Rob Allan

Evaluation of BPEL to Scientific Workflows

We investigate the requirements of Scientific Workflows in context of the Business Process Execution Language for Web Services (BPEL4WS/ BPEL. The complexity, unpredictability and inter-dependency of the components in a scientific workflow often demand flexibility in a workflowlanguage in order to support; 1) exception handling, 2) recovery from uncertain situations, 3) user interactions to facilitate interactive steering and monitoring, 4) dynamism to adapt to the changing environment, 5) compensation handling to roll back, and 6) support for dynamic selection of services. We illustrate these requirements with examples taken from a real scientific workflow; the e-HTPX project for high throughput protein crystallography. In this paper, we discuss the application of BPEL, which is widely regarded as the de-facto standard for orchestrating Web Services for Business Workflows with a large set of features to support complex requirements. These features, along with other standard tools, can be adapted to fulfill the requirements of Scientific Workflows.

ShibGrid: Shibboleth Access for the UK National Grid Service

This paper presents work undertaken to integrate the future UK national Shibboleth infrastructure with the UKs National Grid Service (NGS). Our work, ShibGrid, provides both transparent authentication for portal based Grid access and a credential transformation service for users of other Grid access methods. The ShibGrid support for portal-based transparent Grid authentication is provided as a set of standards-based drop-in modules which can be used with any project portal as well as the NGS project in which they are initially deployed. The ShibGrid architecture requires no changes to the UK national Shibboleth authentication infrastructure or the NGS security infrastructure and provides access for users both with and without UK e-Science certificates. In addition to presenting both the architecture of Shib- Grid and its implementation, we additionally place the ShibGrid project within the context of other efforts to integrate Shibboleth with Grids.

Integration of Existing Grid Tools in Sakai VRE

The integration of existing grid tools into the Sakai VRE (virtual research environment) is discussed in this paper. In particular we describe the integration of the business logic and JSR 168 compliant portlets through presentation-oriented Web services, via WSRP (Web services for remote portlets). A set of JSR 168 compliant portlets were developed for the UK NGS (National Grid Service) portal and have been published using WSRP4J and consumed within Sakai successfully, which proves re-use of portlets as Web components is a practical option. With the help of the WSRP consumer tool, the Sakai VRE has been successfully extended to support the JSR 168 specification

Using the Sakai collaborative toolkit in e-Research applications

The Sakai Project (http://www.sakaiproject.org) is developing a collaborative environment that provides capabilities that span teaching and learning as well as e‐Research applications. By exploiting the significant requirements overlap in the collaboration space between these areas, the Sakai community can harness significant resources to develop an increasingly rich set of collaborative tools. While collaboration is a significant element of many e‐Research projects, there are many other important elements including portals, data repositories, compute resources, special software, data sources, desktop applications, and content management/e‐Publication. The successful e‐Research projects will find ways to harness all of these elements to advance their science in the most effective manner. It is critical to realize that there is not a single software product that can meet the requirements for such a rich e‐Research effort. Realizing that multiple elements must be integrated together for best effect leads us to focus on understanding the nature of integration and working together to improve the cross‐application integration. This leads us not to drive towards a single toolkit (such as Sakai or Globus), but instead to a meta‐toolkit containing well‐integrated applications. When considering a technology for use, perhaps the most important aspect of that technology is how well it integrates with other technologies. Copyright

Web-Based Virtual Research Environments (VRE): Support Collaboration in e-Science

Interdisciplinary challenges in research today require increasingly cooperation among researchers. The demand for building up virtual research environments (VRE) becomes more and more urgent than ever before. Built on top of Web, VRE systems aim at supporting research activities with much more efficient methods for sharing data and knowledge bases. In this paper, we present our recent work on development of a general-purpose VRE system by extending Sakai, an advanced collaboration and learning platform, with tools for accessing Microsoft exchange server through WebDAV, integrating existing grid tools to access remote computing and data grid resources via Web services for remote portlets (WSRP), and managing documents to help organising workshops and conferences

High Performance Computing

■ Expert analysis of interdisciplinary problems in physics, mathematics and high-performance computing. ■ Application of mathematical modeling in physics with particular focus to area of continuum mechanics. ■ Expert knowledge of mathematical analysis for problems in continuum physics and related areas. ■ Expertise in theory of numerical methods and their application in modern HPC environments. ■ Contact with wide network of local and international experts (EU-MATHS-IN, Nečas Center for Mathematical Modeling). ■ Development of models for complex materials from the basic principles to an eff icient numerical solution. ■ Consultancy services in the fi eld of mathematical modeling, analysis, numerical soft ware and calculations. EXPERTISEOn the way to Exascale, programmers face the increasing challenge of having to support multiple hardware architectures from the same code base. At the same time, portability of code and performance are increasingly difficult to achieve as hardware architectures are becoming more and more diverse. Today’s heterogeneous systems often include two or more completely distinct and incompatible hardware execution models, such as GPGPU’s, SIMD vector units, and general purpose cores which conventionally have to be programmed using separate tool chains representing non-overlapping programming models. The recent revival of interest in the industry and the wider community for the C++ language has spurred a remarkable amount of standardization proposals and technical specifications in the arena of concurrency and parallelism. This recently includes an increasing amount of discussion around the need for a uniform, higher-level abstraction and programming model for parallelism in the C++ standard targeting heterogeneous and distributed computing. Such an abstraction should perfectly blend with existing, already standardized language and library features, but should also be generic enough to support future hardware developments. In this paper, we present the results from developing such a higher-level programming abstraction for parallelism in C++ which aims at enabling code and performance portability over a wide range of architectures and for various types of parallelism. We present and compare performance data obtained from running the well-known STREAM benchmark ported to our higher level C++ abstraction with the corresponding results from running it natively. We show that our abstractions enable performance at least as good as the comparable base-line benchmarks while providing a uniform programming API on all compared target architectures. c

Top Ten Questions To Design A Successful Grid Portal

With the enhancement of Grid application, Grid portal provides a unique interface for end-users to access distributed resources and are used widely in Knowledge Grid, e-Science, e-learning and e-business. A successful Grid portal relies on many factors. This paper focuses primarily on the design aspects of a successful Grid portal implementation. Ten questions of designing Grid portal are discussed in no particular order. The questions detail the key considering areas of Grid portal architecture, Grid portal contents, portal security, reusability, software design, management and programming test.

Organization of grid resources in communities

Locating suitable resources within a Grid is a computationally intensive process, with no guarantee of quality and suitability of the discovered resources. An alternative approach is a middleware to categorize resources based on the services they provide - leading to the interaction of peers with common goals to form societies/communities. The middleware organizing resources in different communities is suggested to be useful for efficient resource discovery. The communities can be adaptive in nature and evolve based on changes in their operating environment -- such as changes in neighboring communities and user requirements. We have implemented JXTA prototype to illustrate the concepts of community formation in which Peers offering different services can be grouped together based on different criteria.

A workflow portal supporting multi-language interoperation and optimization

In this paper we present a workflow portal for Grid applications, which supports different workflow languages and workflow optimization. We present an XSLT converter that converts from one workflow language to another and enables the interoperation between different workflow languages. We discuss strategies for choosing the optimal service from several semantically equivalent Web services in a Grid application. The dynamic selection of Web services involves discovering a set of semantically equivalent services by filtering the available services based on metadata, and selecting an optimal service based on real‐time data and/or historical data recorded during prior executions. Finally, we describe the framework and implementation of the workflow portal which aggregates different components of the project using Java portlets. Copyright

Plug‐and‐play remote portlet publishing

Web Services for Remote Portlets (WSRP) is gaining attention among portal developers and vendors to enable easy development, increased richness in functionality, pluggability, and flexibility of deployment. Whilst currently not supporting all WSRP functionalities, open‐source portal frameworks could in future use WSRP Consumers to access remote portlets found from a WSRP Producer registry service. This implies that we need a central registry for the remote portlets and a more expressive WSRP Consumer interface to implement the remote portlet functions. This paper reports on an investigation into a new system architecture, which includes a Web Services repository, registry, and client interface. The Web Services repository holds portlets as remote resource producers. A new data structure for expressing remote portlets is found and published by populating a Universal Description, Discovery and Integration (UDDI) registry. A remote portlet publish and search engine for UDDI has also been developed. Finally, a remote portlet client interface was developed as a Web application. The client interface supports remote portlet features, as well as window status and mode functions. Copyright