Implementing E-transactions with asynchronous replication

An e-Transaction is one that executes exactly-once despite failures. This paper describes a distributed protocol that implements the abstraction of e-Transactionsin three-tier architectures. Three-tier architectures are typically Internet-oriented architectures, where the end-user interacts with front-end clients (e.g., browsers) that invoke middle-tier application servers (e.g., web servers) to access back-end databases. We implement the e-Transaction abstraction using an asynchronous replication scheme that preserves the three-tier nature of the architecture and introduces a very acceptable overhead with respect to unreliable solutions

Automatic generation of AMF compliant configurations

Nowadays, the demand for robust, reliable, and dependable telecommunication systems is higher than ever. End users expect services to be delivered with minimal to no interruption especially in cases where the effect of service outage can have catastrophic consequences such as loss of human lives and monetary losses. Examples of such applications include air traffic control and navigation systems, or systems that perform money transfer transactions such as VISA. Systems are considered highly available if they are up and running 99.999% of the time. One solution to sustain such availability is for such systems to be deployed on specific middleware that allow the redundancy of the system components to ensure the availability of services they provide. However, most existing platforms are proprietary and platform dependent. The goal of the Service Availability Forum (SAF) is to develop open specifications that aim to standardize the interface between the applications and the middleware from one side and the middleware and the underlying hardware from the other side. SAF specifications have also been developed to allow highly available applications to be built using commercial off-the-shelf components. A key component of SAF is the Availability Management Framework (AMF), which is the middleware part responsible for managing the redundant resources of applications and therefore enables high availability. AMF, however, requires a certain organization and groupings of those components known as an AMF configuration. Creating AMF configurations manually tends to be very difficult, error prone and sometimes impossible when the number of components forming the application and the cluster hosting the application is considerably high, which is the case for most real-world telecommunication systems. In this thesis, we devise a solution for automatically generating AMF compliant configurations for applications. The proposed solution encompasses two techniques that vary depending on the way AMF entities are handled. We have implemented both approaches and applied one of them to a case study to demonstrate the applicability of our solutio

Intelligent Management of Virtualised Computer Based Workloads and Systems

Managing the complexity within virtualised IT infrastructure platforms is a common problem for many organisations today. Computer systems are often highly consolidated into a relatively small physical footprint compared with previous decades prior to late 2000s, so much thought, planning and control is necessary to effectively operate such systems within the enterprise computing space. With the development of private, hybrid and public cloud utility computing this has become even more relevant; this work examines how such cloud systems are using virtualisation technology and embedded software to leverage advantages, and it uses a fresh approach of developing and creating an Intelligent decision engine (expert system). Its aim is to help reduce the complexity of managing virtualised computer-based platforms, through tight integration, high-levels of automation to minimise human inputs, errors, and enforce standards and consistency, in order to achieve better management and control. The thesis investigates whether an expert system known as the Intelligent Decision Engine (IDE) could aid the management of virtualised computer-based platforms. Through conducting a series of mixed quantitative and qualitative experiments in the areas of research, the initial findings and evaluation are presented in detail, using repeatable and observable processes and provide detailed analysis on the recorded outputs. The results of the investigation establish the advantages of using the IDE (expert system) to achieve the goal of reducing the complexity of managing virtualised computer-based platforms. In each detailed area examined, it is demonstrated how using a global management approach in combination with VM provisioning, migration, failover, and system resource controls can create a powerful autonomous system

A Model Based Framework for Service Availability Management

High availability of services is an important requirement in several domains, including mission critical systems. The Service Availability Forum (SA Forum) is a consortium of telecommunications and computing companies that defines standard middleware solutions for high availability. Availability Management Framework (AMF) manages the high availability of services by coordinating their application components according to redundancy models. To protect these services, AMF requires a configuration, i.e. a representation of the organization of the logical entities composing an application under its control. AMF configuration design is error-prone and tedious if done manually, due to the complexity of the AMF domain. This PhD thesis explores the effective design and analysis of AMF configurations, proposing a model-based management framework that facilitates this process. We propose a domain-specific modeling language that captures AMF domain concepts, relationships, and constraints, facilitating the management of AMF configurations. We define this language by extending UML through its profiling mechanism, capturing the concepts of AMF configurations and the description of the software for which the configuration will be generated. We introduce a new approach for the automatic generation of AMF configurations based on our UML profile using model transformation techniques. This approach consists of a set of transformations from the software description entities into AMF configurations while satisfying the requirements of the services to be provided as well as the constraints of the deployment infrastructure. We also propose a third-party AMF configuration validation approach consisting of syntactical and semantic validations. Syntactical validation checks the well-formedness of third-party configurations by validating them against AMF standard specification requirements captured in our UML profile. Semantic validation focuses on ensuring the runtime protection of services at configuration time (the SI-Protection problem). SI-Protection has combinatorial aspects and results in an NP-hard problem for most redundancy models, which we have tackled by devising a heuristic-based method, overcoming its complexity. We present proofs of concepts by using different available technologies: IBM Rational Software Architect (RSA) for implementing our UML profiles, Eclipse environment for developing a prototype tool for validating third-party configurations, and Atlas Transformation Language (ATL) for developing a prototype implementation of our model-based configuration generation approach