The WIEN2k application-plugin for W2GRID

Complex scientific applications need vast computational resources and are therefore increasingly used in a distributed computing environment. Popular grid-projects often have unfavourable requirements such as root-permission and they require essential changes to the application leading to solutions, which strongly depend on the architecture and thus are poorly portable. Therefore we developed W2GRID, a lightweight remote-procedure-call based perl infrastructure, which ’attaches’ grid-capabilities to otherwise unchanged programs. This approach is more likely to be accepted by users and developers than embedding middleware function-calls and the associated libraries directly into the source-code. The ’plugin-technology’ used by W2GRID supports a high portability with respect to the architecture (namely operating-system and job-submission) and allows to treat computing resources in a highly abstract way. The applications are ’wrapped’ by dedicated interface scripts, the so called ’application-plugins’. Since the original code remains unchanged, it can also be run without W2GRID. In this paper we explain how this approach works for WIEN2k, which is a software program for material science calculations, already licensed to more than thousand groups worldwide.