java和internet計算機專業(yè)畢業(yè)設(shè)計外文翻譯(存儲版)
【正文】 re. (Middleware is also used to improve maintainability.)The simple idea of distributing information has so many layers of plexity that the whole problem can seem hopelessly enigmatic. And yet it’s crucial: Client/server puting accounts for roughly half of all programming activities. It’s responsible for everything from taking orders and creditcard transactions to the distribution of any kind of data—stock market, scientific, government, you name it. What we’ve e up with in the past is individual solutions to individual problems, inventing a new solution each time. These were hard to create and hard to use, and the user had to learn a new interface for each one. The entire client/server problem needs to be solved in a big way.The Web as a giant serverThe Web is actually one giant client/server system. It’s a bit worse than that, since you have all the servers and clients coexisting on a single network at once. You don’t need to know that, because all you care about is connecting to and interacting with one server at a time (even though you might be hopping around the world in your search for the correct server).Initially it was a simple oneway process. You made a request of a server and it handed you a file, which your machine’s browser software (., the client) would interpret by formatting onto your local machine. But in short order people began wanting to do more than just deliver pages from a server. They wanted full client/server capability so that the client could feed information back to the server, for example, to do database lookups on the server, to add new information to the server, or to place an order (which required more security than the original systems offered). These are the changes we’ve been seeing in the development of the Web.The Web browser was a big step forward: the concept that one piece of information could be displayed on any type of puter without change. However, browsers were still rather primitive and rapidly bogged down by the demands placed on them. They weren’t particularly interactive, and tended to clog up both the server and the Internet because any time you needed to do something that required programming you had to send information back to the server to be processed. It could take many seconds or minutes to find out you had misspelled something in your request. Since the browser was just a viewer it couldn’t perform even the simplest puting tasks. (On the other hand, it was safe, because it couldn’t execute any programs on your local machine that might contain bugs or viruses.)To solve this problem, different approaches have been taken. To begin with, graphics standards have been enhanced to allow better animation and video within browsers. The remainder of the problem can be solved only by incorporating the ability to run programs on the client end, under the browser. This is called clientside programming.Clientside programmingThe Web’s initial serverbrowser design provided for interactive content, but the interactivity was pletely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them. Basic HyperText Markup Language (HTML) contains simple mechanisms for data gathering: textentry b
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