Workflow Support for Complex Grid Applications: Integrated and Portal Solutions 1 R. Lovas, G. Dózsa, P. Kacsuk, N. Podhorszki, D. Drótos MTA SZTAKI Laboratory of Parallel and Distributed Systems, H-1518 Budapest P.O.Box 63, Hungary {rlovas | dozsa | kacsuk | pnorbert | drotos}@sztaki.hu Abstract. In this paper we present a workflow solution to support graphically the design, execution, monitoring, and performance visualisation of complex grid applications. The described workflow concept can provide interoperability among different types of legacy applications on heterogeneous computational platforms, such as Condor or Globus based grids. The major design and implementation issues concerning the integration of Condor/Condor- G/DAGman tools, Mercury/GRM grid monitoring infrastructure, PROVE performance visualisation tool, and the new high-level workflow editor and manager of P-GRADE development environment are discussed in the case of the integrated and the portal version as well. The integrated version of P- GRADE represents the thick client concept, while the portal version needs only a thin client and can be accessed by a standard web browser. To illustrate the application of our approach in the grid, an ultra-short range weather prediction system is presented that can be executed on a Condor-G/Globus based testbed and its execution can also be visualised not only at workflow level but at the level of individual jobs, too. 1 Introduction The workflow concept is a widely accepted approach to compose large scale applications by connecting programs into an interoperating set of jobs in the Grid [6][12][17][19][20]. Our main aim was to develop a workflow solution for complex grid applications to support the design, execution, monitoring, and performance visualisation phases of development in a user-friendly way. In the presented approach the interoperability among different types of legacy applications executed on heterogeneous platforms, such as Condor or Globus based computational grids, is the particularly addressed issue beside the efficient monitoring and visualisation facilities in the grid. Several achievements of different grid-related projects have been exploited in the presented work to hide the low-level details of heterogeneous software components as well as to provide a unified view for application developers. These targets are crucial 1 The work presented in this paper was partially supported by the following grants: EU- GridLab IST-2001-32133, Hungarian SuperGrid (IKTA4-075), IHM 4671/1/2003, and Hungarian Scientific Research Fund (OTKA) No. T042459 projects.