Tin Qian

An agent based architecture for supporting application level security

The heterogeneous nature of distributed systems raises many security issues and concerns. Traditional systems cannot provide customized security policies and mechanisms for heterogeneous applications. Historically, applications have relied on a static security architecture to provide ad-hoc-security guarantees. In this paper we propose a new security architecture based on mobile agents for applications in distributed environments. Our approach allows applications to create and enforce customized policies at run time. These policies and access control requirements can be specified using programs. In addition our framework can handle dynamic requests to change or update these policies and adapt to situational requirements.

Dynamic, distributed, secure multicast in active networks

This paper proposes two frameworks for secure multicast on active networks. The frameworks exploit the computational power of active networks to provide the security desired for multicast, while removing drawbacks in traditional approaches, The main security component in the frameworks is the active capability (AC) which replaces the passive session key. The main advantages of using an AC are lack of an asymmetric key pair requirement for authentication, lack of session key modification requirement when a member leaves the group and a highly distributed and scalable key distribution mechanism independent of availability of a group owner.

Extending OMG Event Service for Integrating Distributed Multimedia Components

Developing multimedia applications, such as video and audio applications, is a difficult task because of the stringent requirement on system resources and the great diversity of multimedia standards and devices. Many existing multimedia systems are monolithic and extremely complex. It is hard to extend and reconfigure those systems. Easy extensibility and reconfigurability is desirable since multimedia research and development is one of the fastest changing fields in computer science. On the other hand, event-based systems seem to be the right solution to these software engineering problems by allowing software integration in a loose and flexible way. Several emerging standards for distributed integrative environments, like the Common Object Request Broker Architecture(CORBA) from the Object Management Group (OMG), have defined standard event service interfaces. However, most existing event services in those systems cannot provide the Quality of Service (QoS) that multimedia applications need. In this paper we address this problem by extending standard OMG event service with temporal factors so that the system can deliver large volume events, like video frames, in real time. A new type of event service called timed event service is proposed and deployed in constructing the high-performance event services. To demonstrate the feasibility of our design, we have prototyped this fast CORBA-compliant event service in the Distributed System Object Model (DSOM).

An integrated architecture for open distributed multimedia computing

Most existing research in the field of distributed multimedia computing is at the level of isolated system components, such as communication and operating system support for multimedia. The application level support for distributed multimedia and continuous media has so far been largely neglected. Little work has yet been carried out on comprehensively integrated platforms that combine authoring, presentation, operating system support and network communications into a cohesive environment for multimedia development. On the other hand the Common Object Request Broker Architecture (CORBA) from the Object Management Group has become a standard for open distributed object systems in the industry. However, CORBA does not take the special requirements of distributed multimedia into consideration. To tackle these problems, we are pursuing an integrative approach of providing general mechanisms for developing open multimedia services in a high speed, telecommunication network environment in an architecture called TOMA. The TOMA CORBA-based architecture provides an open, environment for distributed multimedia applications that combines all aspects of multimedia support. It accomplishes its objectives through the use of an open distributed object model based on CORBA, an adaptive and customizable multimedia operating system, an open rendering environment extended for continuous media, a toolkit for high speed ATM network communications, and a high-level scripting language for composing multimedia objects. In particular, a CORBA-compliant fast event service has been designed and implemented to loosely integrate distributed multimedia components.