SUMMARYScience gateways are digital interfaces to advanced technologies that support science/engineering research/ education. Frequently implemented as Web and mobile applications, they provide access to community resources such as software, data, collaboration tools, instrumentation, and high-performance computing. We anticipate opportunities for growth within a fragmented community. Through a large-scale survey, we measured the extent and characteristics of the gateway community (reliance on gateways and nature of existing resources) to understand useful services and support for builders and users. We administered an online survey to nearly 29,000 principal investigators, senior administrators, and people with gateway affiliations. Nearly 5000 respondents represented diverse expertise and geography. The majority of researchers/educators indicated that specialized online resources were important to their work. They choose technologies by asking colleagues and looking for documentation, demonstrated reliability, and technical support; adaptability via customizing or open-source standards was another priority. Research groups commonly provide their own resources, but public/academic institutions and commercial services also provide substantial offerings. Application creators and administrators welcome external services providing guidance such as technology selection, sustainability planning, evaluation, and specialized expertise (e.g., quality assurance and design). Technologies are diverse, so flexibility and ongoing community input are essential, as is offering specific, easy-to-access training, community support, and professional development.

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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.

Provenance about workflow executions and data derivations in scientific applications help estimate data quality, track resources, and validate in silico experiments. The Karma provenance framework provides a means to collect workflow, process, and data provenance from data-driven scientific workflows and is used in the Linked Environments for Atmospheric Discovery (LEAD) project. This article presents a performance analysis of the Karma service as compared against the contemporary PReServ provenance service. Our study finds that Karma scales exceedingly well for collecting and querying provenance records, showing linear or sub-linear scaling with increasing number of provenance records and clients when tested against workloads in the order of 10,000 application-service invocations and over 36 concurrent clients.

Abstract-This paper provides an overview of the Apache Airavata software system for science gateways. Gateways use Airavata to manage application and workflow executions on a range of backend resources (grids, computing clouds, and local clusters). Airavata's design goal is to provide component abstractions for major tasks required to provide gateway application management. Components are not directly accessed but are instead exposed through a client Application Programming Interface. This design allows gateway developers to take full advantage of Airavata's capabilities, and Airavata developers (including those interested in middleware research) to modify Airavata's implementations and behavior. This is particularly important as Airavata evolves to become a scalable, elastic "platform as a service" for science gateways. We illustrate the capabilities of Airavata through the discussion of usage vignettes. As an Apache Software Foundation project, Airavata's open community governance model is as important as its software base. We discuss how this works within Airavata and how it may be applicable to other distributed computing infrastructure and cyberinfrastructure efforts.

SUMMARYThe Linked Environments for Atmospheric Discovery (LEAD) Portal is a science application portal designed to enable effective use of Grid resources in exploring mesoscale meteorological phenomena. The aim of the LEAD Portal is to provide a more productive interface for doing experimental work by the meteorological research community, as well as bringing weather research to a wider class of users, meaning pre-college students in grades 6-12 and undergraduate college students. In this paper, we give an overview of the LEAD project and the role that LEAD portal is playing in reaching its goals. We then describe the various technologies we are using to bring powerful and complex scientific tools to educational and research users. These technologies-a fine-grained capability based authorization framework, an application service factory toolkit, and a Web services-based workflow execution engine and supporting tools-enable our team to deploy these once inaccessible, stovepipe scientific codes onto a Grid where they can be collectively utilized.

Abstract.Grid computing is about allocating distributed collections of resources including computers, storage systems, networks and instruments to form a coherent system devoted to a "virtual organization" of users who share a common interest in solving a complex problem or building an efficient agile enterprise. Service oriented architectures have emerged as the standard way to build Grids. This paper provides a brief look at the Open Grid Service Architecture, a standard being proposed by the Global Grid Forum, which provides the foundational concepts of most Grid systems. Above this Grid foundation is a layer of applicationoriented services that are managed by workflow tools and "science gateway" portals that provide users transparent access to the applications that use the resources of a Grid. In this paper we will also describe these Gateway framework services and discuss how they relate to and use Grid services.

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