DEISA: E-Science in a collaborative, secure, interoperable and user-friendly environment

The paper presents actual results and current research of the DEISA project, with a focus on major contributions to the field of e-Infrastructures, collaborative working environments, security and identity management, interoperability and standardisation, and high performance computing applications. Aim is to focus on research areas and results so far not published in such detail elsewhere. In addition, we describe three examples of high performance computing applications which strongly benefitted from running on the DEISA infrastructure, as represented by the DEISA Extreme Computing Initiative (DECI) or more recently, by so-called virtual communities and their scientific endeavours.