A layered Virtual Organization architecture for grid

Virtual Organizations (VOs) are dynamic collections of individuals, institutions, and resources. VOs are widely accepted in grid and other distributed computing environments. Previous VO research produces several separate tools to provide part of the functionality including user registration, user mapping, authentication, authorization, and VO management. However, none of the work covers all the functionality or focuses on non-functional properties. This paper formally defines virtual organization in terms of three functional requirements and four non-functional properties. The functional requirements are user management, resource management, and VO management. The non-functional properties are decentralization, flexibility, simplicity, and efficiency. The problem is formulated as designing a VO architecture to satisfy the functional requirements and achieve the non-functional properties at the same time. This paper presents a layered architecture with GNode abstraction to construct Agora, an implementation of VOs. In Agora architecture, all the entities including users, resources, and agoras are abstracted as GNodes. A naming layer is constructed to manage these GNodes. At the top, there is a logic layer implementing all Agora functionality based on GNode and managing the physical layer resources. The Agora architecture has been implemented in the Vega Grid Operating System. Agora is deployed in the China National Grid and other grid platforms with more than 27 sites and 19 applications. The evaluations through real applications, high performance computing VO scenarios, and micro benchmarks show that the Agora architecture provides complete VO functionality, while achieving decentralization, flexibility, simplicity, and efficiency.