Web Services for MPI-Based Parallel Applications on a Rocks Cluster

Web service interfaces are considered as one of the critical components of a Service-Oriented Architecture (SOA) and they represent contracts between web service providers and clients (subscribers). These interfaces are frequently modified to meet new requirements. However, these changes in a web service interface typically affect the systems of its subscribers. Thus, it is important for subscribers to estimate the risk of using a specific service and to compare its evolution to other services offering the same features in order to reduce the effort of adapting their applications in the next releases. In addition, the prediction of interface changes may help web service providers to better manage available resources (e.g. programmers’ availability, hard deadlines, etc.) and efficiently schedule required maintenance activities to improve the quality. In this paper, we propose to use machine learning, based on Artificial Neuronal Networks, for the prediction of the evolution of Web services interface design. To this end, we collected training data from quality metrics of previous releases from 6 Web services. The validation of our prediction techniques shows that the predicted metrics value, such as number of operations, on the different releases of the 6 Web services were similar to the expected ones with a very low deviation rate. In addition, most of the quality issues of the studied Web service interfaces were accurately predicted, for the next releases, with an average precision and recall higher than 82 %. The survey conducted with active developers also shows the relevance of prediction technique for both service providers and subscribers.

With the rapid development of Internet, Web Service technology is gradually applied to many areas of life. The security problems occurred in practical applications of Web Service has received more and more attention from the public. Aiming at the security problems existing in the application process of Web Service, a secure real-time internal and external network data exchange method based on Web Service protocol is proposed in this paper, it is agreed that the external network only allows data exchange with the internal network through the Web Service interface, that is, the internal network starts the Web Service service, the external network accesses the service, and then obtains the internal network data or informs the internal network for business processing. Web attack detection is put to the front end to ensure maximum security of Web Service system, which can meet the requirements of more secure and robust web applications while guaranteeing the business security of visitors.

We present a language for specifying web service interfaces. A web service interface puts three kinds of constraints on the users of the service. First, the interface specifies the methods that can be called by a client, together with types of input and output parameters; these are called signature constraints. Second, the interface may specify propositional constraints on method calls and output values that may occur in a web service conversation; these are called consistency constraints. Third, the interface may specify temporal constraints on the ordering of method calls; these are called protocol constraints. The interfaces can be used to check, first, if two or more web services are compatible, and second, if a web service A can be safely substituted for a web service B. The algorithm for compatibility checking verifies that two or more interfaces fulfill each others' constraints. The algorithm for substitutivity checking verifies that service A demands fewer and fulfills more constraints than service B.

It is common that multiple Web services coordinate to achieve a common goal. If two Web services happen to reside on the same runtime system, it is inefficient to communicate via Web services interface. This research proposes our short circuit switch (SCS), which is an intelligent Web services discovery and invocation engine that can be attached to deployed Web services. Our preliminary empirical experience shows that our short circuit switch engine exhibits high performance.

SOA and Web Services allow to easily expose business functions to build larger distributed systems. However, legacy systems – mostly in COBOL – are left aside unless applying a migration approach. Main approaches are: direct and indirect migration. The former implies to wrap COBOL programs with a thin layer of a Web Service oriented language/platform. The latter needs reengineering COBOL functions to a modern language/platform. In a previous work, we presented an intermediate approach based on direct migration where developed Web Services are later refactored to improve their interfaces quality. Refactorings mainly capture good practices inherent to indirect migration. In this paper, we measure the complexity of Web Services’ interfaces generated by the three approaches. Both comprehension and interoperability can be affected according to the service interface complexity level. We apply a metric suite (by Baski & Misra) to measure complexity on services interfaces – i.e., WSDL documents. Migrations of two real COBOL systems upon the three approaches were compared on the complexity level of the generated WSDL documents.

Web service architectures have gained popularity in recent years within the scientific grid research community. One reason for this is that web services allow software and services from various organizations to be combined easily to provide integrated and distributed applications. However, most applications developed and used by scientific communities are not web-service-oriented, and there is a growing need to integrate them into grid applications based on service-oriented architectures. In this paper, we describe a framework that allows scientists to provide a web service interface to their existing applications as web services without having to write extra code or modify their applications in any way. In addition, application providers do not need to be experts in web services standards, such as Web Services Description Language, Web Services Addressing, Web Services Security, or secure authorization, because the framework automatically generates these details. The framework also enables users to discover these application services, interact with them, and compose scientific workflows from the convenience of a grid portal.

Speeding up the communications on a cluster using MPI by means of Software Defined Networks

Currently, scientific application developers often configure available application components into a workflow of tasks that they can submit for execution on distributed systems. In this chapter, we present the Abstract Workflow Description Language (AWDL) for describing scientific workflow applications at a high level of abstraction. AWDL has been designed such that the user can concentrate on specifying scientific applications without dealing with either the complexity of distributed systems or any specific implementation technology (e.g., Web Services). AWDL is an XML-based language which allows a programmer to define a graph of activities that refer mostly to computational tasks. Activities are connected by control and data flow links. A rich set of control flow constructs (compound activities) is provided to simplify the specification of scientific workflow applications which includes dag, for, while, and alt. In addition, AWDL programmers can specify high-level constraints and properties for activities and data flow links which may be useful for underlying runtime systems to steer and optimize workflow executions. AWDL is the main interface to the ASKALON development and runtime environment for workflows on distributed systems and has been applied to numerous real-world scientific workflow applications. We describe a material science workflow that has been successfully ported to a distributed infrastructure based on the AWDL specification.

Today, the task of running and coordinating a scientific application across several administrative domains is extremely complex. As an example, the most popular tool for scientific applications, MPI, is not designed to address firewall limitations or data heterogeneity, even if its extensions deal with some of these problems. In this paper, we design a new approach to run a scientific application in a distributed environment, when data and computing power are scattered across the Web: Web services can be used to tunnel computation and data migration. We show that a very simple mapping exists between MPI primitives and the Web service infrastructure. We are currently designing a framework, based on Web services, which will implement the main MPI primitives: this way an MPI application could be run on any platform supporting Web services.

In this paper we propose a service-oriented architecture for data exchanging between applications using heterogonous databases. Heterogeneous data makes it difficult to be shared across organizations. In these organizations, data is often produced with diverse applications relying on a mix of software and information systems. Each application uses its individual system to increase efficiency, but sharing data across the enterprise is a near impossibility. We discuss a service-oriented architecture of using web services which has been adopted for integrating diverse repositories of data. Based on our practical tests, the proposed framework proved to be an efficient solution for sharing and accessing to Heterogeneous data.

A web service interface contains information about the names of the operations that can be invoked on the service and the input and output parameters of these operations. This information is not enough to facilitate service developer and consumer in understanding the behavior of the service. In the context of RESTful web services, the requirements of RESTful interface should also be met that are not fulfilled by just advertising the allowed operations on the resources. In addition, RESTful services take hypermedia as an engine of application states. Such services are defined to be at level 3 of Richardson Maturity Model(RMM). In this paper, we present an approach to model the structural and behavioral interface of a RESTful web service using UML class and UML protocol diagrams. These models lead to RESTful interfaces that conform to level 3 of RMM and describe the behavior of operations in terms of preconditions and post-conditions. These models facilitate the authentication mechanism and provide clear mapping to HTTP requests and responses. The generated contracts of methods can be published in an extended version of the WADL language and also used for documentation, stub generation, testing and monitoring purposes.

Spatio-temporal modelling of individual exposure to air pollution and its uncertainty

Like the case of any software, Web Services (WSs) developers could introduce anti-patterns due to the lack of experience and badly-planned changes. During the last decade, search-based approaches have shown their outperformance over other approaches mainly thanks to their global search ability. Unfortunately, these approaches do not consider the uncertainty of class labels. In fact, two experts could be uncertain about the smelliness of a particular WS interface but also about the smell type. Currently, existing works reject uncertain data that correspond to WSs interfaces with doubtful labels. Motivated by this observation and the good performance of the possibilistic K-NN classifier in handling uncertain data, we propose a new evolutionary detection approach, named Web Services Anti-patterns Detection and Identification using Possibilistic Optimized K-NNs (WS-ADIPOK), which can cope with the uncertainty based on the Possibility Theory. The obtained experimental results reveal the merits of our proposal regarding four relevant state-of-the-art approaches.

The analysis of parallel scientific applications allows us to understand their computational and communication behavior. One way of obtaining performance information is through performance tools. One such tool is parallel application signatures for performance prediction (PAS2P), based on parallel application repeatability, focusing on performance analysis and prediction. The same resources that execute the parallel application are used to perform its analysis, creating a machine independent model of the application and identifying its common patterns. However, the analysis is costly in terms of execution time due to the high number of synchronization communications performed by PAS2P, degrading performance as the number of processes increases. To solve this problem, we propose a model that reduces data dependency between processes, reducing the number of communications performed by PAS2P in the analysis stage and taking advantage of the characteristics of single program, multiple sata applications. Our analysis proposal allows us to decrease the analysis time by 29 times when the application scales to 256 processes, while keeping error levels below 11% in the runtime prediction. It is important to mention that the analysis time is not considerably affected by increasing the number of application processes.

An important part of enabling the future information infrastructure is to provide convenient services for application users that make such an environment highly functional and easy to use for the non-expert. In other words, the scientist should be able to focus on the science but should have sophisticated tools at hand that enable new and enhanced modalities in which science can be performed. We describe a general architecture that provides access to scientific applications. We demonstrate how such services can interact with each other and be reused by the scientific application architect to orchestrate Grid services. Our architecture is implemented by reusing concepts, infrastructures, and middleware from Web and Grid services, as well as from the newest Globus Toolkit and the Java CoG Kit. We apply our general architecture to a specific application: Active Thermochemical Tables. This application demonstrates a number of interesting and future-oriented uses, such as the need for batch processing, interactive and collaborative steering, use of multiple platforms,visualization through large displays, and access via a portal framework. Besides the innovative use of the Grid and Web services, we also provide a novel algorithmic contribution to scientific disciplines that use thermochemical tables. Specifically, we modified the original approach to constructing thermochemical tables to include an iterative process of refinement leading to increased accuracy. We have designed a variety of access environments including a shell, a Grid desktop, and a portal for accessing the set of services provided, which include the display of network dependencies between the reactions a chemist may be interested in and interactive querying of associated species data. Modalities that need to be supported are the protection of intellectual property, the creation of metadata and information shared with and gathered by the community, and easy access to the service by the application scientists.