Joaquim Arnaldo Martins

ARQ protocols with adaptive block size perform better over a wide range of bit error rates

The throughput of conventional automatic-repeat-request (ARQ) protocols, such as the stop-and-wait, go-back-N, and selective repeat, can be improved by dynamically adapting the protocol block length so that it approaches the optimum value for varying channel bit error rates. A very simple algorithm to implement such an adaptive scheme is presented. The algorithm assumes a known block error rate, estimates the bit error rate, and determines the best block length. Results of a simulation study show that in spite of its simplicity, the algorithm performs well. >

PC workstation for Ethernet monitoring and management

The authors present a monitoring and management workstation for IEEE 802.3 networks (Ethernet) based on a PC-AT. The monitor performs traffic analysis, detects active machines in the network, maintains a network database with information regarding network topology and machines, filters specific packets or protocols, and can also work as a traffic generator. The system has a user friendly interface simplifying the interaction with the network manager.<<ETX>>

SInBAD - A Digital Library to Aggregate Multimedia Documents

The University of Aveiro is currently developing SInBAD, an integrated system for digital libraries and archives. The aim of the project is to build an information system to support the aggregation of multimedia documents such as books, photographs, and audiovisual resources. All these resources are part of the academic life and identity of the University. The architecture adopted in SInBAD is divided into 3 subsystems - Library, Archive and Jazz - and is Web Service oriented. Also, documents are distributed by several Agents in a dynamic manner. The basic description model used in the documents is the element set defined by the Dublin Core Metadata Initiative, although each subsystem may use specific data structures according to the document type and format. In this paper we present the created system, pointing out the interoperability and the web service oriented architecture. Also, despite its distributed nature, users may search simultaneously in all documents.

A management architecture based on network topology information

This paper describes the development of a formalism to represent Network Topology Information that provides hierarchical views of the network elements distribution, usable with advantage by management applications. It reviews some topology discovery tools and emphasizes the lack of a common methodology to represent the network cabling and organize the agent distribution information. The formalism, consisting on a descriptive language and on an object-oriented topology base, is described and some application areas, where this information can be used, are pointed. Finally it presents a Management API, as part of the overall architecture, that helps to show the usability of the Topology Information Base.

An Integrated Courseware Editor Based on OLE Technology

We described an integrated courseware editor based on OLE technology. Our courseware editor integrates existing applications like, drawing programs, spreadsheets, sound recorders and text processors into one consistent hypermedia environment. Based on a metaphor of an “electronic” overhead projector both authoring and reading of hypermedia documents are combined in one modeless editor. Our current prototype will be demonstrated at the poster session.

aRDF: a plugin to expose RDFa semantic information using Grails

For application developers data is the most important resource that can be found in the web, yet access to it is often subjected to barriers that hinder data reuse and interoperability. The semantic web brings with it the promise of a web of data (instead of the current web of documents) that will help to lower some of the barriers developers encounter when trying to gather data from multiple sources. Instead of having to resort to brittle screen-scrapping techniques, if data that is already present in web pages is encased in markup (such as RDFa) that makes it meaning explicit, developers can harvest that data directly and without ambiguities, turning human readable into machine readable data without the need to duplicate data. Since most of todays web development is done using web application frameworks that generate pages dynamically, placing that kind of markup unassisted is not feasible. As such there is the need for tools that extend the functionalities provided by web application frameworks in order to be able to add that kind of markup to a dynamically generated page, using the correct information for each item. In this paper we introduce one of those tools, aRDF, a plugin for the Grails web application framework that can be used to generate RDFa enhanced pages based on annotated underlying domain information.

Web annotation system based on Web services

Annotation tools allow users to complement existing documents with comments, suggestions or other information. Currently, desktop annotation tools are much more sophisticated than those available for annotating Web documents. EspiritUs is a Web services based system designed to allow users to create, share, and search annotations on the Web. In this article we analyze in detail existing Web annotation tools, present the adopted architecture based on XML technologies, describe the system implementation and present two possible annotation scenarios. Finally, we present some conclusions and guidelines for future work for this project.

Hypermedia authoring tools based on OLE technology

This paper report on recent and on going work related to the design of a set of hypermedia authoring tools intended to produce courseware, to be used for self learning or distance learning and training environments in a cooperative way. These tools have roots in a standalone hypermedia editor developed to create courseware, to which were added other tools to enhance its usability, namely a hypermedia player to view courseware in self study mode, and a hypermedia browser to create, to navigate and to display graphically the hypermedia document structure. The underlying metaphors are the overhead projector, the transparency and the layer. This system was developed for the MS-Windows environment, supporting OLE technology. We discuss the impact that such technology might have on the “look and feel” of hypermedia learning material and we describe the implementation of a Hypermedia Editor, Browser and Player tools.Part of this work is carried out in the context of the Co-Learn European project, which is aiming to design and to implement a third generation cooperative learning environment.

User Profiles in Corporate Scenarios

In an organizational/corporative environment, each user can perform different roles throughout the time. Dynamic user profiles can be used to accomplish this variation specification. A user profile is a set of information about a given user in a given context and on a specific period of time. The concept of dynamic profiling simply means that the relevant information about the user can vary in time. User profiling is usually related to web advertisement of goods and services for a user in a Web site, by means of gathering information of the users interests and then harvesting the web over these interests. The profile discussed in this paper is service related, directly depending from the users condition in an organization.

Contact@UA - A Profile Driven Portal

Contact@UA is an underway project in development at University of Aveiro, Portugal. The goal of the project is to provide an online web portal that can be used as a front-end for all University users - students, teachers, staff- and services library, administration, elearning, email. The aim of Contact@UA is not to build a bulk of new services, but instead to integrate the existing ones, in a dynamic web interface that self reconfigures according to the preferences and privileges of the user that logs into the portal. One of the key features of this portal is the usage of a web service (WS) architecture system to integrate the information collected in the existing services.