Open Grid Forum

Concurrency and Computation:Practice and Experience

Below are abstracts and links to the preliminary papers contained in the Special OGF Issue of the Journal:

Reliability in Grid Computing Systems

In recent years, grid technology has emerged as an important tool for solving compute-intensive problems within the scientific community and in industry. To further the development and adoption of this technology, researchers and practitioners from different disciplines have collaborated to produce standard specifications for implementing large-scale, interoperable grid systems. The focus of this activity has been the Open Grid Forum, but other standards development organizations have also produced specifications that are used in grid systems. To date, these specifications have provided the basis for a growing number of operational grid systems used in scientific and industrial applications. However, if the growth of grid technology is to continue, it will be important that grid systems also provide high reliability. In particular, it will be critical to ensure that grid systems are reliable as they continue to grow in scale, exhibit greater dynamism, and become more heterogeneous in composition. Ensuring grid system reliability in turn requires that the specifications used to build these systems fully support reliable grid services. This study surveys work on grid reliability that has been done in recent years and reviews progress made toward achieving these goals. The survey identifies important issues and problems that researchers are working to overcome in order to develop reliability methods for large-scale, heterogeneous, dynamic environments. The survey also illuminates reliability issues relating to standard specifications used in grid systems, identifying existing specifications that may need to be evolved and areas where new specifications are needed to better support reliability.

The HPC Basic Profile and SAGA: Standardizing Compute Grid Access in the Open Grid Forum

After seven years of life the Open Grid Forum (OGF), previously the Global Grid Forum, is beginning to produce standards that meet the needs of the community and that are being adopted by commercial and open source software providers. Accessing computational resources, specifically high performance computing resources, is a usage scenario that predates the emergence of the Grid and is well understood within the community. Building on this consensus the HPC Profile Working Group was established within the OGF to standardize access to HPC resources. Its first specification, the HPC Basic Profile 1.0, has been developed and has established interoperability within the community. Alongside the development of this protocol, another group within the OGF, the Simple API Grid Applications (SAGA) Working Group has been defining a programmatic interface relevant to application developers that encompasses access to compute resources. This paper examines the relationship between the “standard� protocol of the HPC Basic Profile and the programmatic interface of SAGA to access compute resources and assesses how well these address the problems faced by the community of users and application developers.

Accessing RDF(S) Data Resources in Service-based Grid Infrastructures

We describe the results of the RDF(S) activity within the OGF DAIS (Database Access and Integration Services) Working Group, whose objective is to develop standard service-based grid access mechanisms for data expressed in RDF and RDF Schema. We are producing two specifications, focused on the provision of SPARQL querying capabilities for accessing RDF data and a set of RDF Schema ontology handling primitives for creating, retrieving, updating, and deleting RDF data. In this paper we present a set of use cases that justify this work and an overview of these specifications, which will enter in editorial process at OGF23. We conclude by outlining the future work that will be made in the context of this standardisation process.

WS-Naming: Location Migration, Replication, and Failure Transparency Support for Web Services

Naming transparencies, i.e., abstracting the name and binding of the entity being used from the endpoints that are actually doing the work, are used in distributed systems to simplify application development by hiding the complexity of the environment. In this paper we demonstrate how to apply traditional distributed systems naming and binding techniques in the Web Services realm. Specifically, we show how the WS-Naming profile on WS-Addressing Endpoint References can be used for identity, transparent failover, replication, and migration. We begin with a discussion of the traditional distributed systems transparencies. We then present four detailed use cases. Next, we provide brief background on both WS-Addressing and WS-Naming. Finally, we show how WS-Naming can be used to provide transparent implementations of our use cases.

Profiles for Conveying the Secure Communication Requirements of Web Services

The lack of a single authority in the Grid environment is perhaps the biggest source of security and interoperability challenges faced by Grid systems designers. A strong commitment to meaningful, interoperable security is crucial for fostering Grid adoption and buy-in. The issues of securityinteroperability are twofold: (a) grids require federation of distinct trust and security domains, and (b) grid participants need to convey and discover their secure communication requirements. This paper presents two new OGF security profiles that address this latter issue.

The Secure Communication Profile 1.0 is a refinement of the WS-SecurityPolicy specification. The goals of this profile are to impose more restrictive conformance requirements on the WS-Security mechanisms described by WS-SecurityPolicy assertions, to facilitate key distribution, and to profile normative “well-known� policy documents that identify commonly-used security mechanisms.

The Secure Addressing Profile 1.0 refines the WS-Addressing specification in order to profile the inclusion of security policy within Endpoint References (EPRs). This approach of conveying security policy within EPRs is well-suited to the Grid paradigms of stateful Web service resources and factory patterns.

A General Encoding Framework for Representing Network Measurement and Topology Data

Scientific applications are evolving rapidly and rely heavily on the network for data movement, communication, control, and result collection. Efforts to construct intelligent software that is aware of network status as well as features related to the logical and physical aspects of the topology will enable scientists the ability to alter these behaviors and enhance overall performance. The status of the network over time is delivered through monitoring software such as perfSONAR which relies on properly formatted and standardized description formats delivered from the deployed infrastructur.

We present a general model used to represent both network measurements collected from performance tools as well as describing the physical and logical characteristics of the underlying network. This system is currently being standardized in the Open Grid Forum to enable other uses within the wider grid and distributed computing community

Interoperation of World-Wide Production e-Science Infrastructures

Many production Grid and e-Science infrastructures have begun to offer services to end-users during the past several years with an increasing number of scientific applications that require access to a wide variety of resources and services in multiple Grids. Therefore, the Grid Interoperation Now (GIN) - Community Group (CG) of the Open Grid Forum (OGF) organizes and manages interoperation efforts among those production Grid infrastructures to reach the goal of a world-wide Grid vision on a technical level in the near future. This contribution highlights fundamental approaches of the group and discusses open standards in the context of production e-Science infrastructures.

Using Clouds to Provide Grids Higher-Levels of Abstraction and Explicit Support for Usage Modes

Grids in their current form of deployment and implementation have not been as successful as hoped in engendering distributed applications. Amongst other reasons, the level of detail that needs to be controlled for the successful development and deployment of applications remains too high. We argue that there is a need for higher levels of abstractions for current Grids. By introducing the relevant terminology, we try to understand Grids and Clouds as systems; we find this leads to a natural role for the concept of Affinity, and argue that this is a missing element in current Grids. Providing these affinities and higher-level abstractions is consistent with the common concepts of Clouds. Thus this paper establishes how Clouds can be viewed as a logical and next higher-level abstraction from Grids.

Please see the Journal website for additional information.

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