João Orvalho

Augmented Reliable Multicast CORBA Event Service (ARMS): A QoS-Adaptive Middleware

The CORBA Event Service specification lacks important features in terms of quality of service (QoS) characteristics required by multimedia information. The main objective of the work described in this paper is to augment the standard CORBA Event Service specification with a set of extensions, to turn it into an adaptable QoS middleware multimedia framework. To meet this, some extensions to the CORBA Event Service already developed with the aim of providing multicasting and reliability features have been enhanced in order to allow the close interaction with multicast transport protocols and with QoS monitoring mechanisms. The result was a QoS-aware middleware platform that actively adapts the quality of service required by the applications to the one that is provided by the underlying communication channel. The main quality of service features addressed by the platform - and discussed in the paper - are the support of sessions with different reliability levels, the provision of congestion control mechanisms and the capability to suppress jitter.

Evaluating light-weight reliable multicast protocol extensions to the CORBA event service

The article proposes and evaluates some extensions to the CORBA event service, based on the use of the light-weight reliable multicast protocol (LRMP). These extensions address some limitations of the CORBA Event Service, namely multicasting, reliability and total ordering. The extensions were developed and tested in a prototype environment created for this purpose, and are transparent and fully compatible with the standard OMG event service, enabling the user to decide on the use of standard IIOP or IP multicasting.

State Transmission Mechanisms for a Collaborative Virtual Environment Middleware Platform

Collaborative virtual environments (CVE) require the use of specially designed mechanisms that allow for a consistent sharing of state among involved users. These mechanisms must, somehow, compensate for network latency and losses in such a way that all players have a single, coherent perception of the system state. Common middleware platforms have difficulty in guaranteeing this consistency, and this is the prime reason why the main research topic for CVEs is the efficient, scalable and reliable transmission of state information. This paper presents a state transmission framework developed for a middleware platform that was constructed by the authors in an earlier project [1]. This middleware platform, Augmented Reliable Multicast CORBA Event Service (ARMS), which already supported several QoS adaptation mechanisms and reliable transmission in multicast environments, was extended with CVE-oriented state transmission mechanisms. After an identification of key requirements of collaborative virtual environments, the relevant features of the proposed state transmission framework are presented. This framework has been integrated in the ARMS platform and was subject to a series of performance tests whose results are included and discussed in this paper. The paper ends with a summary of contributions and an identification of guidelines for further work.

A Middleware Architecture for Mobile and Pervasive Large-Scale Augmented Reality Games

Ubiquitous or pervasive computing is a new kind of computing, where specialized elements of hardware and software will have such a high level of deployment that their use will be fully integrated with the environment. Augmented reality extends reality with virtual elements but tries to place the computer in a relatively unobtrusive, assistive role. Specialized network middleware solutions for large scale mobile and pervasive augmented reality games are, to our knowledge, inexistent. The work presented in this paper focuses on the creation of such type of network middleware for mobile and pervasive entertainment, applied to the area of large scale augmented reality games. In this paper we describe the architecture of the system, which works over a 3GPP network. The paper presents architectural and implementation aspects, along with evaluation results. The results show that the proposed solution is able to cope with the stringiest requirements of augmented reality systems.

Security and privacy in a middleware for large scale mobile and pervasive augmented reality

Ubiquitous or pervasive computing is a new kind of computing, where specialized elements of hardware and software will have such high level of deployment that their use will be fully integrated with the environment. Augmented reality extends reality with virtual elements but tries to place the computer in a relatively unobtrusive, assistive role. In this paper we propose, test and analyse a security and privacy architecture for a previously proposed middleware architecture for mobile and pervasive large scale augmented reality games, which is the main contribution of this paper. The results show that the security features proposed in the scope of this work do not affect the overall performance of the system.

Middleware for Embedded Sensors and Actuators in Mobile Pervasive Augmented Reality

In this paper we describe a Java middleware, the SENSACT API, which enables the construction - and connection through a Bluetooth network - of a network of sensors and actuators for the purpose of enabling its use in mobile pervasive augmented reality games. The system enables sensors and actuators to be deployed and subsequently connected to a central coordinating device, the game device, that has a compatible middleware API, the Status Transmission Framework Version 2.0 PAN API. The presented middleware package was subject to functional as well as performance tests using Sun Microsystems Java Wireless Toolkit 2.3 Beta version, which showed that the proposed API is adequate for small sensor/actuator networks.

A Platform for the Study of Reliable Multicasting Extensions to CORBA Event Service

Conference applications play a key role in workgroup tools, and provide an excellent environment for the development and evaluation of proposals concerning multicasting and reliable communications. A nuclear aspect of conference applications is their ability to use multipoint communication in heterogeneous environments. In the scope this work, a platform that uses several extensions to the CORBA Event Service was developed. This platform is based on ITU T.120 recommendations, and supports reliable multicasting communication for both data and control information. The control information is managed by a service implemented in Java™, according to the CORBA Event Service model. The present paper introduces and discusses the main features of the proposed platform. Also, provides a general description of the conference framework architecture that was built on the platform, with some emphasis on reliable multicasting communication and on system synchronism. In the final part of the paper, the specification and the implementation of the proposed extensions to the CORBA Event Service are presented.

Sixrm: Full Mesh Reliable Source Ordered Multicast

In this paper we describe Sixrm, a reliable multicast protocol that supports multiple sources that are at the same time multiple destinations and that works both on ipv4 and on ipv6. The protocol is completely configurable by profile settings and is implemented completely in Java Standard Edition 1.5. The protocol is included on the distributed server part of network middleware for large scale mobile and pervasive augmented reality that we also introduce in this paper, and supports the ordering of messages by source without duplicates and its reliable delivery to the application, without the support of network elements

Large Scale Mobile and Pervasive Augmented Reality Games

Ubiquitous or pervasive computing is a new kind of computing, where specialized elements of hardware and software will have such high level of deployment that their use will be fully integrated with the environment. Augmented reality extends reality with virtual elements but tries to place the computer in a relatively unobtrusive, assistive role. To our knowledge, there is no specialized network middleware solution for large-scale mobile and pervasive augmented reality games. We present a work that focus on the creation of such network middleware for mobile and pervasive entertainment, applied to the area of large scale augmented reality games. In, this context, mechanisms are being studied, proposed and evaluated to deal with issues such as scalability, multimedia data heterogeneity, data distribution and replication, consistency, security, geospatial location and orientation, mobility, quality of service, management of networks and services, discovery, ad-hoc networking and dynamic configuration

Extension to CORBA event service for a conference control system

Conferencing applications require an efficient conference control service. This paper introduces the main features of a conference control service based on the CORBA event service using the Java platform, under development at the Communications and Telematic Services Group of the University of Coimbra. This framework is based on the ITU T.120 recommendations, with reliable multicasting communication for both data and control information. The control service extends the CORBA Event Service architecture with mechanisms for reliable IP multicast communication, with total ordering of the events transmission, filtering and fragmenting/reassembling of large messages.