Compensation methods to support cooperative applications: A case study in automated verification of schema requirements for an advanced transaction model

Compensation plays an important role in advanced transaction models, cooperative work and workflow systems. A schema designer is typically required to supply for each transaction another transaction to semantically undo the effects of . Little attention has been paid to the verification of the desirable properties of such operations, however. This paper demonstrates the use of a higher-order logic theorem prover for verifying that compensating transactions return a database to its original state. It is shown how an OODB schema is translated to the language of the theorem prover so that proofs can be performed on the compensating transactions

Compensation methods to support generic graph editing: A case study in automated verification of schema requirements for an advanced transaction model

Compensation plays an important role in advanced transaction models, cooperative work, and workflow systems. However, compensation operations are often simply written as a^−1 in transaction model literature. This notation ignores any operation parameters, results, and side effects. A schema designer intending to use an advanced transaction model is expected (required) to write correct method code. However, in the days of cut-and-paste, this is much easier said than done. In this paper, we demonstrate the feasibility of using an off-the-shelf theorem prover (also called a proof assistant) to perform automated verification of compensation requirements for an OODB schema. We report on the results of a case study in verification for a particular advanced transaction model that supports cooperative applications. The case study is based on an OODB schema that provides generic graph editing functionality for the creation, insertion, and manipulation of nodes and links

An Agent Based Transaction Manager for Multidatabase Systems

A multidatabase system (MDBMS) is a facility that allows users to access data located in multiple autonomous database management systems (DBMSs) at different sites. To ensure global atomicity for multidatabase transactions, a reliable global atomic commitment protocol is a possible solution. In this protocol a centralized transaction manager (TM) receives global transactions, submits subtransactions to the appropriate sites via AGENTS. An AGENT is a component of MDBS that runs on each site; AGENTS after receiving subtransactions from the transaction manager perform the transaction and send the results back to TM. We have presented a unique proof-of-concept, a JAVA application for an Agent Based Transaction Manager that preserves global atomicity. It provides a user friendly interface through which reliable atomic commitment protocol for global transaction execution in multidatabase environment can be visualized. We demonstrated with three different test case scenarios how the protocol works. This is useful in further research in this area where atomicity of transactions can be verified for protocol correctness

Specifying Web Service Recovery Support with Conversations

International audienceWeb services offer a number of valuable features towards supporting the development of open distributed systems, built out of the composition of autonomous services. Nonetheless, the resulting systems must offer a number of non-functional properties and in particular dependabilityrelated ones, for acceptance by users, including effective exploitation in the e-business domain. However, dependability of composite services can only be achieved according to the recovery property of composedWeb services. This calls for the rigorous specification of the standard and exceptional behavior of Web services. This paper introduces the WS-RESC conversation language that addresses this issue. In a way similar to existing conversation languages, WS-RESC includes constructs for defining ordering and choices. However, WS-RESC further includes constructs for specifying concurrency since it is an inherent feature of distributed systems, and for specifying timing constraints and recovery properties of conversation since these are key behavioral properties in the context of dependability

System mechanisms for partial rollback of mobile agent execution

Mobile agent technology has been proposed for various fault-sensitive application areas, including electronic commerce, systems management and active messaging. Recently proposed protocols providing the exactly-once execution of mobile agents allow the usage of mobile agents in these application areas. Based on these protocols, a mechanism for the application-initiated partial rollback of the agent execution is presented in this paper. The rollback mechanism uses compensating operations to roll back the effects of the agent execution on the resources and uses a mixture of physical logging and compensating operations to rollback the state of the agent. The introduction of different types of compensating operations and the integration of an itinerary concept with the rollback mechanism allows performance improvements during the agent rollback as well as during the normal agent execution

Um Protótipo De Um Sistema De Software Para Geração De Formulários Para Coleta De Dados

TCC(graduação) - Universidade Federal de Santa Catarina. Campus Araranguá. Engenharia da Computação.A rápida evolução dos dispositivos moveis e com uma população brasileira de 82.7% que tem acesso à internet, estes dados permitiram que a coleta de dados para pesquisa de campo também pudesse se transformar. Os antigos formulários presentes nas coletas tradicionais podem ser transformados em páginas WEB, sendo assim os pesquisadores não são impedidos por custo, tempo ou distância. Alguns projetos desenvolvidos pelos profissionais da área da saúde da UFSC de Araranguá ainda utiliza o sistema de coleta de dados através do modelo tradicional, foi através desta necessidade, foi elaborado em conjunto com os pesquisadores da área da saúde um protótipo que pretende facilitar todo este processo de coleta de dados, passando pelas etapas de cadastro de paciente, criação de formulários, analise e extração de resultados. Este protótipo surge como uma ferramenta de auxílio aos pesquisadores realizar uma coleta de dados de modo remoto, por exemplo, sem gerar aglomeração e contato direto, de modo a evitar a propagação do vírus. Além de ajudar os pesquisadores otimizando no levantamento dos dados em campo.The rapid evolution of mobile devices and with a 82.7% Brazilian population that has access to the internet, these data allowed the collection of data for field research to also be transformed. The old forms present in traditional collections can be transformed into WEB pages, so researchers are not hindered by cost, time or distance. Some projects developed by health professionals at UFSC in Araranguá still use the data collection system using the traditional model, it was through this need, a prototype was developed together with the researchers that aims to facilitate this entire data collection process. , going through the steps of patient registration, creating forms, analyzing and extracting results. This prototype appears as a tool to help researchers conduct data collection remotely, for example, without generating agglomeration and direct contact, in order to prevent the spread of the virus. In addition to helping researchers optimizing data collection in the field

Access control model for WebServices eGovernment infrastructure.

Tam Ka Wing Matthew.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.Includes bibliographical references (leaves 84-89).Abstracts in English and Chinese.Acknowledgement --- p.iAbstract --- p.iTable of Contents --- p.iiiChapter 1 --- Introduction --- p.1Chapter 2 --- eGovernment Requirements --- p.5Chapter 2.1 --- Efficient Operation --- p.5Chapter 2.2 --- Citizen-centric Government --- p.7Chapter 2.3 --- Security --- p.10Chapter 2.3.1 --- Confidentiality --- p.10Chapter 2.3.2 --- Integrity --- p.12Chapter 2.3.3 --- Availability --- p.12Chapter 2.4 --- Support of eBusiness --- p.13Chapter 3 --- Webservices for e-Government - A Marriage for Interoperability --- p.15Chapter 4 --- A Webservices Based eGovernment Framework --- p.17Chapter 4.1 --- System Component Model --- p.17Chapter 4.2 --- System Access Model --- p.18Chapter 4.3 --- Security Model --- p.20Chapter 4.3.1 --- Access Right Model --- p.20Chapter 4.3.2 --- Authentication Model --- p.22Chapter 4.4 --- Transaction Model --- p.23Chapter 5 --- eGovernment WebServices Access Control --- p.25Chapter 5.1 --- eGovernment WebService --- p.25Chapter 5.2 --- Request of Access --- p.27Chapter 5.3 --- eGovernment Access Policy --- p.30Chapter 5.3.1 --- Administration Based Policy --- p.32Chapter 5.3.2 --- Legislation Based Policy --- p.33Chapter 6 --- Research in Access Control --- p.38Chapter 6.1 --- Traditional Model --- p.38Chapter 6.2 --- More Advanced Models --- p.39Chapter 6.2.1 --- Role-Based Access Control Model --- p.39Chapter 6.2.2 --- Task-Based Authorisation Control Models --- p.41Chapter 6.2.3 --- Digital Library Authorisation Model --- p.42Chapter 6.3 --- Recent Works --- p.44Chapter 6.4 --- Limitations of the Models --- p.45Chapter 7 --- Proposed Approach --- p.47Chapter 7.1 --- WebService Specific Access Control --- p.48Chapter 7.1.1 --- WebService Access Rules --- p.48Chapter 7.1.2 --- Authorisation Conflict Resolution --- p.50Chapter 7.2 --- Subject Based Access Control --- p.52Chapter 7.2.1 --- Subject Category --- p.52Chapter 7.2.2 --- Subject Access Rules --- p.53Chapter 7.2.3 --- WebService Registration --- p.55Chapter 7.2.4 --- Authorisation Conflict Resolution --- p.56Chapter 7.3 --- The WebServices --- p.57Chapter 7.4 --- Combining Two Level Access Control --- p.57Chapter 7.5 --- Application to Chained WebService Request --- p.58Chapter 7.6 --- Comparison with the Existing Access Control Models --- p.59Chapter 8 --- An Implementation Reference Model --- p.60Chapter 8.1 --- Some Practical Issues --- p.60Chapter 8.1.1 --- Citizen Privacy --- p.60Chapter 8.1.2 --- Trust between eGovernment Systems --- p.61Chapter 8.1.3 --- Authentication --- p.62Chapter 8.2 --- System Architecture --- p.64Chapter 8.2.1 --- eGovernment WebServices Gateway --- p.65Chapter 8.2.2 --- Authentication Engine --- p.66Chapter 8.2.3 --- Access Control Database --- p.66Chapter 8.2.4 --- Access Control Decision Engine --- p.67Chapter 8.2.5 --- A Working Scenario --- p.67Chapter 8.3 --- Implementation --- p.69Chapter 9 --- Evaluation of the Proposed Mechanism --- p.74Chapter 9.1 --- Application Scenarios --- p.75Chapter 9.1.1 --- Citizen Level Access Right --- p.75Chapter 9.1.2 --- Access Means Based Authorisation --- p.76Chapter 9.1.3 --- Access Right Based on Combination of User and Consumer Identity --- p.77Chapter 9.1.4 --- Legislation Based Access Right --- p.78Chapter 9.1.5 --- Joined-up Government --- p.79Chapter 10 --- Conclusion and Future Directions --- p.81References --- p.8

Geração de solicitação de serviço para inspeção e manutenção em máquinas industriais utilizando redes sem fio

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Ciência da ComputaçãoNesta dissertação apresentamos um estudo de caso de aplicação real de rede sem fio, cujo objetivo é a melhoria nas atividades de inspeção e a identificação da necessidade de manutenção em máquinas e equipamentos na área industrial. Fazendo utilização de redes sem fios e de unidades móveis, que se conectam periodicamente a uma rede estruturada, permitimos acesso aos dados em uma base consolidada de acordo com as permissões de cada usuário. Nossa aplicação foi baseada em uma arquitetura cliente/servidor, na qual uma rede sem fio deverá proporcionar acesso direto e flexível a uma base de dados coorporativa, gerando solicitações de serviço e planilhas de inspeção em equipamentos industriais. Os dados disponíveis na rede estruturada são apresentados nas unidades móveis que circulam pela fábrica, através da aplicação vertical desenvolvida. Inspetores de máquinas e mecânicos terão suas tarefas facilitadas devido à disponibilidade dos dados em tempo real e à mobilidade provida pelos palmtops. As rotinas de inspeção e de manutenção industrial, em conjunto com a comunicação sem fio, provêem inovação e agilidade nos setores que utilizam máquinas e equipamentos industriais de médio e grande porte, otimizando as atividades do dia a dia. Utilizando unidades móveis, os usuários terão à sua disposição as solicitações de serviço e as planilhas de atividades semipreenchidas, tendo apenas que completar os campos solicitados ou assinalar os itens indicados. A reintegração destes dados no sistema consolidado é efetuada de maneira rápida através de um sincronizador de dados, descartando a necessidade da entrada de dados manual por parte dos digitadores do sistema e eliminando as planilhas de papel. Concluímos com sucesso nossos objetivos e os nossos resultados finais indicam que obtivemos ganhos com o desempenho das tarefas, economia de papel, otimização de tempo do usuário, a disponibilidade on-line e a segurança dos dados na base consolidada

Component replication in application servers

Three-tier middleware architecture is commonly used for hosting large-scale distributed applications. Typically the application is decomposed into three layers: front-end, middle tier and back-end. Front-end ("Web server") is responsible for handling user interactions and acts as a client of the middle tier, while back-end provides storage facilities for applications. Middle tier (' Application server') is usually the place where all computations are performed, so this layer provides middleware services for transactions, security and so forth. The benefit of this architecture is that it allows flexible configuration such as partitioning and clustering for improved performance and scalability. On this architecture, availability measures, such as replication, can be introduced in each tier in an application specific manner. Among the three tier described above, the availability of the middle tier and the back-end tier are the most important, as these tiers provide the computation and the data for the applications. This thesis investigates how replication for availability can be incorporated within the middle and back-end tiers. The replication mechanisms must guarantee exactly once execution of user request despite failures of application and database servers. The thesis develops an approach that requires enhancements to the middle tier only for supporting replication of both the tiers. The design, implementation and performance evaluation of such a middle tier based replication scheme for multi-database transactions on a widely deployed open source application server (1Boss) are presented.EThOS - Electronic Theses Online ServiceQUE Project, Department of Informatics, ITB, Bandung, IndonesiaGBUnited Kingdo