Grid computing offers a model for solving massive computational problems using large numbers of computers arranged as clusters embedded in a distributed telecommunications infrastructure. Grid computing's focus on the ability to support computation across administrative domains sets it apart from traditional distributed computing.
Grid computing has the design goal of solving problems too big for any single supercomputer, whilst retaining the flexibility to work on multiple smaller problems. Thus grid computing provides a multi-user environment.
This implies the use of secure authorization techniques to allow remote users to control computing resources.
Grid computing involves sharing heterogenous resources (based on different platforms, hardware/software architectures, and computer languages), located in different places belonging to different administrative domains over a network using open standards. In short, it involves virtualizing computing resources.
Functionally, one can classify grids as:
Computational Grids (including CPU scavenging grids), or as:
Data Grids.
The Global Grid Forum (GGF) has the purpose of defining specifications for grid computing. The Globus Toolkit implements its standards, and has become the de facto standard for grid middleware. As a middleware component, it provides a standard platform for services to build upon, but grid computing needs other components as well, and many other tools operate to support a successful Grid environment. This situation resembles that of TCP/IP: the usefulness of the Internet emerged both from the success of TCP/IP and the establishment of applications such as newsgroups and webpages.
Globus has implementations of the GGF-defined protocols to provide:
Resource management: Grid Resource Allocation & Management Protocol (GRAM)
Information Services: Monitoring and Discovery Service (MDS)
Security Services: Grid Security Infrastructure (GSI)
Data Movement and Management: Global Access to Secondary Storage (GASS) and GridFTP
A number of tools function along with Globus to make grid computing a more robust platform, useful to high-performance computing communities. They include:
- Grid Portal Software such as GridPort and OGCE
- Grid Packaging Toolkit (GPT)
- MPICH-G2 (Grid Enabled MPI)
Network Weather Service (NWS) (Quality-of-Service monitoring and statistics) - Condor (CPU Cycle Scavenging) and Condor-G (Job Submission)
- Most of the grids which span research and academic communities in North America and Europe utilise the Globus Toolkit as their core middleware.
XML-based web services offer a way for accessing diverse services/applications in a distributed environment. As of 2003 the worlds of grid computing and of web services have started to converge to offer Grid as a web service (Grid Service). The Open Grid Services Architecture (OGSA) has defined this environment, which will offer several functionalities adhering to the semantics of the Grid Service.
Grids offer a way to solve Grand Challenge problems like protein folding, drug discovery, financial modelling, earthquake simulation, climate/weather modelling etc. Grids offer a way of using the information technology resources optimally in an organisation. They also provide a means for offering information technology as a utility bureau for commercial and non-commercial clients, with those clients paying only for what they use, as with electricity or water.
