  We propose a formal framework that supports a model of agent-based Virtual
Organisations (VOs) for service grids and provides an associated operational
model for the creation of VOs. The framework is intended to be used for
describing different service grid applications based on multiple agents and, as
a result, it abstracts away from any realisation choices of the service grid
application, the agents involved to support the applications and their
interactions. Within the proposed framework VOs are seen as emerging from
societies of agents, where agents are abstractly characterised by goals and
roles they can play within VOs. In turn, VOs are abstractly characterised by
the agents participating in them with specific roles, as well as the workflow
of services and corresponding contracts suitable for achieving the goals of the
participating agents. We illustrate the proposed framework with an earth
observation scenario.
