Implementation of the optimizer of SOA system deployment architecture

Optimization of business processes in SOA systems has been done using three separate types of methods: Resource Allocation, Service Scheduling and Service Composition. All three may influence each other, so the new method has been proposed to find an optimal combination of those three. It is based on a genetic algorithm that uses a simulator of the SOA system to evaluate solutions. The article describes a model for the optimization criteria for such solutions. Subsequently, some basic concepts used to implement the simulator and optimizer have been presented. Finally, the performance results of the optimizer have been described, including the conclusions on how they might be improved.Optimization of business processes in SOA systems has been done using three separate types of methods: Resource Allocation, Service Scheduling and Service Composition. All three may influence each other, so the new method has been proposed to find an optimal combination of those three. It is based on a genetic algorithm that uses a simulator of the SOA system to evaluate solutions. The article describes a model for the optimization criteria for such solutions. Subsequently, some basic concepts used to implement the simulator and optimizer have been presented. Finally, the performance results of the optimizer have been described, including the conclusions on how they might be improved

Workflow scheduling for service oriented cloud computing

Service Orientation (SO) and grid computing are two computing paradigms that when put together using Internet technologies promise to provide a scalable yet flexible computing platform for a diverse set of distributed computing applications. This practice gives rise to the notion of a computing cloud that addresses some previous limitations of interoperability, resource sharing and utilization within distributed computing. In such a Service Oriented Computing Cloud (SOCC), applications are formed by composing a set of services together. In addition, hierarchical service layers are also possible where general purpose services at lower layers are composed to deliver more domain specific services at the higher layer. In general an SOCC is a horizontally scalable computing platform that offers its resources as services in a standardized fashion. Workflow based applications are a suitable target for SOCC where workflow tasks are executed via service calls within the cloud. One or more workflows can be deployed over an SOCC and their execution requires scheduling of services to workflow tasks as the task become ready following their interdependencies. In this thesis heuristics based scheduling policies are evaluated for scheduling workflows over a collection of services offered by the SOCC. Various execution scenarios and workflow characteristics are considered to understand the implication of the heuristic based workflow scheduling

Ensuring Service Level Agreements for Composite Services by Means of Request Scheduling

Building distributed systems according to the Service-Oriented Architecture (SOA) allows simplifying the integration process, reducing development costs and increasing scalability, interoperability and openness. SOA endorses the reusability of existing services and aggregating them into new service layers for future recycling. At the same time, the complexity of large service-oriented systems negatively reflects on their behavior in terms of the exhibited Quality of Service. To address this problem this thesis focuses on using request scheduling for meeting Service Level Agreements (SLAs). The special focus is given to composite services specified by means of workflow languages. The proposed solution suggests using two level scheduling: global and local. The global policies assign the response time requirements for component service invocations. The local scheduling policies are responsible for performing request scheduling in order to meet these requirements. The proposed scheduling approach can be deployed without altering the code of the scheduled services, does not require a central point of control and is platform independent. The experiments, conducted using a simulation, were used to study the effectiveness and the feasibility of the proposed scheduling schemes in respect to various deployment requirements. The validity of the simulation was confirmed by comparing its results to the results obtained in experiments with a real-world service. The proposed approach was shown to work well under different traffic conditions and with different types of SLAs

Service Level Agreement Aware Workflow Scheduling

Specifying and monitoring Service Level Agreements (SLA) has been the subject of intensive research. However methods for enforcing SLA have not addressed the specific issues of Composite Web Services. Our work focuses on the problem of ensuring prearranged SLAs for service workflow via SLA Aware Workflow Scheduling (SLAAWS). The novel scheduling algorithm takes into account the workflow structure, utilization of component services and Quality of Service (QoS) obligations defined in SLA. 1