Juan Quemada

TIC: A timed calculus

TIC is a timed algebraic calculus which combines ideas from asynchronous and synchronous calculi. Time is introduced by assigning explicit time restrictions to the events of an asynchronous calculus. The semantics is defined in an operational way. Interleaving of behaviours is defined in such a way that a proper merge of events in time is achieved. Weak timed bisimulation is also defined. Examples are presented to show the applicability of the calculus to the study of timed behaviours.

State exploration by transformation with LOLA

LOTOS is a Formal Description Technique developed within ISO to specify services and protocols. This paper describes a tool for doing LOTOS to LOTOS transformations. It has applications in state exploration, deadlock detection, testing, validation and in design by stepwise refinement. The transformations are: expansion (transformation of parallelism into summation and prefix); parameterized expansion; i action removal. The transformations obtain LOTOS specifications which relate to the original one through strong (expansion and parameterized expansion) or weak (i-action removal) bisimulation congruence.

VaaS: Videoconference as a service

Internet is a place nowadays where interoperating services are offered which can be integrated or mashed up in order to fulfill user demands. This paper proposes a way to offer videoconference as a Web service over an interface which can be used by third parties to enrich their applications. This interface includes a security mechanism supporting delegated authorization to allow integration into third partys environments. Via this interface virtual rooms are provided where users can collaborate with audio, video, shared applications, IM, etc. An implementation of these concepts is described, including performance figures and validation results. We would finally like to stress that this architecture has been defined to support a scalable cloud computing service over the Internet.

ISABEL: A CSCW Application for the Distribution of Events

Introduction Many activities which in the past have required physical presence and direct interaction among participants can be performed in a distributed fashion with the help of advanced information technologies such as, CSCW [1,2] (Computer Supported Cooperative Work), interactive multimedia services and broadband communications. Technologies aiming at supporting the collaboration among individuals or groups are identified under the term groupware technologies. Asynchronous interactions which do not require physical presence of interacting persons have matured during the last years. Very successful examples of asynchronous groupware exist. LOTUS Notes [3] is considered probably the most successful commercial product in this area. The Internet and many of its application can be considered as groupware technologies to some extend. Technology can support today also synchronous interaction where real time contact among individuals is required. We mean by synchronous interaction the exchange of verbal, visual, ... messages or information, like the exchanges of information carried out typicaly in meetings, conversations or other activities where several participants collaborate in physical presence. Remote synchronous interaction is not new, the plain old telephone is a very good example of an old technology supporting a simple but very effective form of synchronous interaction. POTS is today by far the most demanded synchronous service. This service has evolved into N to N audioconference or videoconference facilities. Computers in general and the Internet have also had primitive types of character oriented synchronous interactive services for a long time, like TALK, IRC, ... Today low quality voice and video over the Internet is also common practice with applications like, CU-SeeMe, IVS, VAT, ... Audiovisual broadcasting is also a highly demanded type of remote synchronous interaction which has been done since many years. Although broadcasting has really no interaction because the flow of information is unidirectional, it is nevertheless being addressed in the experiments performed for creating new synchronous services. One of the most popular services on the multicast backbone of the Internet, also known as the MBONE, is the conference broadcasting for which a Session Directory (SD) exists where the list of broadcast conferences is displayed in real time. Sophisticated forms of remote synchronous interaction requiring good quality telepresence demand more bandwidth and more reliable communications to achieve a proper interaction. Therefore for setting up large sacle experiments like the RACE/ACTS Summer Schools [2,5,6,9] a complex collaboration among a large number of organizations has been needed. In addition, the availability of large …

Isabel: an application for real time collaboration with a flexible floor control

Isabel is a P2P like multipoint group collaboration tool for the Internet, which implements an innovative service concept for synchronous collaborations based on a flexible and programmable floor control. This approach leads to a more natural and effective management of collaboration sessions. The flexible and programmable floor control incorporates the experience gained in many years of service trials with real users in distributed conferences, classrooms or meetings. The main conclusion after all those trials is that services should use more or less the same media components (audio, video or application sharing), but differ in the floor control model used. The flexible floor control is especially well suited for multipoint audience interconnection in distributed classrooms, conferences, meetings, etc. The development of Isabel started in 1993 for the distribution of the RACE Summer Schools on Advanced Broadband Communication (ABC93-6) where the early versions of this service concept were developed and tuned. The effectiveness of the Isabel service concept has been proven and enhanced since then in many other distributed events, such as Global360x, IDC9x, Global IPv6 Summitts, Telecom I+D, etc. The adaptation of Isabel to the broadband Internet (including VPNs, IPv4/IPv6 transition scenarios, mixtures of unicast and multicast) has reached maturity recently

ISABEL - Experiment Distributed Cooperative Work Application over Broadband Networks

Users are looking towards ATM technology as a suitable solution for specific applications in the new field of distributed multimedia. The aim of ISABEL is to take benefit of the new broadband technology in order to provide a good access to new distributed multimedia facilities. The application has been developed to cover two main fields: distance learning activities between two or more real conference rooms and a flexible framework to configure many different computer support cooperative work (CSCW) scenarios. The paper describes the functionality of ISABEL and its use to support real experiments.

Educanext: a framework for sharing live educational resources with isabel

EducaNext is an educational mediator created within the UNIVERSAL IST Project which supports both, the exchange of reusable educational materials based on open standards, as well as the collaboration of educators over the network in the realization of educational activities. The Isabel CSCW application is a group collaboration tool for the Internet supporting audience interconnection over the network, such as distributed classrooms, conferences or meetings. This paper describes the conclusions and feedback obtained from the integration of Isabel into EducaNext, its use for the realization of collaborative educational activities involving distributed classrooms, lectures or workshops, as well as the general conclusions obtained about the integration of synchronous collaboration applications into educational mediators.

Improving LOM-Based Interoperability of Learning Repositories

This paper analyses the use of LOM Application Profiles for learning object repository interoperability. Based on an exemplifying use case the paper presents a case study, which aims at developing a LOM Application Profile to realized Smart Spaces for Learning. Finally, a schema is designed which selects the necessary LOM elements and makes a LOM-conformant extension to represent usage conditions and learning activities. This work is part of the Elena project, which focuses on integrating advanced educational mediators in a network of federated services.

The Lotosphere Design Methodology

This chapter provides an application oriented description of the LOTOS Design Methodology produced in the Lotosphere project. This design methodology is a formally based stepwise refinement approach to system design, conceived to give formal support to an industrial design process, in order to achieve high quality designs.

Joint Degrees in E-Learning Systems: A Web Services Approach

In order to allow the development of joint degrees through heterogeneous e-learning systems, we propose a federation services architecture whose implementation will be based on Web services. Our main objective is to allow e-learning systems to be able to work in a collaborative way; combining their data and functionality through the integration of their services. These services will be combined and federated, according to collaboration agreements between Universities. Joint degrees through e-learning systems will allow the development of new joint curricula and the participation in the convergence of higher education