Advanced Resource Connector (ARC) – The Grid Middleware of the NorduGrid

Abstract

The Advanced Resource Connector (ARC), or the NorduGrid middleware, is an open source software solution enabling production quality computational and data Grids. Since the first release (May 2002) the middleware is deployed and being used in production environments. Emphasis is put on scalability, stability, reliability and performance of the middleware. A growing number of grid deployments chose ARC as their middleware, thus building one of the largest production Grids of the world.

The NorduGrid middleware integrates computing resources (commodity computing clusters managed by a batch system or standalone workstations) and Storage Elements, making them available via a secure common grid layer. ARC provides a reliable implementation of the fundamental grid services, such as information services, resource discovery and monitoring, job submission and management, brokering and data management.

The middleware builds upon standard open source solutions like OpenLDAP, OpenSSL, SASL and Globus Toolkit 2 (GT2) libraries. NorduGrid provides innovative solutions essential for a production quality middleware: Grid Manager, ARC GridFTP server, information model and providers (NorduGrid schema), User Interface and broker (a “personal” broker integrated into the user interface), extended Resource Specification Language (xRSL), and the monitoring system.

ARC solutions are replacements and extensions of the original GT2 services, the middleware does not use most of the core GT2 services, such as the GRAM, the GT2 job submission commands, the WUftp-based gridftp server, the gatekeeper, the job-manager, the GT2 information providers and schemas. Moreover, ARC extended the RSL and made the Globus MDS functional. ARC is thus much more than GT2 – it offers its own set of Grid services built upon the GT2 libraries.