Globus Ian Foster and Carl Kesselman Argonne National Laboratory and University of Southern California

Computational Grid The Definition A distributed computing infrastructure for coordinated resource sharing and problem solving in dynamic multi- institutional virtual organizations

Computational Grid Examples Financial forecasting with ASP and SSP Industry consortium for feasibility study using multidisciplinary simulation Crisis management responding to oil spill Multi-institutional high-energy physics collaboration for analyzing petabytes of data

Computational Grid Characteristics Heterogeneous and dynamic environment Diverse and dynamic resource-sharing relationships across multiple administrative domains Performance critical

Computational Grid A New Challenge? Differs from traditional distributed systems Resource sharing vs. Information sharing Peer-to-peer vs. Client/Server Computation vs. Communication Differs from traditional parallel computing Loosely coupled, heterogeneous, and dynamic systems Spans over multiple administrative domains

Design Issues Interoperability vs. Flexibility Performance vs. Convenience Local control vs. Global coordination

Design Philosophies A bag of services The hourglass principle: a balance between interoperability and flexibility Translucency: a balance between performance and convenience Layered design: Enabling global coordination while maintaining local control

Design Philosophies The Hourglass Principle

Design Philosophies Translucency Managing heterogeneity, not simply hiding it Transparency for convenience Exposing certain low-level details to facilitate performance optimization

Design Philosophies Translucency: Examples Provide ways to discover and control aspects of the underlying system Reliability or Low latency Security or No security Message passing, Shared memory, or IP SPEP

Design Philosophies Layered Design

Design Philosophies Layered Design: Layers Fabric: Interfaces to local control Connectivity: Communicating easily and securely Resource: Sharing local resources Collective: Coordinating multiple resources Applications

Design Philosophies Layered Design: Examples

Globus Layers

Conclusion Computational grid poses challenges that are beyond the current state of art in distributed systems and parallel computing Globus provides an infrastructure to addressing these issues with interesting design philosophies