GRIDPP3: Tier-2 support: Durham

“网格”是计算机互联的下一个飞跃。互联网和万维网日益成为人们生活中不可或缺的一部分，帮助全世界快速、轻松地共享信息和传输数据。就像我们现在通过全球计算机网络共享文件和事实一样，未来网格将让我们共享其他东西，比如处理能力和存储空间。网格是一个实用的解决方案，用于存储和处理工业界和科学界在未来十年中将产生的大量数据。粒子物理学家正在等待2007年，届时世界上最大的粒子物理实验室——欧洲核子研究中心（CERN）将启用一个新的粒子加速器。大型强子对撞机（LHC）将是迄今为止用于研究基础物理学的最强大的仪器。一旦它完全发挥作用，产生的数据量将是巨大的。所有这些对于一个机构来说都是太多了，所以他们需要共享资源，即使用分布式计算。网格建立在与web相同的Internet基础设施上，但使用不同的工具。中间件就是其中一种工具。在一台独立的计算机中，分配给每个作业的资源是由操作系统（如Windows、Linux、Unix、Mac OS x）管理的。中间件就像网格的操作系统，允许用户访问资源而无需手动搜索。GridPP与其他国际项目合作，为网格开发了中间件。由于GridPP的开源策略，中间件可以由使用它的人发展和改进。分布式计算对科学家来说已经有一段时间了，但一般来说，不同地点的使用必须由每个科学家单独协商。他们需要一个单独的帐户上的每个系统和工作必须提交和结果收集回来的手。当前的分布式计算意味着用户要做很多工作才能得到结果。这就是网格计算思想的来源。中间件允许用户简单地向网格提交作业，而不必知道数据在哪里或作业将在哪里运行。软件可以在有数据的地方运行作业，或者将数据移动到CPU可用的地方。使用网格和中间件，用户所要做的就是提交作业并获取结果。中间件作为网格的看门人和媒人，监视网格，决定向何处发送计算作业，管理用户、数据和存储。它将通过使用数字证书来检查用户的身份。数字证书是安全存储在用户计算机上的文件，它允许网格正确识别用户。证书由证书颁发机构颁发给用户，其中有许多步骤来确保申请人是他们所说的人。中间件自动从用户的数字证书中提取用户的身份，并使用该身份登录用户。打印日期：13/07/2006 12:20:36 PP/E002889/1保存日期：11/07/2006 15:01:49 Je-SRP1PPARC v1.3这意味着用户不必记住登录到Grid的用户名和密码，他们将使用他们的Grid证书自动登录。在这个无缝的识别过程之后，中间件将为作业找到最方便、最有效的运行地点，并组织对相关科学数据的有效访问。它处理对正在使用的不同站点的身份验证，运行作业，跟踪进度，让用户知道工作何时完成并将结果传输回来。

'The Grid' is the next leap in computer interconnectivity. The Internet and the World Wide Web are increasingly an integral part of people's lives, helping the world share information and transfer data quickly and easily. In the same way as we now share files and facts over the global network of computers, in the future the Grid will let us share other things, such as processing power and storage space. The Grid is a practical solution to the problems of storing and processing the large quantities of data that will be produced by industry and the scientific communities over the next decade. Particle physicists are waiting for 2007 when a new particle accelerator opens in the world's largest particle physics laboratory, CERN. The Large Hadron Collider (LHC) will be the most powerful instrument ever built to investigate fundamental physics. Once this is fully functional the amount of data being produced will be massive. All this will be too much for one institution to handle so they need to share resources i.e. to use distributed computing. The Grid is built on the same Internet infrastructure as the web, but uses different tools. Middleware is one of these tools. In a stand alone computer the resources allocated to each job are managed by the operating system e.g. Windows, Linux, Unix, Mac OS X. Middleware is like the operating system of a Grid, allowing users to access resources without searching for them manually. GridPP has developed middleware for the Grid, in collaboration with other international projects. Due to GridPP's open source policy, the middleware can evolve and be improved by the people who use it. Distributed computing has been available to scientists for some time but, in general, the use of different sites has to be negotiated by each scientist individually. They need a separate account on each system and jobs have to be submitted and results collected back by hand. Current distributed computing means the user has a lot of work to do to get their results. This is where the idea of Grid computing comes in. Middleware lets users simply submit jobs to the Grid without having to know where the data is or where the jobs will run. The software can run the job where the data is, or move the data to where there is CPU power available. Using the Grid and middleware, all the user has to do is submit a job and pick up the results. Acting as the gatekeeper and matchmaker for the Grid, middleware monitors the Grid, decides where to send computing jobs, manages users, data and storage. It will check the identity of the user through the use of digital certificates. A digital certificate is a file stored securely on a user's computer which allows the Grid to correctly identify a user. The certificates are given to a user by the Certification Authority, with numerous steps to ensure the person applying is who they say they are. The middleware automatically extracts the users' identity from their digital certificate and uses this to log them in. Section 1.3 Date Printed: 13/07/2006 12:20:36 PP/E002889/1 Date Saved: 11/07/2006 15:01:49 Je-SRP1PPARC v1.3 This means users don't have to remember user names and passwords to log onto the Grid, they're automatically logged on using their Grid certificate. After this seamless identification process the middleware will find the most convenient and efficient places for the job to be run and organise efficient access to the relevant scientific data. It deals with authentication to the different sites being used, runs the jobs, keeps track of progress, lets the user know when the work is complete and transfers the result back.