Grid RPC meets Data Grid: Network Enabled Services for Data Farming on the Grid

The Computational Grid[1] is a promising platform for running large-scale scientific applications. It provides a base software infrastructure that allows for the development of middleware aimed at deploying applications on Grid resources. The question is, how do you program it---in this regard, Network-Enabled Server (NES) paradigm, which enables Grid-based RPC, or GridRPC for short is a good candidate as a viable Grid middleware that offers a simple yet powerful programming paradigm for programming on the Grid. Several systems that facilitate whole or parts of the paradigm are already in existence, such as Neos[7], Netsolve[3], Nimrod/G[4], Ninf[2], and RCS[6], and we feel that pursuit of a common design in GridRPC, as had been done for MPI for message passing, will bring benefits of standardized programming model to the Grid world. This talk will introduce the NES/Grid RPC features, discuss early user experiences, and touch upon the Grid Data Farm project, based on Grid RPC, which involving processing Petabytes of collider accelerator data streaming over the Euro-Japanese link with thousands-node scale cluster possibly spread over several Japanese institutions. Compared to traditional RPC systems, such as CORBA, designed for applications that facilitate nonscientific applications, GridRPC systems offer features and capabilities that make it easy to program mediumto coarse-grained, task parallel applications that involve hundreds to thousands or more high-performance nodes, either concentrated as a tightly coupled cluster, or a set of them spread over a wide-area network. Such applications will often require handling of shipping megabytes of multidimensional array data in a user-transparent and efficient way, as well as requiring the support of RPC calls that range anywhere from 100s of milliseconds up to several days or even weeks. There are other necessary features of Grid RPC systems such as dynamic resource discovery, dynamic load balancing, fault tolerance, security (multisite authentication, delegation of authentication, adapting to multiple security policies, etc.), easy-to-use client/server management, firewall and private address considerations, remote large file and I/O support etc. These features are essentially what is needed for the Grid RPC systems to execute well on the Grid---features either missing or incomplete in traditional `closed world’ RPC systems ---and in fact are what are provided by lower level Grid substrates such as Condor[10], Globus[8], and Legion[9]. As such GridRPC systems either provide these features themselves, or builds upon the features provided by such substrates.