[05_MSc_magalhaes]
Luiz Gustavo Bustamante MAGALHÃES. Multi-resolução de geometria de terrenos armazenados em memória secundária. [Title in English: Multi-resolution of out-of-core terrain geometry]  M.Sc. Diss. Port. Presentation: 13/12/05 62 p. Advisor: Waldemar Celes Filho.

Abstract: The visualization of large terrains is a challenging Computer Graphics issue. The number of polygons required to faithfully represent a terrain's geometry can be too high for real-time visualization. To solve this problem, a multi-resolution algorithm is used to feed the graphics processor only with the most important polygons, without visual quality loss. The amount of data is another important problem, as it can easily exceed a computer's RAM. Thus, a system to manage out-of-core data is also required. The present work proposes a simple and scalable solution to visualize the geometry of large terrains based on three key points: a data structure to represent the terrain in multi-resolution, an efficient visualization system and a data paging and prediction system. Similarly to other works, the system uses a quadtree data structure due to its simplicity, along with the efficiency and the low memory use of an array-based implementation. Each node of the quadtree represents a tile of the terrain. The implementation is divided in two threads, one to manage the tiles and the other for visualization. The tile-management thread is responsible for loading/unloading tiles into/from the memory. This thread uses a camera-movement prediction mechanism to load tiles that can be used in the near future and remove tiles that probably will not be necessary. The visualization thread is responsible for viewing the terrain, computing the projected error, eliminating tiles that are not visible and balancing the quadtree structure in order to eliminate cracks or T-vertices on the terrain's surface. The visualization can be made by means of a fidelity-based or a budget-approach.

[05_MSc_loaizafernandez]
Manuel Eduardo LOAIZA FERNANDEZ. Implementação de um dispositivo de rastreamento óptico com 6 graus de liberdade para interação com aplicações de realidade virtual. [Title in English: Implementation of an optical tracking device with 6 degrees of freedom for interacting with virtual reality applications]  M.Sc. Diss. Port. Presentation: 01/04/05  105 p. Advisor: Marcelo Gattass and Alberto Barbosa Raposo.

Abstract: Tracking systems are a fundamental technology in virtual reality systems. They provide a continuous detection of the position and orientation of markers or specific objects that the user employs to interact with the system. One of the technologies most commonly used to implement these types of systems is the optical tracking, which allows the users to have more freedom in their movements because it does not need cables or mechanical elements that can restrict or hinder the immersion sensation that is tried to create in the interaction with virtual reality environments. This work presents the construction and implementation of an input device that is based on optical tracking that is used for interaction with semiimmersive virtual reality applications on ordinary desktop environments. This device has the capability to get the six degrees of freedom of the movements made by a set of markers that are controlled by the user hand. Based on the six degrees of freedom recovered, the device is complemented with the ability to emit events that allow the interaction of the user with the application. Finally, an application is presented for demonstrating the use of the generated events and the performance of our device.


[05_PhD_leal]
Marcus Amorim LEAL. Finalizadores e referências fracas: interagindo com o coletor de lixo. [Title in English:  Finalizers and weak references: interacting with the garbage collector] Ph.D. Thesis. Port. Presentation: 15/09/05 140 p. Advisor: Roberto Ierusalimschy.

Abstract: Most mainstream programming languages support finalizers and weak references. In spite of that, these abstractions are still modestly known by programmers in general. Even among language designers there seems to be no common view on how to define their semantics, and language implementations certainly reflect that. In this thesis we explore the concepts of finalizer and weak reference by discussing several important issues that, as far as we know, have not been explored by other authors. After presenting a survey on how finalizers and weak references are supported by actual programming languages, we thoroughly examine their semantics and discuss alternative implementation strategies. We also use an operational approach to develop a formal model for reasoning about garbage collection and its interaction with client programs. By explicitly representing low-level details, such as heap memory and its addresses, we were able to clearly specify memory management actions, and prove several important memory-related language invariants. Using this model we describe a formal semantics for finalizers and weak references, exploring some of its many subtleties. We believe that the topics covered here can serve as a relevant reference for further investigations, and also help to guide actual implementations.

[05_MSc_glasberg]
Mark Stroetzel GLASBERG. ActivePresentation: Um Sistema para apresentações distribuídas em ambientes de computação ubíqua. [Title in English: ActivePresentation: a system for distributed multimedia presentations in ubiquitous computing environments]  M.Sc. Diss. Port. Presentation: 09/11/05     p. Advisor: Renato Fontoura de Gusmão Cerqueira.

Abstract: The diminishing costs and the diversity of computational devices are creating increasingly complex and sophisticated computational environments. Nonetheless, such environments still lack integration software to simplify their use and to better explore their potential. In response to this issue, ubiquitous computing systems are being developed to create remote control mechanisms of applications and devices. At the same time, research groups in the area of multimedia deal with other issues, such as synchronization between devices, resource management and document standard definitions. The purpose of this work is to join the e orts of both areas in order to build presentations using the ubiquitous computing paradigm. In this work, we introduce the ActivePresentation infrastructure, based and developed through the study of di erent prototypes. In addition, we propose a multimedia document format called NCLua to orchestrate such presentations.

[05_MSc_quintanatruyenque]
Michel Alain QUINTANA TRUYENQUE. Uma aplicação da visão computacional que utiliza gestos da mão para interagir com o computador. [Title in English: A computer vision application for hand-gestures human computer interaction] M.Sc. Diss. Port. Presentation: 28/03/05  100 p. Advisor: Marcelo Gattass.

Abstract: Computer Vision can be used to capture gestures and create more intuitive and faster devices to interact with computers. Current commercial gesture-based interaction devices make use of expensive equipment (tracking devices, gloves, special cameras, etc.) and special environments that make the dissemination of such devices to the general public difficult. This work presents a study on the feasibility of using Web cameras as interaction devices based on hand-gestures. In our study, we consider that the hand is clean, that is, it has no (mechanical, magnetic or optical) device. We also consider that the environment where the interaction takes place has the characteristics of a normal working place, that is, without special lights or backgrounds. In order to evaluate the feasibility of such interaction mechanism, we have developed some prototypes of interaction devices. In these prototypes, hand gestures and the position of fingers were used to simulate some mouse and keyboard functions, such as selecting states and objects, and defining directions and positions. Based on these prototypes, we present some conclusions and suggestions for future works.

[05_PhD_assis]
Patrícia Seefelder de ASSIS. Arquitetura para adaptação e meta-adaptação de sistemas hipermídia. [Title in English: An Architecture for adaptation and meta-adaptation in hypermedia systems]  Ph.D. Thesis. Port. Presentation: 12/08/05 130 p. Advisor: Daniel Schwabe

Abstract: This dissertation defines an architecture for adaptation and meta-adaptation in hypermedia systems, using models proposed for the Semantic Web. Adaptative application are able to alter some of their characteristics, such as its navigation model or presentation model, according to the adaptation context. This context may include information about the user, such as her preferences, navigation history, etc., and about the execution environment, such as access device, bandwidth, etc. Meta-adaptive applications are able to alter both its models and its adaptation process according to the adaptation context. The proposal extends the SHDM model with a context model, adaptation rules and execution  architecture. It is shown, by comparison, that the major adaptation models described in the literature can be seen as particular cases of the proposed model and architecture.
 

[05_MSc_bastosjunior]
Paulo Roberto de Oliveira BASTOS JUNIOR. Elicitação de requisitos de software através da utilização de questionários. [Title in English: Software requirements elicitation through the use of questionnaires] M.Sc. Diss. Port. Presentation: 26/04/05 88 p. Advisor: Julio Cesar Sampaio do Prado Leite.

Abstract: Questionnaire is one of the techniques available for requirements elicitation. A questionnaire is a document used to guide one or more people to answer one or more questions. The elaboration of a questionnaire is a process more complex than it can make look like. A questionnaire that is not well formulated can lead to unreliable information and may be harmful to the project in question. Although there is no standard method for the construction of questionnaires, there are recommendations from diverse authors with regard to this important task in the process of eliciting information. The work presented here details a technique for identifying the necessary and common stages for the creation of a questionnaire. A method for the construction of questions is proposed, which uses as base a list of requirements for the construction of quality questionnaires, obtained from the literature in the areas of social sciences and marketing. A tool for the elicitation of software requirements, by means of
questionnaires is presented.

[05_MSc_mello]
Reinaldo Xavier de MELLO. Um modelo de escalonamento colaborativo de eventos baseado em corrotinas. [Title in English: A collaborative model for event scheduling using coroutines]  M.Sc. Diss. Port. Presentation: 14/09/05 64 p. Advisor: Renato Fontoura de Gusmão Cerqueira

Abstract: Event oriented systems are becoming present on many domains of applications. Distributed systems and graphical interactive systems are classical examples of environments that adapt well to the concept of event oriented programming. There are also emerging scenarios like cellphone runtime environments.  Despite the growing presence on the computational systems, some challenges still remain, like efficient method dispatch models and the management of concurrent processing of the event handlers. This work propose a model for an event scheduler using collaborative routines. We introduce a study on some mainstream scheduler models and propose a model where the scheduler holds the responsibility to encapsulate the complexity of managing multiple lines of execution, minimizing the CPU time wasted with blocking methods.  The coroutine model allows the management of these multiple lines of execution using a general control abstraction, which allows seamless context switching during the multiple suspending and
resuming of the routine. Also, without preemption, there is no overhead due to access control of the shared resources. The proposed model is tested on two different scenarios: one programming framework designed to be run on mobile phones, a fully asynchronous environment with low processing power and severe memory constraints; and a CORBA middleware written in LUA, where the communication between distributed objects is based on the remote procedure call model.
 

[05_MSc_carvalho]
Richard Werneck de CARVALHO. Um ambiente de suporte para uma linguagem de modelagem de sistemas multi-agentes. [Title in English: An environment of support for a modeling language of multi-agents systems] M.Sc. Diss. Port. Presentation: 11/03/05   155 p. Advisor: Carlos José Pereira de Lucena.

Abstract: This work considers the creation of an environment that gives computational support to the development of multi-agents systems, assisting the developer during the cycle of life of construction (the modeling to the implementation) of these systems. We will be using ANote as modeling language for specification and analysis of multi-agents systems and the architecture ASYNC for the development process. Thus occurring, a transformation of the diagrams of ANote for architecture ASYNC.


[05_MSc_paes]
Rodrigo de Barros PAES. Regulando a interação de agentes em sistemas abertos - uma abordagem de leis. [Title in English: Regulating agent's interaction - a law enforcement approach] M.Sc. Diss. Port. Presentation: 18/03/05  119 p. Advisor: Carlos José Pereira de Lucena and Paulo Sérgio Conceição Alencar.

Abstract: In this work, we propose an approach for regulating agents’ interaction on an open multi-agent system. In open systems, agents are immersed in a highly unpredictable environment, they can be self-interested, and other agents are frequently unknown beforehand. We argue that, in some applications, unexpected behavior may lead to system faults. For this reason, we propose a law enforcement approach to build open multi-agent systems where a certain degree of control over agents’ behavior is desirable. A conceptual model is proposed to specify how the interactions of an open multi-agent system should happen. This model deals with concepts such as norms, constraints and scenes in a integrated way. We also propose a declarative language that allows the interaction’s specification according to the elements that compose the conceptual model, and a software infrastructure that acts as a mediator monitoring and enforcing agents’ interaction.


[05_MSc_hermann]
Rodrigo de Proença Gomes HERMANN. Controle automático de câmera em ambientes virtuais dinâmicos. [Title in English: Automatic camera control in virtual dynamic environments] M.Sc. Diss. Port. Presentation: 13/09/05 54 p. Advisor: Waldemar Celes Filho.

Abstract: With the evolution in graphics processing power and the popularization of electronic games, new forms of entertainment, such as being a game spectator. The requirements for positioning the camera for the spectators to view the games are different from those applied to players. The camera for the players must fulfill playability requirements, while the camera for the spectators must explore different viewing angles in order to increase the immersion in the game environment and to explore the thrill of the scenes. The cinema has evolved a whole cinematographic language that optimizes the scene interpretation. Recent research has been seeking to apply cinematography to game visualization. The main challenge in the adaptation of the cinematographic language for games lies in the existence of a dynamic environment in which the story's progress cannot be anticipated. Three modules can be identified to adopt the cinematographic language in games: screenwriter, responsible for identifying what is happening  in the scene; director/editor, responsible for defining the best takes to capture the scene; and cinematographer, responsible for positioning the camera in the dynamic environment to better comply with the director/editor's demands. The present work proposes the implementation of a cinematographer module. Based on camera position requirements obtained from an external module, we propose a camera model that automatically positions the camera. The positioning requirements are expressed by a set of constraints that must be respected by the camera model. The camera uses a physical model based on a particle system oriented by Verlet's method, and employs the relaxation method to obtain the system's convergence in order to comply with imposed constraints. Computational experiments have demonstrated the capacity of the proposed module to comply with sophisticated camera positioning rules based on compositions of simple constraints. Cinematography principles such as framing , camera position and movement, and respecting the line of action are easily accomplished by the  proposed module.

[05_MSc_espinha]
Rodrigo de Souza Lima ESPINHA. Visualização volumétrica interativa de malhas não-estruturadas utilizando placas gráficas programáveis. [Title in English: Interactive volume visualization of unstructured meshes using programmable graphics cards] M.Sc.Diss. Port. Presentation: 18/03/05  86 p. Advisor: Waldemar Celes Filho.

Abstract: Volume visualization is an important technique for the exploration of threedimensional complex data sets, such as the results of numerical analysis using the finite elements method. The efficient application of this technique to unstructured meshes has been an important area of research in the past few years. There are two basic methods to visualize volumetric data: surface extraction and direct volume rendering. In the first, the iso-surfaces of the scalar field are explicitly extracted. In the second, which is the one used in this work, scalar data are classified by a transfer function, which maps the scalar values to color and opacity, to be visualized. With the evolution of personal computer graphics cards (GPU), new techniques for volume visualization have been developed. The new algorithms take advantage of modern programmable graphics cards, whose processing power increases at a faster rate than the one observed in conventional processors (CPU). This work evaluates and compares two GPU- based algorithms for volume visualization of unstructured meshes: view- independent cell projection (VICP) and ray-tracing. In addition, two adaptations of the studied algorithms are proposed. For the cell projection algorithm, we propose a GPU data structure in order to eliminate the high costs of the CPU to GPU data transfer. For the raytracing algorithm, we propose to integrate the transfer function in the GPU, which increases the quality of the generated image and allows to interactively change the transfer function.


[05_MSc_machado]
Rodrigo Prestes MACHADO. Um serviço de matchmaking de interesses dependentes de localização. [Title in English: A service for matchmaking of location-dependent interests] M.Sc. Diss. Port. Presentation: 19/05/05  93 p. Advisors: Carlos José Pereira de Lucena and Markus Endler.

Abstract: This work presents a matchmaking service (MMS) to enable meetings among co-localized people sharing similar interests. To make possible meetings and collaborations, the MMS analyses profiles of co-localized users using mobile devices, and indicates which users have a high degree of similarity among their profiles. The profiles are described using ontologies in OWL format (web ontology language), where the subjects of interest may be related with symbolic regions. The information about localization is obtained through interactions of MMS with a location service (Location Inference Service - LIS) present in MoCA architecture (Mobile Collaboration Architecture). The MMS service is built in a client/ Server architecture. The MMS provides the matchmaking service in two modes: synchronous and asynchronous. The synchronous mode allows users to request MMS to find people with similar interest in the same location. The asynchronous mode allows users to subscribe to the MMS service to receive automatic notifications when the MMS finds people in the neighborhood with similar interests. The MMS client provides access to the service and allows edition of users' profiles of interest for each localization.

[05_MSc_costa]
Romualdo Monteiro de Resende COSTA. Integração e interoperabilidade de documentos MPEG-4 e NCL. [Title in English: Integration and interoperability of MPEG-4 and NCL documents] M.Sc. Diss. Port. Presentation: 06/04/05  180 p. Advisor: Luiz Fernando Gomes Soares.

Abstract: The MPEG-4 standard object-oriented approach, employed to the encoding of audiovisual content, is similar to those used on many models and languages for multimedia/hypermedia document specification. Among those languages, the NCL (Nested Context Language), used in the HyperProp system, introduces a series of new concepts that can be integrated to the standard, with advantages.  Initially, the proposal of this work is to convert NCL to MPEG-4 (XMT-O) documents and vice versa, allowing authoring and formatting tools to be used in the specification and presentation of documents in both languages. This work also proposes both the placing of MPEG-4 scenes as media objects and NCL language compositions, allowing the establishment of relationships among scenes. In order to allow displaying these new NCL objects, an MPEG-4 player is incorporated to the HyperProp Formatter. The MPEG-4 player is able to report to the controller the occurrence of events that, among other things, allows the synchronization between MPEG-4 scenes and othe r NCL objects, including other MPEG-4 scenes.  Finally, exploring the concept of templates, introduced by the NCL language, the authoring in the MPEG-4 is improved, by means of the definition of new semantics for XMT-O language compositions and the design of compilers for this language.


[05_PhD_siqueira]
Sean Wolfgand Matsui SIQUEIRA. EDUCO - modelando conteúdo educacional. [Title in English: EDUCO: modelling educational content] Ph.D Thesis. Port. Presentation: 14/03/05  138 p. Advisor: Rubens Nascimento Melo and Maria Helena Lima Baptista Braz.

Abstract: In e-learning, the development of multimedia educational content material has been a success factor. However, as these processes are expensive and timeconsuming, there is a need for making the content reuse easier and institutions are establishing partnerships in order to share content and services. In this context, Learning Objects (LO) and standard metadata have been grown in acceptance. In spite of this, several developers have found it difficult to use and reuse LOs. Then there is still a need for providing mechanisms that promote LO reuse. The current trend is on making these LO even smaller, structured according to a hierarchy of interconnected nodes. Some recent approaches are based on the use of topic maps, ontology and knowledge bases in order to work with the content that are embedded into the educational material. This thesis presents a model for structuring and representing this content according to the involved information and conceptual unities. In addition, we also present an architecture that allows the different semantic levels of information to be considered in an e-learning environment. This architecture is based on related work on data integration and it establishes a context for the proposed modeling approach for representing educational content and therefore contributes for its acceptance and use by the e-learning community.

[05_PhD_urrutia]
Sebastian Alberto URRUTIA. Otimização em esportes: programação de tabelas e problemas de classificação. [Title in English: Optimization in sports: timetabling and qualification problems]  Ph.D. Thesis. Port. Presentation: 20/10/05  93 p. Advisor: Celso da Cruz Carneiro Ribeiro.

Abstract: Sports management is a very attractive and not very explored area for applications of Operations Research. Problems in this area use to have simple formulations and reach a big coverage by the media. Although their formulations are simple, in general these problems are difficult to be solved in computational terms. The results of many academic works in this area have been accepted as solutions for real problems and some solutions are being implemented. This thesis has the main objective of studying two types of problems that appear in the sports area: the fixture creation and the qualification problems. Fixture creation (also known as sport scheduling) for sport competitions is a difficult task, in which several combinatorial optimization techniques has been applied. In this thesis, the Mirrored Traveling Tournament Problem is formulated as a graph optimization problem. The problem is solved using approximation algorithms. Two heuristics are introduced for this problem. The first one is very fast and is used to supply initial solutions for the second one which is able to obtain high quality solutions in reasonable computation times. Dual limits are deduced for a particular type of instances. These limits allow to prove the optimality of the heuristically obtained solutions for instances that are much bigger than those solved in the literature. Finally, an integer programming model is introduced in which valid inequalities are added. The qualification problems aim to obtain necessary and sufficient conditions for the playoffs qualification of a given team in terms of the number of points to be obtained.  Integer programming models are introduced which allow solving these problems in the context of the Brazilian Football Championship.
 

[05_MSc_cavendish]
Sérgio Alves CAVENDISH. Algoritmos de ajuste elástico para vídeo em fluxos MPEG-2. [Title in English: Elastic time algorithms for video in MPEG-2 Flows]  M.Sc. Diss. Port. Presentation: 08/11/05     p. Advisor: Luiz Fernando Gomes Soares.

Abstract: In hypermedia presentations, one of the main tasks provided by the orchestrator is the synchronization of all presentation objects, which may be achieved by elastic time adjustment of period of exhibition of the objects, or simply timescale adaptation. This technique can be applied at compilation time, in order to keep track of synchronism relationships specified by authors, or at presentation time, to prevent any temporal mismatch caused by transmission or execution environments. This work presents a set of mechanisms to carry out timescale adaptation in MPEG-2 Systems and Video streams, proposing algorithms to perform compression and expansion of exhibition period, also called playback dilation, rate control, inter-media synchronization and clock reconstruction. In order to be performed at execution time, timescale operations are realized directly in compressed MPEG-2 streams, requiring no transcodification.

[05_MSc_badiola]
Sérgio Mateo BADIOLA. Integração de suporte para geração de carga dinâmica ao ambiente de desenvolvimento SAMBA. [Title in English: Support integration of dynamic workload generation to SAMBA framework] M.Sc. Diss. Port. Presentation: 04/02/05 93 p. Advisor: Noemi de La Rocque Rodriguez.

Abstract: Alexandre Plastino's thesis presents a framework for the development of SPMD parallel applications, named SAMBA, that enables the generation of different versions of a parallel application by incorporating different load balancing algorithms from an internal library. This dissertation presents a dynamic workload generation's tool, integrated to SAMBA, that affords to create, at execution time, different external workload profiles to be applied over a parallel application in study. The objective is to enable that a parallel application developer selects the most appropriated load balancing algorithm based in its performance under variable conditions of external workload. In order to validate this integration, two SPMD applications were implemented.

[05_MSc_moura]
Simone Leal de MOURA. Uma arquitetura para integração de repositórios de objetos de aprendizagem baseada em mediadores e servicos Web. [Title in English: An architecture based on mediators and Web services for integrating learning object repositories]  M.Sc. Diss. Port. Presentation: 19/08/05 157 p. Advisors: Rubens Nascimento Melo and Sean Wolfgand Matsui Siqueira.

Abstract: In web-based education there is an emphasis on reusing and sharing instructional content due to the complexity of the development process of high-quality learning materials. It leads to the learning  objects orientation as well as to partherships among institutions to promote sharing of these objects. In order to contribute to these efforts, we propose an architecture based on the mediators and wrappers for integrating learning objects repositories. The components of this architecture were implemented by the use of web-services and the integration processes were enriched by ontologies.  The use of mediators allows a query to be redefined as sub-queries that are distributed to the data sources and the results to be integrated. The wrappers allow the data sources to understand the sub-queries and the mediator to understand the respective answers. The implementation of the architecture components as web services allows more flexibility and interoperability among the participants of the community. The formalism of ontologies is used to deal with the semantic heterogeneity as the metadata concepts of each repository are described and the equivalences are established. The development of this architecture is called LORIS, an integration system of learning objects' repositoires.  LORIS is beings adopted by PGL, an international parthership project for promoting web-based education.

[05_PhD_vieira]
Tatiana Almeida Souza Coelho VIEIRA. Execução flexível de workflows. [Title in English: Flexible workflow execution]  Ph.D. Thesis. Port. Presentation: 11/08/05 429 p. Advisor: Marco Antonio Casanova.

Abstract: Workflow management systems usually interpret a workflow definition rigidly, allowing no derivations during execution. However, there are real life situations where users should be allowed to deviate from the prescribed static workflow definition for various reasons, including lack of information about parameter values and unavailability of the required resources. To flexiblilize workflow execution, this thesis proposes an exception handling mechanism that allows the execution to proceed when otherwise it would have been stopped. The proposal is introduced as a set of extensions to OWL-S, the language adopted to define workflows, and is based on process and resource ontologies that capture the semantic information needed for the flexibilization mechanism. The thesis also defines an operational semantics for a fragment of OWL-S and the proposed extensions, as well as a distributed architecture for a workflow management system. In particular, the semantics define a form of transactional behavior for the execution of a workflow instance, in the sense that it guarantees that either all actions executed by the instance terminate correctly or they are all abandoned.

[05_MSc_mello]
Télvio Martins de MELLO. Uma biblioteca para criação de máquinas virtuais baseadas em processadores de rede. [Title in English: A library for the creation of network-processors-based virtual machines] M.Sc. Diss. Port. Presentation: 28/03/05  104 p. Advisor: Sérgio Colcher.

Abstract: The aim of this work is to study, propose and implement a tool that allows the experimentation with architectures that follow the Network Processors (NP) paradigm. A generic object library was implemented, allowing the emulation of the various hardware components, such as memories, registers, arithmetic-and-logical units, control units etc., that are commonly used within specific architectures for protocol processing. The integrated usage of these components will provide an environment where virtual machines can be created and tested to verify the behavior of many different operations. Besides the library itself, three use cases are presented to validate and show the utility of the tool: the first is an implementation of a processor created just for the sake of testing and the other two are implementations of architectures based on the MCS85 processor and on the ARM kernel of the Intel IXP Network Processor.