Grid technologies enable large-scale sharing of resources within formal or informal consortia of individuals and/or institutions: what are sometimes called virtual organizations. In these settings, the discovery, characterization, and monitoring of resources, services, and computations are challenging problems due to the considerable diversity, large numbers, dynamic behavior, and geographical distribution of the entities in which a user might be interested. Consequently, information services are a vital part of any Grid software infrastructure, providing fundamental mechanisms for discovery and monitoring, and hence for planning and adapting application behavior. We present here an information services architecture that addresses performance, security, scalability, and robustness requirements. Our architecture defines simple low-level enquiry and registration protocols that make it easy to incorporate individual entities into various information structures, such as aggregate directories that support a variety of different query languages and discovery strategies. These protocols can also be combined with other Grid protocols to construct additional higher-level services and capabilities such as brokering, monitoring, fault detection, and troubleshooting. Our architecture has been implemented as MDS-2, which forms part of the Globus Grid toolkit and has been widely deployed and applied.

In an increasing number of scientific disciplines, large data collections are emerging as important community resources. In this paper, we introduce design principles for a data management architecture called the Data Grid. We describe two basic services that we believe are fundamental to the design of a data grid, namely, storage systems and metadata management. Next, we explain how these services can be used to develop higher-level services for replica management and replica selection. We conclude by describing our initial implementation of data grid functionality.

Clusters, grids, and peer-to-peer (P2P) networks have emerged as popular paradigms for next generation parallel and distributed computing. They enable aggregation of distributed resources for solving large-scale problems in science, engineering, and commerce. In grid and P2P computing environments, the resources are usually geographically distributed in multiple administrative domains, managed and owned by different organizations with different policies, and interconnected by wide-area networks or the Internet.

The realization of end-to-end quality of service (QoS) guarantees in emerging network-based applications requires mechanisms that support first dynamic discovery and then advance or immediate reservation of resources that will often be heterogeneous in type and implementation and independently controlled and administered.We propose the Globus Architecture for Reservation and Allocation (GARA) to address these four issues.GARA treats both reservations and computational elements such as processes, network flows, and memory blocks as first class entities, allowing them to be created, monitored, and managed independently and uniformly.It simplifies management of heterogeneous resource types by defining uniform mechanisms for computers, networks, disk, memory, and other resources. Layering on these standard mechanisms, GARA enables the construction of application-level co-reservation and coallocation libraries that applications can use to dynamically assemble collections of resources, guided by both application QoS requirements and the local administration policy of individual resources.We describe a prototype GARA implementation that supports three different resource types— parallel computers, individual CPUs under control of the Dynamic Soft Real-Time scheduler, and Integrated Services networks—and provide performance results that quantify the costs of our techniques.

In wide area computing, programs frequently execute at sites that are distant from their data. Data access mechanisms are required that place limited functionality demands on an application or host system yet permit high-performance implementations. To address these requirements, we propose a data movement and access service called Global Access to Secondary Storage (GASS). This service defines a global name space via Uniform Resource Locators and allows applications to access remote files via standard I/O interfaces. High performance is achieved by incorporating default data movement strategies that are specialized for I/O patterns common in wide area applications and by providing support for programmer management of data movement. GASS forms part of the Globus toolkit, a set of services for high-performance distributed computing. GASS itself makes use of Globus services for security and communication, and other Globus components use GASS services for executable staging and real-time remote monitoring. Application experiences demonstrate that the library has practical utility.

A fundamental problem with distributed applications is how to map activities such as computation or data transfer onto a set of resources that will meet the application’s requirement for performance, cost, security, or other quality of service metrics. An application or client must engage in a multi-phase negotiation process with resource managers, as it discovers, reserves, acquires, configures, monitors, and potentially renegotiates resource access. We present a generalized resource management model in which resource interactions are mapped onto a well defined set of symmetric and resource independent service level agreements. We instantiate this model in (the Service Negotiation and Acquisition Protocol (SNAP) which provides integrated support for lifetime management and an at-most-once creation semantics for SLAs. The result is a resource management framework for distributed systems that we believe is more powerful and general than current approaches. We explain how SNAP can be deployed within the context of the Globus Toolkit. 1

Application development for high-performance distributed computing systems, or computational grids as they are sometimes called, requires "grid-enabled" tools that hide mundane aspects of the heterogeneous grid environment without compromising performance. As part of an investigation of these issues, we have developed MPICH-G, a grid-enabled implementation of the Message Passing Interface (MPI) that allows a user to run MPI programs across multiple computers at different sites using the same commands that would be usedonaparallel computer. This library extends the Argonne MPICH implementation of MPI to use services provided by the Globus grid toolkit. In this paper, we describe the MPICH-G implementation and present preliminary performance results.

Grid Portals, based on standard Web technologies, are increasingly used to provide user interfaces for Computational and Data Grids. However, such Grid Portals do not integrate cleanly with existing Grid security systems such as the Grid Security Infrastructure (GSI), due to lack of delegation capabilities in Web security mechanisms. We solve this problem using an online credentials repository system, called MyProxy. MyProxy allows Grid Portals to use the GSI to interact with Grid resources in a standard, secure manner. We examine the requirements of Grid Portals, give an overview of the GSI, and demonstrate how MyProxy enables them to function together. The architecture and security of the MyProxy system are described in detail. 1

With the advent of Grid and application technologies, scientists and engineers are building more and more complex applications to manage and process large data sets, and execute scientific experiments on distributed resources. Such application scenarios require means for composing and executing complex workflows. Therefore, many efforts have been made towards the development of workflow management systems for Grid computing. In this paper, we propose a taxonomy that characterizes and classifies various approaches for building and executing workflows on Grids. We also survey several representative Grid workflow systems developed by various projects world-wide to demonstrate the comprehensiveness of the taxonomy. The taxonomy not only highlights the design and engineering similarities and differences of state-of-the-art in Grid workflow systems, but also identifies the areas that need further research.

The emerging paradigm of electronic services promises to bring to distributed computation and services the flexibility that the web has brought to the sharing of documents. An understanding of fundamental properties of e-service composition is required in order to take full advantage of the paradigm. This paper examines proposals and standards for e-services from the perspectives of XML, data management, workflow, and process models. Key areas for study are identified, including behavioral service signatures, verification and synthesis techniques for composite services, analysis of service data manipulation commands, and XML analysis applied to service specifications. We give a sample of the relevant results and techniques in each of these areas.