Mário Meireles Teixeira

Using adaptive priority scheduling for service differentiation QoS-aware Web servers

The current best-effort service model used on the Internet treats all requests uniformly, both in the network and at the application level. However, sometimes it is desirable to provide different classes or levels of service in order to satisfy the needs of different users and applications. In this paper, we propose an architecture for the provision of differentiated services at the Web server level. The architecture is verified by means of a simulation model and real Web server traces are used as workload. Two priority-based algorithms are implemented in the architecture aiming at service differentiation. The adaptive algorithm, an innovative solution at the application domain, allows the tuning of the priority level provided and determines how strict the use of priorities would be. The system can then adapt itself to various workloads, an essential feature in a highly dynamic environment such as the Web.

Textual authoring of interactive digital TV applications

Authoring tools for hypermedia languages usually provide visual abstractions, which hide the source code from the author aiming to simplify and accelerate the development process. Among other drawbacks, these abstractions modify or even break the communication process between the author and the language designer, since these languages were designed to be readable and understandable by its target audience. This paper presents a textual approach to hypermedia authoring that does not have these inconveniences, but rather uses typographical accessories, such as program visualization, hypertextual navigation, and semi-automatic error correction. The proposed approach exploits concepts known to the author and does not imply in extra cognitive overload. A use case is presented, namely the NCL Eclipse authoring environment, for Nested Context Language, the Brazilian Digital TV and ITU-T standard.

Negotiation mechanisms on application level: a new approach to improve quality of service in Web servers

This paper describes a negotiation mechanism inserted in a Web server model with differentiated services. All the results of this article have been obtained by means of simulation using for this a queueing network model representing a Web server with QoS. The results also confirm that this new approach enhances the quality of service provided to clients, mainly in overload situations, being an aid in the process of request admission and dropping

Management and Integration of Information in Intrusion Detection System: Data Integration System for IDS Based Multi-Agent Systems

In this paper, we present a model, an architecture and an implementation of an information manager for an IDS (intrusion detection systems), using the technology of multi-agent systems and Web services. This manager has been integrated to NIDIA (network intrusion detection system based on intelligent agents), which is an IDS whose architecture consists of a group of cooperative agents. In our proposal, the NIDIA is adapted and extended so that its services uses updated and secure information. The goal of the information manager module is to keep safe and update of information that is necessary for the development of inherent functions of an IDS

An approach for textual authoring of hypermedia documents based on the use of programmatic visualization and hypertextual navigation

Authoring tools for hypermedia languages often provide visual abstractions that hide the source code from the author with the objective of simplifying and accelerating the development process. Among other drawbacks, these abstractions modify or even prevent the communication process between the author and the designer of the language, which has been designed to be streamlined and readable by its target audience. This paper presents a textual approach to hypermedia authoring that does not inherit these inconveniences, but also makes use of typographical accessories such as programmatic views and hypertextual navigation. By setting an environment for hypermedia authoring similar to the presentation engine of the source language, the proposed approach uses concepts known by the author and does not imply in cognitive overload. A case of use is exemplified by the NCL Eclipse authoring environment, toward for Nested Context Language, the standard for the Brazilian Digital TV System.

Eventline: representation of the temporal behavior of multimedia applications

This paper presents the concept of eventline as a visual representation proposal for the temporal behavior of multimedia applications. The main difference of this proposal when compared to the timeline paradigm is the replacement of the temporal continuous axis to a temporal discrete axis based on the occurrence of events. Media synchronization in each eventline is based on the relative time of a main media. User interaction is expressed as the navigation between multiple eventlines. The objective of this work is to provide a simplified alternative for authoring of interactive multimedia applications.

A progressive transmission scheme for vector maps in low-bandwidth environments based on device rendering

The Internet has created an interesting environment for geospatial data sharing, so that users may transfer, visualize, manipulate and interact the data sets. This environment not only provides new opportunities to geospatial data usage, but also introduces new problems that should be addressed in order to provide an efficient and effective use of these datasets. One of such problems is related to the use of these spatial datasets in a low-bandwidth environment, such as those involving mobile computing. This paper presents a progressive transmission method for vector maps on the Web. The proposed method anticipates the map rasterization process to be performed at the server side, so that the amount of information transmitted may be reduced. We combine scale-dependent transmission techniques with simplification and progressive ones, in order to maximize the overall performance of a Web GIS environment.

Migrating Legacy Web Apps to Cloud Computing Environments: An architectural and economic perspective

In this talk, we discuss some challenges found when porting traditional web applications to a cloud computing environment. We take the AWS cloud platform as a reference and describe a proposal for a Web hosting solution using AWS products.

Incremental validation of digital TV applications in nested context language

This paper presents an incremental validation process for multimedia documents describing interactive digital TV (iTV) applications. This work delves more specifically into documents defined in Nested Context Language (NCL), a declarative language standard adopted by ISDB-Tb and ITU-T for IPTV. The focus of incremental validation, the approach proposed in this work, relies on checking only the pieces of code that have been modified since the latest validation as well as those parts that have suffered any side effects, thus eliminating the need for a thorough checking of the document. The implications of performing this type of validation in a declarative language such as NCL are discussed and implementation details are given. Performance tests comparing the standard and incremental validation approaches have been carried out revealing a significant improvement concerning the latter.

Policies for Assisted Virtual Machine Selection in Cloud Computing Environments

In this paper we propose an end-to-end approach to the VM allocation problem using policies based uniquely on round-trip time measurements between VMs. We propose and implement end-to-end algorithms for VM selection that cover desirable profiles of communications between VMs in distributed applications in a cloud setting. The use of informed VM selection allowed us to select instances with an average RTT up to 85% lower, in one case, and to find local and global centers of VM clusters in another. The approach described is completely independent from cloud architecture and is adaptable to different types of applications and workloads, as well as lightweight and transparent for cloud providers.