for mission-critical applications with high-performance and real-time quality of service (QoS) requirements. There-fore, we have begun a project to identify, prototype, benchmark, optimize, and deploy the key patterns and framework components necessary to mature the CCM standard so it can be applied successfully to mission-critical applications with stringent QoS requirements. In particular, we believe that the CCM provides an effective model for configuring various QoS aspects, such as transport protocols, memory and bandwidth management, concurrency, dependability, and security, into standard reusable components and adaptively controlling them.
    There are two contributions of our research project. First, we are identifying the performance bottlenecks and other obstacles that impede the use of CCM for high-performance and real-time applications. Second, we are demonstrating the effectiveness of our methodology of applying optimization principle patterns to alleviate these obstacles.
Download the paper in PDF format.

Effortless Software Interoperability with Jini
Benchiao Jai, Michael Ogg, Aleta Ricciardi
    We describe how, and how easy it is, to achieve interoperability between software components by using Sun's Jini distributed object technology for the core platform and services.  We then describe how to "Jini-fy" general black-box (i.e. legacy, third-party, or proprietary) software components, and those written to the CORBA standard, or with other distributed object technologies.
Contact the authors for paper.

S-agent: The Design of Secure Mobile Agent System (presentation)
Satoshi Makino , Tadashi Okoshi, Jin Nakazawa and Hideyuki Tokuda
Graduate School of Media and Governance, Keio University, Japan
This paper proposes a secure mobile agent system s-agent.   There exists a wide range of security issues in using mobile agents.  We categorized the attacks against mobile agent security into three: attacks by hosts against agents, ones by agents against hosts and ones between agents.  s-agent system provides an architecture which covers these three categories of attacks.  Existing researches solve some parts of the prob-lems, leaving the others still unsolved.  For the agents to be widely used, as many problems as possible must be solved. This system is distinctive in its inter-agent access control.  Modification detection and DoS-attack-resistant security manager are also featured.
Download the paper in PDF format.

Architectural Requirements for the Effective Support of Adaptive Mobile Applications (presentation)
Efstratiou, C., Cheverst, K, Davies, N. and Friday, A.
    Mobile applications are required to operate in environments that change.  Specifically, the availability of resources and services may change significantly during typical system operation.  As a consequence, mobile applications need to be capable of adapting to these changes to ensure they offer the best possible level of service to the user. Our experiences of developing adaptive applications have led us to believe that existing middleware fails to provide the necessary support for such applications. Moreover, we believe that current research in this area is also failing to address the core requirements of adaptive mobile systems. In this paper we present a set of requirements for future mobile middleware which have been derived by considering the shortcomings of existing approaches and the needs of application developers.  Key among these requirements is the need to support coordinated action between application and system components and the resolution of conflicts caused by the need to adapt to multiple contextual triggers. The paper concludes with the presentation of an architectural framework within which middleware researchers can deploy solutions to the problems identified.
Download the paper in PDF format.