A TxQoS-aware business transaction framework

In this thesis, we propose a transaction framework to provide comprehensive and flexible transaction support for contract-driven, service-oriented business processes. The research follows the research method outlined below. Initially, a thorough investigation on current state of affairs was made. Afterwards, we carried out a case study, which we utilized to identify the problems that are likely to occur during the execution of business processes. As the result of the solution design, the concepts, scenarios, life cycles, reference architectures, and mechanisms were proposed to address the problems. The design took place on the conceptual level, while the coding/programming and implementation is out of the scope of this thesis. The business-oriented solution design allows for transaction qualities to be specified and guaranteed by a contractual approach named as TxQoS (Transactional Quality of Service). The technology-oriented design enables flexible composition of ATCs (Abstract Transaction Constructs) as a transaction schema to support the execution of complex processes. As the last step of research, we validated the feasibility of our design by a utility study conducted in a large telecom project, which has complex processes that are service-oriented and contract-driven. Finally, we discussed the contributions and limitations of the research. The main contribution of the thesis is the BTF (Business Transaction Framework) that addresses process execution reliability. The TxQoS approach enables the specification of transaction qualities in terms of FIAT (Fluency, Interference, Alternation, Transparency) properties. This businessfriendly approach allows the providers and users to agree on transaction qualities before process execution time. The building blocks of the proposed framework, ATCs, are reusable and configurable templates, and are abstracted and generalized from existing transaction models. The various transaction requirements of sub-processes and process chunks can be represented by corresponding ATCs, which allow for a flexible composition. Integrated, the TxQoS and ATC approaches work together to form a TxQoS-aware business transaction framework

BUILDING RELIABLE AND ROBUST SERVICE-BASED SYSTEMS FOR AUTOMATED BUSINESS PROCESSES

An exciting trend in enterprise computing lies in the integration of applications across an organisation and even between organisations. This allows the provision of services by automated business processes that coordinate business activity among several collaborating organisations. The best successes in this type of integrated distributed system come through use of Web Services and Service-based Architecture, which allow interoperation between applications through open standards based on XML and SOAP. But still, there are unresolved issues when developers seek to build a reliable and robust system. An important goal for the designers of a loosely coupled distributed system is to maintain consistency for each long running business process in the presence of failures and concurrent activities. Our approach to assist the developers in this domain is to guide the developers with the key principles they must consider, and to provide programming models and protocols, which make it easier to detect and avoid consistency faults in service-based system. We start by defining a realistic e-procurement scenario to illustrate the common problems faced by the developers which prevent them from building a reliable and robust system. These problems make it hard to maintain the consistency of the data and state during the execution of a business process in the occurrence of failures and interference from concurrent activities. Through the analysis of the common problems, we identify key principles the developers must consider to avoid producing the common problems. Then based on the key principles, we provide a framework called GAT in the orchestration infrastructure. GAT allows developers to express all the necessary processing to handle deviations including those due to failures and concurrent activities. We discuss the GAT framework in detail with its structure and key features. Using an example taken from part of the e-procurement case study, we illustrate how developers can use the framework to design their business requirements. We also discuss how key features of the new framework help the developers to avoid producing consistency faults. We illustrate how systems based on our framework can be built using today’s proven technology. Finally, we provide a unified isolation mechanism called Promises that is not only applicable to our GAT framework, but also to any applications that run in the service-based world. We discuss the concept, how it works, and how it defines a protocol. We also provide a list of potential implementation techniques. Using some of the implementation techniques we mention, we provide a proof-of-concept prototype system

Technical Challenges of Microservices Migration

The microservices architecture is a recent trend in the software engineering community, with the number of research articles in the field increasing, and more companies adopting the architectural style every year. However, the migration of a monolith to the microservices architecture is an error-prone process with a lack of guidelines for its execution. Also, microservices introduce a lot of different challenges that are not faced when following a monolithic architecture. This work aims to fill some gaps in current microservices research by providing a catalogue of the currently most common challenges of adopting this architectural style, and possible solutions for them. For this reason, a systematic mapping study was executed analysing 54 different articles. Also, 30 industry professionals participated in a questionnaire regarding the topic. Furthermore, a participant observation experiment was performed to retrieve additional industry data. Moreover, one of the identified challenges – distributed transactions management – was further detailed and a solution implemented using the choreographed saga pattern. The solution is publicly available as an open-source project. Finally, multiple experts in the microservices field validated the results of the research and the distributed transactions solution and provided insights regarding the value of this work.A arquitetura de microserviços é uma tendência recente na comunidade de engenharia de software, com o número de artigos publicados sobre o tema a aumentar, assim como o número de empresas a adoptar o estilo arquitetural todos os anos. No entanto, o processo de migração de um monolito para uma arquitetura orientada a microserviços tem um alto potencial de erros, uma vez que existe falta de orientações sobre como conduzir o processo corretamente. Para além disso, os microserviços introduzem muitos desafios diferentes que não são enfrentados no desenvolvimento de um sistema monolitico. Este trabalho pretende preencher algumas destas lacunas na investigação da arquitetura de microserviços através da construção de um catalogo dos principais desafios enfrentados ao adoptar o estilo arquitetural e soluções possíveis para estes. Por este motivo, um systematic mapping study foi desenvolvido, analisando 54 artigos diferentes. Para além disso, 30 profissionais da industria responderam a questionario sobre o tema. Finalmente, para obter dados adicionais da indústria, uma experiência de migração foi realizada e observada de forma ativa. Ainda, um dos desafios identificados – gestão de transações distribuídas – foi detalhado e uma solução implementada usando o padrão de sagas coreografadas. A solução está publicamente disponível como um projecto open-source. Finalmente, vários peritos em microserviços avaliaram os resultados deste trabalho, incluindo a solução desenvolvida para gestão de transações distribuídas, e deram feedback relativamente ao valor deste trabalho

Long Running Transactions Within Enterprise Resource Planning Systems

Recently, one of the major problems in various countries is the management of complicated organisations to cope with the increasingly competitive marketplace. This problem can be solved using Enterprise Resource Planning (ERP) systems which can offer an integrated view of the whole business process within an organisation in real-time. However, those systems have complicated workflow, are costly to be analysed to manage the whole business process in those systems. Thus, Long Running Transaction (LRTs) models have been proposed as optimal solutions, which can be used to simplify the analysis of ERP systems workflow to manage the whole organiational process and ensure that completed transactions in a business process are not processed in any other process. Practically, LRTs models have various problems, such as the rollback and check-pointing activities. This led to the use of Communication Closed Layers (CCLs) for decomposing processes into layers to be analysed easily using sequential programs. Therefore, the purpose of this work is to develop an advanced approach to implement and analyse the workflow of an organisation in order to deal with failures in Long Running Transaction (LRTs) within Enterprise Resource Planning (ERP) systems using Communication Closed Layers (CCLs). Furthermore, it aims to examine the possible enhancements for the available methodology for ERP systems based on studying the LRT suitability and applicability to model the ERP workflows and offer simple and elegant constructs for implementing those complex and expensive ERP workflow systems. The implemented model in this thesis offers a solution for two main challenges; incompatibilities that result from the application of transitional transaction processing concepts to the ERP context and the complexity of ERP workflow. The first challenge is addressed based on offering new semantics to allow modelling of concepts, such as rollbacks and check-points through various constraints, while the second is addressed through the use of the Communication Closed Layer (CCL) approach. The implemented computational reconfigurable model of an ERP workflow system in this work is able to simulate real ERP workflow systems and allows obtaining more understanding of the use of ERP system in enterprise environments. Moreover, a case study is introduced to evaluate the application of the implemented model using three scenarios. The conducted evaluation stage explores the effectiveness of executable ERP computational models and offers a simple methodology that can be used to build those systems using novel approaches. Based on comparing the current model with two previous models, it can be concluded that the new model outperforms previous models based on benefiting from their features and solving their limitations which make them inappropriate to be used in the context of ERP workflow models

A new approach to reversible computing with applications to speculative parallel simulation

In this thesis, we propose an innovative approach to reversible computing that shifts the focus from the operations to the memory outcome of a generic program. This choice allows us to overcome some typical challenges of "plain" reversible computing. Our methodology is to instrument a generic application with the help of an instrumentation tool, namely Hijacker, which we have redesigned and developed for the purpose. Through compile-time instrumentation, we enhance the program's code to keep track of the memory trace it produces until the end. Regardless of the complexity behind the generation of each computational step of the program, we can build inverse machine instructions just by inspecting the instruction that is attempting to write some value to memory. Therefore from this information, we craft an ad-hoc instruction that conveys this old value and the knowledge of where to replace it. This instruction will become part of a more comprehensive structure, namely the reverse window. Through this structure, we have sufficient information to cancel all the updates done by the generic program during its execution. In this writing, we will discuss the structure of the reverse window, as the building block for the whole reversing framework we designed and finally realized. Albeit we settle our solution in the specific context of the parallel discrete event simulation (PDES) adopting the Time Warp synchronization protocol, this framework paves the way for further general-purpose development and employment. We also present two additional innovative contributions coming from our innovative reversibility approach, both of them still embrace traditional state saving-based rollback strategy. The first contribution aims to harness the advantages of both the possible approaches. We implement the rollback operation combining state saving together with our reversible support through a mathematical model. This model enables the system to choose in autonomicity the best rollback strategy, by the mutable runtime dynamics of programs. The second contribution explores an orthogonal direction, still related to reversible computing aspects. In particular, we will address the problem of reversing shared libraries. Indeed, leading from their nature, shared objects are visible to the whole system and so does every possible external modification of their code. As a consequence, it is not possible to instrument them without affecting other unaware applications. We propose a different method to deal with the instrumentation of shared objects. All our innovative proposals have been assessed using the last generation of the open source ROOT-Sim PDES platform, where we integrated our solutions. ROOT-Sim is a C-based package implementing a general purpose simulation environment based on the Time Warp synchronization protocol

Model Based Security Testing for Autonomous Vehicles

The purpose of this dissertation is to introduce a novel approach to generate a security test suite to mitigate malicious attacks on an autonomous system. Our method uses model based testing (MBT) methods to model system behavior, attacks and mitigations as independent threads in an execution stream. The threads intersect at a rendezvous or attack point. We build a security test suite from a behavioral model, an attack type and a mitigation model using communicating extended finite state machine (CEFSM) models. We also define an applicability matrix to determine which attacks are possible with which states. Our method then builds a comprehensive test suite using edge-node coverage that allows for systematic testing of an autonomous vehicle

GUISET: A CONCEPTUAL DESIGN OF A GRID-ENABLED PORTAL FOR E-COMMERCE ON-DEMAND SERVICES

Conventional grid-enabled portal designs have been largely influenced by the usual functional requirements such as security requirements, grid resource requirements and job management requirements. However, the pay-as-you-use service provisioning model of utility computing platforms mean that additional requirements must be considered in order to realize effective grid-enabled portals design for such platforms. This work investigates those relevant additional requirements that must be considered for the design of grid-enabled portals for utility computing contexts. Based on a thorough review of literature, we identified a number of those relevant additional requirements, and developed a grid-enabled portal prototype for the Grid-based Utility Infrastructure for SMME-enabling Technology (GUISET) initiative – a utility computing platform. The GUISET portal was designed to cater for both the traditional grid requirements and some of the relevant additional requirements for utility computing contexts. The result of the evaluation of the GUISET portal prototype using a set of benchmark requirements (standards) revealed that it fulfilled the minimum requirements to be suitable for the utility context