外文翻译---超越台式机：一个关于云计算的介绍

1、.附录A 译文超越台式机：一个关于云计算的介绍 在这个世界上几乎每一天都能看到新技术趋势的崛起和衰退，一种新的趋势带来了更长久的生命力。这种趋势被称为云计算，它将改变你使用电脑和互联网的方式。云计算预示着我们在如何存储信息和运行应用程序问题上的重大变革。而不是在单独的计算机上运行程序的散的数据，一切都托管在“云”中，通过英特网去访问“云”中的其他计算机和服务器。云计算让你能够在世界上的任何地方访问你所有的应用程序和文档，摆脱了台式机的束缚，让你更容易在不同的地方和同事进行协作。第一部分 认识云计算云计算的出现就相当于一个世纪前电力革命的发生。在电力公司出现之前，每一个农场和企业都通过自己独立的

2、发电机发电。在电网产生以后，农场和企业关闭他们自己的的发电机，并且从电力公司以一个比他们用自己发电机发电低得多的价格（并且更具有可靠性）买电。为了寻找相同类型革命的发生，使得云计算成为定局。由于我们所期望的教育普及，每时每刻的可靠性和无处不在的云计算协作承诺使得以台式机为计算中心的观念半途而废。云计算将是未来发展的方向。云计算：它是什么和它的不同通过传统的桌面计算，你可以在你的每一台电脑上运行程序的副本，你所创建的文件都保存在你创建文件的计算机上。虽然它们能够被这个网络上的其他计算机访问，但是它们不能被外网的计算机访问。整个的场景都是以个人计算机为中心。通过云计算，你使用的软件程序不需要运行在

3、你的个人电脑上，但是却可以通过访问英特网上的服务器使用这个软件程序。假如你的电脑死机了，但是这个软件程序仍然可以供其他人使用。这种模式仍然适用于你创建的文件，它们被储存在一个可以通过互联网访问的集合中。经过许可的任何人不仅可以访问文件，还可以实时地编辑和处理这些文件。不同于传统的计算，云计算模式不以个人计算机为中心，而是以文档为中心，个人计算机使用简单的文件访问并不重要。但是这只是一个简化。让我们来看看更详细的云计算是什么样子的？它和我们了解云计算的不同同样重要。云计算的不同首先，云计算不是网络计算。通过网络计算，应用程序和文档被托管在一个公司的服务器中并且通过公司的网络可以访问那些应用程序和

4、文档。云计算要比网络计算大很多，它包含了许多个公司，许多个服务器和许多个网络。此外，与网络计算不同，云服务和储存通过网络在世界的任何地方都可以访问，但是通过网络计算，只能在自己公司的网络访问到。云计算也不是传统的像一个公司将计算服务外包（分包）给一个外部公司。虽然外包公司可以托管一个公司的数据或者应用程序，但是这些程序和计划只有这个公司的员工通过公司的网络才能访问到，而不是通过整个英特网。因此，尽管表面上很相似，但是网络计算和外包不是云计算。什么是云计算云计算定义的关键是“云”本身。对于我们而言，云是一大群互联的计算机。这些计算机可以是个人电脑或者网络服务器，它们可以是公共或者私人的。例如，谷

5、歌的云是由小的个人电脑和更大的服务器组成的。谷歌云是私人的（即，谷歌拥有它），是公开访问的（通过谷歌用户）。这种计算机云继承并且超越了单一的公司或者企业。跨企业的跨平台的广大用户群可以访问云服务所提供的应用程序和数据。通过互联网访问，任何被授权的用户可以访问连接在英特网上的任何计算机上的这些文档和应用程序。并且，对于用户而言，云技术和云背后的基础设施是不可见的。云技术是否基于HTTP,HTML协议，XML，JavaScript或者其他特定的技术是不明显的。（在大多数情况下是无所谓的）。云计算是用户为中心的。一旦你作为一个用户连接到云，无论储存在哪里的文件，信息，图像，应用程序，无论什么都将变成

6、你的。此外，你的数据也可以和他人分享。事实上，任何访问你的数据的设备在云中都将变成你的。云计算是以任务为中心的。而不是以应用程序和它能为你做什么为重点，重点是你需要做什么和应用程序怎样为你完成这个需求。传统的应用程序-文字处理，电子表格，电子邮件等，都将变得没有它们所产生的文件重要。第二部分 认识云计算云计算是强大的。连接在一起的数百台或者数千台计算机共同创造的计算能力是一台单独的台式计算机无法比拟的。云计算是可访问的。因为数据被存储在云中，用户可以迅速地从多个库中检索出更多的信息，你不仅限于一个单独的数据源，如同你和你的台式个人电脑一样。云计算是智能的。由于云中电脑储存着各种数据，数据挖掘和

7、分析对于以智能的方式访问这些信息是必要的。云计算是可编程的。许多伴随云计算的必要任务必须要实现自动化。例如，要保护存储在云中某台计算机上的集成数据和信息需要在云中的另外一台计算机上完整的复制。如果云中的某台准备被用于复制这些数据和信息的计算机脱机，那么云的编程将自动的将该计算机的数据复制到云中新的计算机上。所有的这些都是在我们背后定义的，那么什么才是现实世界中的云计算？当你学习完整本书，网站托管，互联网访问，团体协作的应用程序一般是可用的。伴随着更多的方式，也许今天最好最流行的云计算应用例子就是谷歌大家庭中的应用程序-谷歌文档和电子表格，谷歌日历，谷歌邮箱，图片管理等等。这些应用都被托管在谷歌

8、的服务器中，是任何连接在互联网上的用户都可以访问的，可用于在世界不同地域的团体协作。总之，云计算使计算机转移到用户，从应用到任务，从孤立的数据到任何地方都可以访问到的数据，并且与任何人共享。用户不再承担管理数据的任务，他甚至不需要记得数据在哪里。所有的事实是数据在云中，对于用户和被授权的用户是可以迅速访问的。从协作到云：云计算的简史云计算的前身是客户机/服务器模式的计算和点对点的分布式计算。问题是如何集中存储协作和如何使多台计算机协同工作以增加计算能力。客户机/服务器模式计算：集中应用和存储很久以前的计算（1980年左右）,一切的操作都是客户机/服务器模式。所有的应用程序，所有的数据，都被放在

9、大型计算机上，这种大型计算机被称为服务器。如果用户想访问特定的数据或者运行程序，就必要连接到大型计算机，获得适当的访问，然后从大型计算机上得到程序或者数据以完成相应的操作。用户通过计算机终端连接到服务器，有时也被称为工作站或者客户端。这台计算机有时被称为哑终端，因为它没有足够（如果有的话）的内存，存储空间，处理能力。这仅仅是连接到一个用户，使他能够使用计算机主机设备。当用户获准访问大型主机时，信息技术(IT)的工作人员没有偶然访问时不在的习惯。甚至在一个大型主机上，处理能力也是有限的-IT工作人员有监护这种处理能力的权利。这种访问不是立竿见影的，也不可能有两个用户同时访问相同的数据。除此之外，

10、用户几乎不得不采取IT工作人员给他们的一切措施（没有任何变化）。想要使用自定义报告去显示正常的信息子集？但是你不能这么做，虽然IT工作人员可以，但是这是他们从现在开始到数周后的日程安排。事实是，当许多人共用一台计算机，即使这是一台大型主机，你也不得不排队等候。需要返回一个财务报告？没问题，如果你不介意一直等到今天下午或者明天早上。在客户机/服务器模式环境中总是没有直接访问的，很少满足直接访问的情况。因此客户机/服务器模式，虽然提供类似的集中存储，但是不同于以用户为中心的云计算，在客户机/服务器模式计算中，所有的控制权在大型主机和控制该台计算机上的人手中。这不是一个有利于用户的环境。点对点计算：

11、资源共享你可以想象，当问客户机/服务器模式的系统是一种“赶快和等待”的经历。该系统的服务器部分还创建了庞大的阻碍。计算机之间的所有通信必须先通过服务器，可是这种方式可能效率太低。 最明显的是由于一台计算机连接到另一台计算机需要通过服务器促使了点对点（P2P）计算的发展。P2P计算定义了网络中每一台计算机具有同等责任和能力的网络架构。这种相对于传统的客户机/服务器模式的网络体系架构，在网络中有一台或者多台计算机是专门为其他计算提供服务的。（这种关系有时有主/从关系的特点，中央服务器是主，客户机是从）。P2P是一个均衡的概念。在P2P环境中，每台计算机是一个客户机和服务器，没有主和从。通过承认所有

12、计算机在网络中的相同地位，P2P使得网络中的计算机可以直接交换资源和提供相互服务。没有中央处理器的需求，因为每一台计算机都能在要求这样做时提供这样的功能。点对点也是分散的概念。控制是分散的，所有计算机的功能是平等的。内容在不同计算机之间也是分散的。没有集中服务器被分配到主机的可用资源和服务。也许最引人注目的P2P计算实施是英特网。今天的许多用户都忘记（也许不知道），英特网最初的设想是在其最初ARPA网的幌子下，作为一个能够分享在美国的计算资源的点对点系统。ARPA网的各种网站（其中的许多不属于他们），连接在一起的计算机不是作为服务器和客户机，而是平等的。初期的P2P英特网最好例子是Usenet

13、网络。它创建于1979年，是一个计算机网络（通过英特网访问）,每一台计算机提供该网络的全部内容。消息在平等的计算机之间传播。用户连接到Usenet的每一个服务器获得所有（或者几乎所有）的消息以张贴到每个单独的服务器。虽然用户连接到Usenet服务器是传统客户机/服务器模式的性质，但是这种Usenet服务器之间的关系肯定了P2P，也预示着今天的云计算。不过，并不是所有的英特网的一部分就是P2P性质。随着万维网中P2P的发展，退后了客户机/服务器模式。在网络上，每一个网站是由一个计算机组提供服务，网站的访问者使用客户端软件（网络浏览器）来访问它。几乎所有的内容都被集中，所有的控制都被集中，在这个过

14、程中，客户端没有自主权或者控制权在。分布式计算：提供更强的计算能力P2P模型中最重要的子集之一是分布式计算，通过个人计算机在网络或者在英特网上的闲置来提供大型的，处理器密集型项目的计算能力。所有关于多台计算机间的周期的共享是一个简单的概念。个人计算机，每天运行满24小时，每周7天，是巨大的计算能力。大多数人不每时每刻使用他们电脑，却除去这样一个电脑的闲置资源。分布式计算使用这些资源。当一台计算机中加入到一个分布式的计算项目，软件被安装在这台计算机上在用户未使用的这段时间去运行各种处理活动。这个业余处理的结果被定期上传到分布式计算网络上，并与项目中其他计算机类似的结果相结合。结果是，如果有足够的

15、计算机被涉及，就模拟了更大的大型主机和超级计算机的处理能力，这对于某些大型和复杂的计算项目的必要的。例如，基因研究需要大量的计算能力。对于传统手段，它可能需要数年的时间来解决基本的数学问题。通过连接在一起的数千（或者百万）台个人计算机，更多的能力适用于这个问题，得出结论就更快。分布式计算的历史可以追溯到1973年，多台计算机联网的施乐公司帕洛阿尔托研究中心是通过网络寻找闲置资源来开发杀毒软件的。一个分布式计算更实际的应用出现在1988年，当DEC（数字设备公司）系统研究中心的研究人员开发软件，在实验室中分布式的工作应用在各个工作组之间以实现大数字。到1990年，大约100个用户组，利用这个软件

16、实现100位数字，到1995年，同样的效果被扩展到网络来实现130位数字。没过多久分布式计算进入了互联网。第一个主要的基于英特网的的分布式计算项目是，在1997年推出，雇佣了成千上万的个人计算机来破译加密代码。即使是较大的SETIhome，1999年5月，推出了使用连接在一起的数百万台的个人计算机搜索外层空间智慧生命。许多分布式计算项目是在大型企业内进行，采用传统的网络连接，形成分布式计算网络。另外，更大的项目通常使用互联网用户的计算机，通常发生脱机，然后每天通过传统的消费英特网上传资料。了解云架构云计算的关键是“云”，一些大规模网络服务器或者个人计算机连接在庞大的网络中。这些计算机并行运行，

17、结合各自的资源，产生超级计算般的能力。究竟什么是“云”？简而言之，云是计算机和服务器都通过英特网公开访问的集合。这种硬件通常是复合的和由有一个或者多个数据中心为稳固基础的第三方运作。这些机器可以运行任何操作系统，这些机器的处理能力不是它们作为单独台式机所能比拟的。如图1.1所示，个人用户使用他们自己的计算机或者便携设备通过英特网连接到云。对于这些个人用户，云被看作是一个单一的应用程序，设备或者文件。云中的硬件（操作系统管理硬件连接）是无形的。这看似简单的云架构，它确实需要一些智能化的管理去将这些计算机连接在一起，并分配任务处理以满足众多的用户。正如你可以看到在图1.2中，这一切都开始于个别用户

18、看到前端界面，选择一个任务或者服务（无论是启动应用程序或者打开一个文档），用户的这些请求被传递到管理系统，然后找出正确的资源，然后调用系统的恰当资源去供应服务。这些服务在云中开拓中必要的资源，发布恰当的网页应用程序，或者创建文件和打开请求的文件，网页应用程序启动后，系统的检测和计量功能跟踪云的使用，使资源分配和使用于正确的用户。正如你所看到的，云计算概念的观念是许多管理任务的自动化。如果一个系统需要人管理资源的分配过程那么这个系统不是云。在这种情况下，该系统是仅仅以老式数据中心为基础的客户机/服务器模式计算的21世纪的版本。对于系统实现云的状态，必须更换人工管理实现自动化程序。附录B 外文原文

19、Beyond the Desktop: An Introduction to Cloud ComputingIn a world that sees new technological trends bloom and fade on almost a daily basis, one new trend promises more longevity. This trend is called cloud computing, and it will change the way you use your computer and the Internet.Cloud computing p

20、ortends a major change in how we store information and run applications. Instead of running program sand data on an individual desktop computer, everything is hosted in the “cloud”a nebulous assemblage of computers and servers accessed via the Internet. Cloud computing lets you access all your appli

21、cations and documents from anywhere in the world, freeing you from the confines of the desktop and making it easier for group members in different locations to collaborate.PART 1 Understanding Cloud Computing The emergence of cloud computing is the computing equivalent of the electricity revolution

22、of a century ago. Before the advent of electrical utilities, every farm and business produced its own electricity from freestanding generators. After the electrical grid was created, farms and businesses shut down their generators and bought electricity from the utilities, at a much lower price (and

23、 with much greater reliability) than they could produce on their own. Look for the same type of revolution to occur as cloud computing takes hold. The desktop-centric notion of computing that we hold today is bound to fall by the wayside as we come to expect the universal access, 24/7 reliability, a

24、nd ubiquitous collaboration promised by cloud computing. It is the way of the future.Cloud Computing: What It Isand What It IsntWith traditional desktop computing, you run copies of software programs on each computer you own. The documents you create are stored on the computer on which they were cre

25、ated. Although documents can be accessed from other computers on the network, they cant be accessed by computers outside the network.The whole scene is PC-centric.With cloud computing, the software programs you use arent run from your personal computer, but are rather stored on servers accessed via

26、the Internet. If your computer crashes, the software is still available for others to use. Same goes for the documents you create; theyre stored on a collection of servers accessed via the Internet. Anyone with permission can not only access the documents, but can also edit and collaborate on those

27、documents in real time. Unlike traditional computing, this cloud computing model isnt PC-centric, its document-centric. Which PC you use to access a document simplyisnt important.But thats a simplification. Lets look in more detail at what cloud computingisand, just as important, what it isnt.What C

28、loud Computing IsntFirst, cloud computing isnt network computing. With network computing, applications/documents are hosted on a single companys server and accessed over the companys network. Cloud computing is a lot bigger than that. It encompasses multiple companies, multiple servers, and multiple

29、 networks. Plus, unlike network computing, cloud services and storage are accessible from anywhere in the world over an Internet connection; with network computing, access is over the companys network only.Cloud computing also isnt traditional outsourcing, where a company farms out (subcontracts) it

30、s computing services to an outside firm. While an outsourcing firm might host a companys data or applications, those documents and programs are only accessible to the companys employees via the companys network, not to the entire world via the Internet.So, despite superficial similarities, networkin

31、g computing and outsourcing are not cloud computing.What Cloud Computing IsKey to the definition of cloud computing is the “cloud” itself. For our purposes, the cloud is a large group of interconnected computers. These computers can be personal computers or network servers; they can be public or pri

32、vate.For example, Google hosts a cloud that consists of both smallish PCs and larger servers. Googles cloud is a private one (that is, Google owns it) that is publicly accessible (by Googles users).This cloud of computers extends beyond a single company or enterprise. The applications and data serve

33、d by the cloud are available to broad group of users, cross-enterprise and cross-platform. Access is via the Internet. Any authorized user can access these docs and apps from any computer over any Internet connection. And, to the user, the technology and infrastructure behind the cloud is invisible.

34、It isnt apparent (and, in most cases doesnt matter) whether cloud services are based on HTTP, HTML, XML, JavaScript, or other specific technologies._ Cloud computing is user-centric. Once you as a user are connected to the cloud, whatever is stored theredocuments, messages, images, applications, wha

35、teverbecomes yours. In addition, not only is the data yours, but you can also share it with others. In effect, any device that accesses your data in the cloud also becomes yours._ Cloud computing is task-centric. Instead of focusing on the application and what it can do, the focus is on what you nee

36、d done and how the application can do it for you. Traditional applicationsword processing, spreadsheets, email, and so onare becoming less important than the documents they create.PART 2 Understanding Cloud Computing_ Cloud computing is powerful. Connecting hundreds or thousands of computers togethe

37、r in a cloud creates a wealth of computing power impossible with a single desktop PC._ Cloud computing is accessible. Because data is stored in the cloud, users can instantly retrieve more information from multiple repositories. Youre not limited to a single source of data, as you are with a desktop

38、 PC._ Cloud computing is intelligent. With all the various data stored on the computers in a cloud, data mining and analysis are necessary to access that information in an intelligent manner._ Cloud computing is programmable. Many of the tasks necessary with cloud computing must be automated. For ex

39、ample, to protect the integrity of the data, information stored on a single computer in the cloud must be replicated on other computers in the cloud. If that one computer goes offline, the clouds programming automatically redistributesthat computers data to a new computer in the cloud.All these defi

40、nitions behind us, what constitutes cloud computing in the real world?As youll learn throughout this book, a raft of web-hosted, Internet-accessible,Group-collaborative applications are currently available, with many more on the way. Perhaps the best and most popular examples of cloud computing appl

41、ications today are the Google family of applicationsGoogle Docs & Spreadsheets, Google Calendar, Gmail, Picasa, and the like. All of these applications are hosted on Googles servers, are accessible to any user with an Internet connection, and can be used for group collaboration from anywhere in

42、the world.In short, cloud computing enables a shift from the computer to the user, from applications to tasks, and from isolated data to data that can be accessed from anywhere and shared with anyone. The user no longer has to take on the task of data management; he doesnt even have to remember wher

43、e the data is. All that matters is that the data is in the cloud, and thus immediately available to that user and to other authorized users.From Collaboration to the Cloud: A Short History of Cloud ComputingCloud computing has as its antecedents both client/server computing and peer-to-peer distribu

44、ted computing. Its all a matter of how centralized storage facilitates collaboration and how multiple computers work together to increase computing power.Client/Server Computing: Centralized Applications and StorageIn the antediluvian days of computing (pre-1980 or so), everything operated on the cl

45、ient/server model. All the software applications, all the data, and all the control resided on huge mainframe computers, otherwise known as servers. If a user wanted to access specific data or run a program, he had to connect to the mainframe, gain appropriate access, and then do his business while

46、essentially “renting” the program or data from the server.Users connected to the server via a computer terminal, sometimes called a workstation or client. This computer was sometimes called a dumb terminal because it didnt have a lot (if any!) memory, storage space, or processing power. It was merel

47、y a device that connected the user to and enabled him to use the mainframe computer.Users accessed the mainframe only when granted permission, and the information technology (IT) staff werent in the habit of handing out access casually. Even on a mainframe computer, processing power is limitedand th

48、e IT staff were the guardians of that power. Access was not immediate, nor could two users access the same data at the same time.Beyond that, users pretty much had to take whatever the IT staff gave themwith no variations. Want to customize a report to show only a subset of the normal information? C

49、ant do it. Want to create a new report to look at some new data? You cant do it, although the IT staff canbut on their schedule, which might be weeks from now.The fact is, when multiple people are sharing a single computer, even if that computer is a huge mainframe, you have to wait your turn. Need

50、to rerun a financial report? No problemif you dont mind waiting until this afternoon, or tomorrow morning. There isnt always immediate access in a client/server environment, and seldom is there immediate gratification.So the client/server model, while providing similar centralized storage, differedf

51、rom cloud computing in that it did not have a user-centric focus; with client/server computing, all the control rested with the mainframeand with the guardians of that single computer. It was not a user-enabling environment.Peer-to-Peer Computing: Sharing ResourcesAs you can imagine, accessing a cli

52、ent/server system was kind of a “hurry up and wait” experience. The server part of the system also created a huge bottleneck. All communications between computers had to go through the server first, however inefficient that might be.The obvious need to connect one computer to another without first h

53、itting the server led to the development of peer-to-peer (P2P) computing. P2P computing defines a network architecture in which each computer has equivalent capabilities and responsibilities. This is in contrast to the traditional client/server network architecture, in which one or more computers ar

54、e dedicated to serving the others. (This relationship is sometimes characterized as a master/slave relationship, with the central server as the master and the client computer as the slave.)P2P was an equalizing concept. In the P2P environment, every computer is a client and a server; there are no ma

55、sters and slaves. By recognizing all computers on the network as peers, P2P enables direct exchange of resources and services. There is no need for a central server; because any computer can function in that capacity when called on to do so.P2P was also a decentralizing concept. Control is decentral

56、ized, with all computers functioning as equals. Content is also dispersed among the various peer computers. No centralized server is assigned to host the available resources and services.Perhaps the most notable implementation of P2P computing is the Internet. Many of todays users forget (or never k

57、new) that the Internet was initially conceived, under its original ARPAnet guise, as a peer-to-peer system that would share computing resources across the United States. The various ARPAnet sitesand there werent many of themwere connected together not as clients and servers, but as equals.The P2P na

58、ture of the early Internet was best exemplified by the Usenet network. Usenet, which was created back in 1979, was a network of computers (accessed via the Internet), each of which hosted the entire contents of the network. Messages were propagated between the peer computers; users connecting to any single Usenet server had access to all (or substantially all) the messages posted to each individual server. Although the users connection to the Usenet server was of the traditional client/server nature, the relationship between the Usenet servers was d