Soumaya Marzouk

Aspect-oriented checkpointing approach of composed web services

This paper proposes a solution for strong mobility of composed Web services. In fact, strong mobility enables a running BPEL process to be migrated from a host to another and to be resumed on the destination host starting from a previous execution state called also checkpoint which avoids the high overhead of restarting the composed Web service in case of interruption of the BPEL process. The proposed solution makes use of Aspect-Oriented Programming (AOP) in order to enable dynamic capture and recovery of a BPEL process state. This will enable the choose, at runtime, of the instant of the checkpoint and the technique for enacting it. Thus, the proposed approach may be used for self-healing and self-adaptivity of composed Web services acting in case of failure or QoS violation. An experimentation has been performed on a Travel agency case study deployed on the AO4BPEL engine. It shows the efficiency and the usability of our approach.

Toward Antifragile Cloud Computing Infrastructures

Abstract Cloud computing systems are rapidly growing in scale and complexity. They are also changing dynamically as a result of dynamic addition and removal of system components, different execution environments, common updates and upgrades, runtime repairs, mobility of devices and more. Such large-scale, complex and dynamic cloud environments are prone to failures and per- formance anomalies. Thus, dependability and resilience in cloud computing are of paramount importance to guarantee availability and reliability of services and application execution, even in the presence of large number of faulty components. Antifragility is the key to such techniques. It proposes that some systems could be strengthened by changes and faults instead of be weakened by them. In contrast to classical resilience methods, antifragile techniques aim to build systems that handle unpredictable and irregular events, while growing and getting stronger. Most of the classical resilience techniques are not sufficient to build highly available cloud infrastructures. In fact, they just resist shocks and stay the same. They should be complemented by some other aspects like learning from failure to built more elastic and stronger cloud infrastructures. This may represent the idea of building antfragile cloud systems. In this paper, we discuss the existing resilience techniques and propose a solution to design antifragile systems in cloud computing environments.

Towards Making WSRF Based Web Services Strongly Mobile

Grid Services became a widely used technology for building service oriented applications. The Web service resource framework (WSRF) is the current standard used for building such services as it describes the way to design and communicate with stateful services. However, deploying Web services on a grid environment raises many challenges such as adapting the Web service to the dynamic change of grid resources performance and availability. Therefore, mechanisms, such as service mobility, may be very helpful for supporting autonomic properties of grid services. In this paper, we propose a solution for WSRF grid services strong mobility allowing services to migrate during their execution while keeping their state consistent. In addition, suspended services will resume their execution starting from the interruption point. To show the feasibility of our approach, we present a case study illustrating the application of our transformation on a WSRF Auction service. We provide then some preliminary evaluations performed on the Globus Toolkit (version4.0).

A serialisation based approach for processes strong mobility

We present in this paper a generic approach for process transformation into strong mobile entity. Our approach is based on processes Serialisation using source code transformation, which generates the source code of a strong mobile process. Our approach is suitable for transforming distributed applications into mobile applications where every process can be migrated independently any time. We applied our approach to Java Thread by designing a grammar describing the generated mobile process code. The evaluation results of generated mobile Threads shows good performances.

A policy-based approach for strong mobility of composed Web services

This paper presents a flexible, portable, and transparent solution for strong mobility of composed Web services relying on policy-oriented techniques. The proposed approach provides a checkpoint solution based on automatic code instrumentation using correct source code transformation rules. This checkpoint technique permits to save the execution state of a mobile orchestration process as well as the execution states of its orchestrated partners. Thus, after migration, only non-executed codes will be resumed. In addition, our approach enables dynamic adaptation of the employed checkpointing and mobility techniques using aspects. For that, we use policies allowing dynamic selection of the used checkpointing and mobility techniques according to the execution context. Moreover, the proposed solution includes a module allowing the determination of the checkpointing interval satisfying QoS requirements. Experimentations show the efficiency of the proposed solution.

A runtime performance analysis for web service-based applications

Runtime performance evaluation is necessary for the continuous QoS (Quality of Service) management of Web service-based applications. The analysis is critical in service provisioning since it allows to detect QoS degradation and to identify its source. However, performance analysis in current applications is usually based on QoS reference values that are manually instrumented and pre-established independently from the execution context. It is inflexible to change. The paper extends our previous research on performance evaluation within a self-healing framework and proposes a novel analysis approach based on automatic generation of QoS reference values. These QoS reference values are generated whenever we start the application execution in a new context. This approach enables the detection of QoS degradation, the identification of its nature (like execution or communication level) and the localization of its cause (as scalability issue, node failure or network overload). The carried out experiments show that the dynamic generated QoS reference values are suitable and their associated analysis results are accurate.

A serialization based approach for strong mobility of shared object

Mobility becomes very important in distributed Computing. Thus, many works deal with process strong mobility, but few of them deal with mobility of shared objects. In this paper, we present a mobility approach based on source code transformation, which allows strong mobile processes to communicate via remote shared objects. This approach enables shared object strong mobility. We demonstrate how both strong mobile processes and strong mobile shared objects can migrate at the same time while maintaining consistency of the application execution. We implemented our approach on Java Threads, using Java RMI. The evaluation of execution times shows that the overhead is very small compared to the original execution time.

Towards Planning Policies for Self-Adaptive Orchestrated Web Services

This paper aims to provide planning policies enabling self-adaptation of composed Web services in case of failure or Quality of Service (QoS) degradation. Therefore, we employ orchestration process mobility using different techniques. And, we propose a set of rules enabling the selection, at runtime, of the mobility techniques according to current execution conditions. These rules are validated through the evaluation of each mobility technique under different execution conditions in order to deduce which technique is more suitable in each condition.

Grid Load Balancing Based on Economic-Driven Control of Demand and Supply of Services

The computing grids make possible to use a huge computing power by aggregating the power of several isolated resources. This concept evolved especially on the idea of resource virtualisation. It is within this framework that we were interested in service oriented grids. We privileged the economic-based resource allocation models. We study the scheduling through a service oriented and market oriented grid. We proposed an architecture for the grid to articulate the different compounds: the consumers, the supplier of services and the brokers. We proposed three algorithms for brokers of grid in order to control the demand an the supply of services on the market where the brokers was in concurrence. We finally compared the three proposals.