The development of distributed, reactive and collaborative services is quite challenging. Rapidly composing services for collaborative learning activities require some development methods and tools. This thesis presents an extension of the City Guide application, a platform that supports situated collaborative services developed by Surya Bahudar Kathayat his PhD thesis: <i>On the Development of Situated Collaborative Services</i>. The application was developed using the engineering method SPACE and its development tool Arctis. In the extension made, two new services instant messaging and group chat have be composed and integrated into the application. The two services have been identified as basic support services that are required for a true collaborative learning experience. Using the architecture of the application, the instant messaging and group chat services were developed as components that could be incorporated with other components within the application. The results show the instant messaging and group chat service as standalone functionalities that handle their own message routing within the application and hence did not require the use of any other messaging protocols. The results also show that by using this architecture with the necessary Arctis modifications, the City Guide application opens up for unexplored possibilities where new services can be rapidly developed and integrated.

Access control of NUTS uplinkWe will focus in the authentication and integrity part in this thesis.

Vehicular ad-hoc networks (VANETs) have envisioned various applications that substantially improve traffic safety and efficiency along the roads and highways. There are on-going projects both in academia and industry to standardize VANETs and to start off their real-life deployment. Despite the huge benefits envisioned by VANETs, they cannot be readily deployed as they are subjects of serious security and privacy concerns. These security and privacy concerns should be addressed and thus VANETs require a sound Identity management architecture before their anticipated deployment. Current research efforts on Identity management (IdM) in VANETs focus on employing Public Key Infrastructure (PKI) schemes to offer the well-known security and privacy requirements for VANETs. However, identity management is a far broader concept than offering security and privacy requirements.This thesis proposed a novel Identity management (IdM) architecture for VANETs that makes distinction between identity of the driver and the identity of the vehicle. To the best of our knowledge, our architecture is the first one to make such a distinction. Smartphones are used for establishing the identity of the driver while the IP Multimedia Subsystem (IMS) is used as an identity provider by establishing an OpenID provider within IMS. To preserve anonymity of users and to avoid location tracking, we tweaked OpenID so that it assigns different pseudonym OpenID identifiers for each user. Finally, we showed how our architecture can be used to realize interoperability across different VANET domains even in the absence of trust relationship among them.

In the last years hybrid optical networking is a topic of increasing interest for graceful migration to future high capacity integrated service networks.A new hybrid network architecture is proposed to harmonize different transport technologies and to support a suitable set of services: ''3-Level Integrated Hybrid Optical Network'' (3LIHON).The aim of this thesis is to study the performance of 3LIHON focusing on examining the Quality of Service (QoS) in the output part of the node.In particular we study the performance for Statistically Multiplexed (SM) traffic.In Chapter 1 we present the motivation of our study and the current work.We give the problem definition and define the goal of the thesis.Chapter 2 shows concepts and architecture of 3LIHON. Firstly we introduce the reference classes used and the Quality of Service (QoS) requirement.Furthermore we give a complete description of 3LIHON architecture describing transport services, architecture in detail, input and output part of the node.Finally we describe the advantages of 3LIHON network.To simulate the 3LIHON architecture we use a programming language called Simula and a context class for discrete event simulation called DEMOS.In Chapter 3 firstly we describe the simulation model implemented, moreover we give a code description.We show the sources characterization and the packets characterization for all type of traffic that 3LIHON is able to handle: Guaranteed Service Transport (GST) traffic, Statistically Multiplexed (SM) Real Time (RT) traffic and Statistically Multiplexed (SM) Best Effort (BE) traffic.The code used in this work is available in Appendix C.In Chapter 4 firstly we present the simulation scenario and then the obtained results.To evaluate the accuracy's level of our results we use a 95% confidence interval and more theoretical details about that are given in Appendix A.We consider three study cases and for each of them we analyze in details the Packet Loss Probability (PLP) of Statistically Multiplexed Real Time (SM/RT) packets, the Packet Loss Probability (PLP) of Statistically Multiplexed Best Effort (SM/BE) packets and the delay of Statistically Multiplexed Best Effort (SM/BE) packets in the Best Effort queue. Some additional results used to obtain the study case called Series Two in Chapter 2 are shown in Appendix B.In Chapter 5 are presented some conclusions of this work and in Chapter 6 we show some hints that can be the sparkle for further works.

Hybrid optical networks are considered as the most promising architectures for future optical networks, in order to achieve both better cost and performance. Dependability is a topic of increasing interest in order to provide the Quality of Service (QoS) expected for future optical networks. Recently, the 3-Level Integrated Hybrid Optical Network (3-LIHON) has been proposed as a new concept for future optical core networks, including different transport technologies to support a wide range of services. Due to the wide range of future telecommunication services foreseen for next generation optical backbone networks, the 3-LIHON architecture must be provided with differentiated dependability, in order to offer the availability demanded by the most critical services, as well as to utilize network resources efficiently. By focusing in a single 3-LIHON node, this thesis employs component redundancy to present a differentiated survivability model suitable for the 3-LIHON architecture. Several protection mechanisms for two of the three types of traffic supported by 3-LIHON are proposed in this research work. These mechanisms are analyzed by means of different dependability models, i.e. reliability block diagrams and Markov models; and a numerical evaluation of its unavailability is presented. In addition, simulation results measuring the impact on performance of some mechanisms are also presented. Then, the protection mechanisms are compared and evaluated, taking into account not only its unavailability and performance, but also other considerations such as cost and complexity. Finally, based on this evaluation, the best suited mechanisms are selected.

The Activity Coordination Tool (ACT) is a web application designed to automate theplanning and coordination of work packages. In the CMS experiment at CERN it isimportant that work packages in the underground facilities are properly planned inorder to not jeopardize time schedules, equipments, budgets and safety. The subjectof this thesis is the development of the database schema used by the ACT application.The schema has been developed from scratch in order to best fit the needs of CMS andto cover all aspects of the planning and coordination process not found in other CERNdatabases.Models and diagrams of the database schema are based on a step by step descriptionof the work package process. This step by step description was used to organize thedata, to make the data and data relationships consistency, and to make the databasestructure flexible for extensions in the future. These models would eventually be usedto implement the schema in the CMS online database.Another database at CERN has many similarities with the ACT database. These twodatabases will eventually merge due to common interest, and the ACT database schemaneeded therefore to resemble some tables in this database in order to facilitate themerging. Some problems with network traversal and security needs to be solved beforethese two databases can be merged.The architecture and usage of the database schema can affect the database performancebut it doesn’t contribute to the reliability of the databases system. The hardware andsoftware components making up the database system itself are usually the main contributorsto this. The CMS online network work hard to keep the performance and reliabilityof their database system as good as possible. Everything from disks to networkconnections is redundant. In addition to component redundancy are features providedby Oracle used to improve performance. The amount of server redundancy does howeverseem a bit exaggerated, and the performance could be slightly improved if otherOracle features were used.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / In this paper we analyze fundamental local-area communication issues related to proximity operations around near-earth asteroids. We are motivated by NASA's plan to send robotic spacecraft to numerous such asteroids in the coming years in preparation for an eventual manned mission. We consider here the case where multiple probes are deposited on the surface of an asteroid and must communicate the data they collect to each other and to earth by using the orbiting `mothership' as a relay. With respect to this scenario, we statistically analyze the ability of surface probes in various locations to communicate with the mothership as well as their abilities to network with one another. For the purposes of this analysis, we assume the simplest possible communications scenario: a surface probe can communicate with the mothership only when it has an unobstructed line of sight. At the frequencies of interest here, line of sight is a necessary condition but it is obviously not sufficient - the end-to-end link margins of our communications system must be high enough to support the desired/required data rates. The work presented in this paper extends our previous research in which we only analyzed the visibility of the locations on the surface of the asteroid. Here, we consider how visibility affects the required communications bandwidth and buffer sizes for both surface-to-spacecraft and surface-to-surface scenarios.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / In this paper we analyze fundamental local-area communication issues related to proximity operations around near-earth asteroids. We are motivated by NASA's plan to send robotic spacecraft to numerous such asteroids in the coming years in preparation for an eventual manned mission. We consider here the case where multiple probes are deposited on the surface of an asteroid and must communicate the data they collect to each other and to earth by using the orbiting `mothership' as a relay. With respect to this scenario, we statistically analyze the ability of surface probes in various locations to communicate with the mothership as well as their abilities to network with one another. For the purposes of this analysis, we assume the simplest possible communications scenario: a surface probe can communicate with the mothership only when it has an unobstructed line of sight. At the frequencies of interest here, line of sight is a necessary condition but it is obviously not sufficient - the end-to-end link margins of our communications system must be high enough to support the desired/required data rates. Nonetheless, this simplistic analysis represents the first step in characterizing the communication system requirement for the asteroid-local portion of the system.

No description available.

The automated functional and performance analysis of communication systems specified with some Formal Description Technique has long been the goal of telecommunication engineers. In the past SDL and Petri nets have been the most popular FDTs for the purpose. With the growth in popularity of UML the most obvious question to ask is whether one can translate one or more UML diagrams describing a system to a performance model. Until the advent of UML 2.0, that has been an impossible task since the semantics were not clear. Even though the UML semantics are still not clear for the purpose, with UML 2.0 now released and using ITU recommendation Z.109, we describe in this dissertation a methodology and tool called proSPEX (protocol Software Performance Engineering using XMI), for the design and performance analysis of communication protocols specified with UML. Our first consideration in the development of our methodology was to identify the roles of UML 2.0 diagrams in the performance modelling process. In addition, questions regarding the specification of non-functional duration contraints, or temporal aspects, were considered. We developed a semantic time model with which a lack of means of specifying communication delay and processing times in the language are addressed. Environmental characteristics such as channel bandwidth and buffer space can be specified and realistic assumptions are made regarding time and signal transfer. With proSPEX we aimed to integrate a commercial UML 2.0 model editing tool and a discrete-event simulation library. Such an approach has been advocated as being necessary in order to develop a closer integration of performance engineering with formal design and implementation methodologies. In order to realize the integration we firstly identified a suitable simulation library and then extended the library with features required to represent high-level SDL abstractions, such as extended finite state machines (EFSM) and signal addressing. In implementing proSPEX we filtered the XML output of our editor and used text templates for code generation. The filtering of the XML output and the need to extend our simulation library with EFSM abstractions was found to be significant implementation challenges. Lastly, in order to to illustrate the utility of proSPEX we conducted a performance analysis case-study in which the efficient short remote operations (ESRO) protocol is used in a wireless e-commerce scenario.