- The Grid: A new infrastructure for 21st century science. - Now, they want to calcu- late the structures of complex assemblies of macromolecules (see Figure 2.1) and screen thousands of drug candidates. - three orders of magnitude faster than the state-of-the- art 56 kilobits per second (Kb s − 1 ) that connected U.S. - Figure 2.1 Determining the structure of a complex molecule, such as the cholera toxin shown here, is the kind of computationally intense operation that Grids are intended to tackle. - What many term the ‘Grid’ offers a potential means of surmounting these obstacles to progress [1]. - Built on the Internet and the World Wide Web, the Grid is a new class of infrastructure. - By providing scalable, secure, high-performance mechanisms for discover- ing and negotiating access to remote resources, the Grid promises to make it possible for scientific collaborations to share resources on an unprecedented scale and for geographi- cally distributed groups to work together in ways that were previously impossible [2–4].. - In 1965, MIT’s Fernando Corbat´o and the other designers of the Multics operating system envisioned a computer facility operating ‘like a power company or water company’ [5]. - Now, however, a combination of technology trends and research advances makes it feasi- ble to realize the Grid vision – to put in place a new international scientific infrastructure with tools that, together, can meet the challenging demands of twenty-first century science. - (For a list of major Grid projects, see http://www.mcs.anl.gov. - Spurred by such innovations as doping, which boosts the performance of optoelectronic devices, and by the demands of the Internet economy [7], the performance of wide area networks doubles every nine months or so. - The NSFnet network, which connects the National Science Foundation supercomputer centers in the U.S., exemplifies this trend. - This year, the centers will be connected by the 40 Gb s −1 TeraGrid network (http://www.teragrid.org. - To exploit this bandwidth bounty, we must imagine new ways of working that are communication intensive, such as pooling computational resources, streaming large amounts of data from databases or instruments to remote computers, linking sensors with each other and with computers and archives, and connecting people, computing, and storage in collaborative environments that avoid the need for costly travel [8].. - Next, I must negotiate access to them (to be practical, this step cannot involve using the telephone. - And I must do all these things without compromising my own security or the security of the remote resources that I make use of, some of which I may have to pay for.. - Providing the infrastructure and tools that make large-scale, secure resource sharing possible and straightforward is the Grid’s raison d’ˆetre.. - and the Internet allows us to communicate with virtually any electronic device.. - To be useful, an infrastructure technology must be broadly deployed, which means, in turn, that it must be simple, extraordinarily valuable, or both. - And of course, the need remains for supporting the resources that power the Grid, such as high-speed data movement, caching of large datasets, and on-demand access to computing.. - But the Grid goes beyond sharing and distributing data and computing resources. - For the scientist, the Grid offers new and more powerful ways of working, as the following examples illustrate:. - Science portals make advanced problem-solving methods easier to use by invoking sophisticated packages remotely from Web browsers or other simple, easily downloaded ‘thin clients.’ The packages themselves can also run remotely on suitable computers within a Grid. - For a week, the collaboration brought an average of 630 – and a maximum of 1006 – computers to bear on Nug30, delivering a total of 42 000 CPU-days. - For example, the analysis of the many petabytes of data to be produced by the LHC and other future high-energy physics experiments will require the marshalling of tens of thousands of processors and hundreds of terabytes of disk space for holding inter- mediate results. - Yet the collective institutional and national resources of the hundreds of institutions participating in those experiments can provide these resources. - Computer-in-the-loop instrumentation : Scientific instruments such as telescopes, syn- chrotrons, and electron microscopes generate raw data streams that are archived for subsequent batch processing. - For example, an astrophysicist who has performed a large, multiterabyte simulation might want colleagues around the world to visualize the results in the same way and at the same time so that the group can discuss the results in real time.. - Real Grid applications will frequently contain aspects of several of these – and other–scenarios. - Close to a decade of focused R&D and experimentation has produced considerable con- sensus on the requirements and architecture of Grid technology (see Box 2.1 for the early history of the Grid). - Also essential are standard application programming interfaces (APIs), which define standard interfaces to code libraries and facilitate the construction of Grid components by allowing code components to be reused.. - Grid concepts date to the earliest days of computing, but the genesis of much current Grid R&D lies in the pioneering work conducted on early experimental high-speed networks, such as the gigabit test beds that were established in the U.S. - in the early 1990s [9].. - Another test bed, Blanca, connected sites in the Midwest. - Charlie Catlett of the National Center for Supercomputing Applications and his colleagues used Blanca to build multimedia digital libraries and demonstrated the potential of remote visualization. - at least, the event that moved Grid concepts out of the net- work laboratory and into the consciousness of ordinary scientists was the I-WAY experiment [10]. - Led by Tom DeFanti of the University of Illinois at Chicago and Rick Stevens of Argonne National Laboratory, this ambitious effort linked 11 experimental networks to create, for a week in November 1995, a national high- speed network infrastructure that connected resources at 17 sites across the U.S.. - Developed by the author and others, I-Soft provided unified scheduling, single sign-on, and other services that allowed the I-WAY to be treated, in some important respects, as an integrated infrastructure. - As Figure 2.2 shows schematically, protocols and APIs can be categorized according to the role they play in a Grid system. - Diverse resources such as computers, storage media,. - Figure 2.2 Grid architecture can be thought of a series of layers of different widths. - Box 2.2 The Globus Toolkit. - The Globus Toolkit (http://www.globus.org/) is a community-based, open-architecture, open-source set of services and software libraries that supports Grids and Grid appli- cations. - Some of these services and tools are distributed as part of the toolkit, while others are available from other sources. - The NSF-funded GRIDS Center (http://www.grids-center.org/) maintains a repository of components.. - Globus Project and Globus Toolkit are trademarks of the University of Chicago and University of Southern California.. - Because they combine and exploit components from the relatively narrower resource and connectivity layers, the components of the collective layer can implement a wide variety of tasks without requiring new resource-layer components.. - monitoring the progress of the various computations and data transfers, notifying the user when all are completed, and detecting and responding to failure conditions (resource protocols).. - The University of Wisconsin’s Condor-G system (http://www.cs.wisc.edu/condor) is an example of a powerful, full-featured task broker.. - We use the technologies whenever we visit e-Commerce Web sites such as Amazon to buy products on-line.. - Manag- ing that kind of transaction turns out to have a number of interesting requirements, such as. - In Figure 2.3, the program run by the user (the user proxy) uses a proxy credential to authenticate at two different sites. - Mapping to local security mechanisms : Different sites may use different local secu- rity solutions, such as Kerberos and Unix as depicted in Figure 2.3. - In Figure 2.3, processes execute under a local. - (1) Single sign-on via “grid-id”. - Figure 2.3 Smooth and efficient authentication and authorization of requests are essential for Grid operations. - Mediating these requests requires the Grid Security Infrastructure (GSI), which provides a single sign-on, run-anywhere authentication service, with support for delegation of credentials to subcomputations, local control over authorization, and mapping from global to local user identities. - Also required is the Grid Resource Access and Management (GRAM) protocol and service, which provides remote resource allocation and process creation, monitoring, and management services.. - In Figure 2.3, the two subcomputations created at sites A and B both communicate with each other and access files at site C. - Authentication operations – and hence further delegated credentials – are involved at each stage, as resources determine whether to grant requests and computations determine whether resources are trustwor- thy. - These delegation operations and the credentials that enable them must be carefully managed.. - Instead, resources (and users) need to be able to express policies in terms of other criteria, such as group membership, which can be identified with a cryptographic credential issued by a trusted third party. - In the scenario depicted in Figure 2.3, the file server at site C must know explicitly whether the user is allowed to access a particular file. - A community authorization system allows this policy decision to be delegated to a community representative.. - As the Grid matures, standard technologies are emerging for basic Grid operations. - With more than 1000 people on its mailing lists, the Global Grid Forum (http://www.gridforum.org/) is a significant force for setting standards and community development. - In a future in which computing, storage, and software are no longer objects that we possess, but utilities to which we subscribe, the most successful scientific communities are likely to be those that succeed in assembling and making effective use of appropriate. - Box 2.3 Commercial Grids and the Open Grid Services Architecture. - One consequence of this convergence is a growing interest in the integration of Grid technologies with previously distinct commercial technologies, which tend to be based on so-called Web services. - By requiring input, such as a customer’s address, in a certain format, Web services end up setting standards for remote services on the Web. - Several major industrial distributed computing technologies, such as the Microsoft. - Figure 2.4 The International Virtual Data Grid Laboratory (iVDGL) (http://www.ivdgl.org/) is being established to support both Grid research and production computing. - (eds) (1999) The Grid: Blueprint for a New Computing Infras- tructure. - http://www.globus.org/research/papers/anatomy.pdf.. - http://www.nap.edu/books html.. - Proc Available at http://www.multicians.org/fjcc3.html.. - Technol., Also available at http://memex.org/licklider.pdf.. - (2000) A Brief History of the Internet. - Reston, VA: Internet Society, Avail- able at a http://www.isoc.org/internet-history/brief.html.. - (2002) The Physiology of the Grid: An Open Grid Services Architecture for Distributed Systems Integration. - Argonne, IL: Argonne National Laboratory, Available at http://www.globus.org/research/papers/ogsa.pdf.. - (1965) Libraries of the Future
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