java和internet計(jì)算機(jī)專(zhuān)業(yè)畢業(yè)設(shè)計(jì)外文翻譯-免費(fèi)閱讀
【正文】 此外講JavaScript的書(shū)可能要比其它語(yǔ)言的都多，而且有些工具還能自動(dòng)生成包括JavaScript程序的頁(yè)面。然而，腳本語(yǔ)言也許能解決百分之十的客戶端編程的問(wèn)題。插件對(duì)于客戶端編程的價(jià)值在于，它能讓專(zhuān)家級(jí)的程序員開(kāi)發(fā)一種新的語(yǔ)言，并且不經(jīng)開(kāi)發(fā)商的同意，就把這種語(yǔ)言加進(jìn)瀏覽器里。最后，你還得寫(xiě)程序，還要解決一串讓人眼花繚亂的問(wèn)題，還是提供客戶端編程的解決方案。而且，毫無(wú)疑問(wèn)你肯定做過(guò)像填寫(xiě)表格這種簡(jiǎn)單的事。Perl是最常用的，因?yàn)樗O(shè)計(jì)的目的就是為了處理和解釋文本，所以不論服務(wù)器用的是那種處理器，或是那種操作系統(tǒng)，都能安裝Perl。客戶端編程Web最初的服務(wù)器——瀏覽器設(shè)計(jì)提供了互動(dòng)內(nèi)容，但是這種互動(dòng)性是完全建立在服務(wù)器之上的。有時(shí)可能會(huì)花幾秒鐘，甚至是幾分鐘，才會(huì)發(fā)現(xiàn)提交的請(qǐng)求里面有一個(gè)拼寫(xiě)錯(cuò)誤。最初這只是個(gè)關(guān)向過(guò)程。但還有更重要的：大約有一半的開(kāi)發(fā)項(xiàng)目都是基于客戶/服務(wù)器架構(gòu)的。此外，通常系統(tǒng)還允許客戶往服務(wù)器里插入新的數(shù)據(jù)?？蛻?服務(wù)器系統(tǒng)客戶機(jī)/服務(wù)器系統(tǒng)的主要思想是，你有一個(gè)中央信息庫(kù)———通常是保存在數(shù)據(jù)庫(kù)中的一些信息———要根據(jù)需要，把它們分配給某些人或機(jī)器。原文來(lái)源：(美)Bruce Ecket. Thinking in JAVA第三版. 2003Java and the InternetIf Java is, in fact, yet another puter programming language, you may question why it is so important and why it is being promoted as a revolutionary step in puter programming. The answer isn’t immediately obvious if you’re ing from a traditional programming perspective. Although Java is very useful for solving traditional standalone programming problems, it is also important because it will solve programming problems on the World Wide Web.What is the Web?The Web can seem a bit of a mystery at first, with all this talk of “surfing,” “presence,” and “home pages.” It’s helpful to step back and see what it really is, but to do this you must understand client/server systems, another aspect of puting that’s full of confusing issues.Client/Server putingThe primary idea of a client/server system is that you have a central repository of information—some kind of data, often in a database—that you want to distribute on demand to some set of people or machines. A key to the client/server concept is that the repository of information is centrally located so that it can be changed and so that those changes will propagate out to the information consumers. Taken together, the information repository, the software that distributes the information and the machine where the information and software reside is called the server. The software that resides on the remote machine, municates with the server, fetches the information, processes it, and then displays it on the remote machine is called the client.The basic concept of client/server puting, then, is not so plicated. The problems arise because you have a single server trying to serve many clients at once. Generally, a database management system is involved, so the designer “balances” the layout of data into tables for optimal use. In addition, systems often allow a client to insert new information into a server. This means you must ensure that one client’s new data doesn’t walk over another client’s new data, or that data isn’t lost in the process of adding it to the database (this is called transaction processing). As client software changes, it must be built, debugged, and installed on the client machines, which turns out to be more plicated and expensive than you might think. It’s especially problematic to support multiple types of puters and operating systems. Finally, there’s the allimportant performance issue: You might have hundreds of clients making requests of your server at any one time, so any small delay is crucial. To minimize latency, programmers work hard to offload processing tasks, often to the client machine, but sometimes to other machines at the server site, using socalled middlewa
教學(xué)課件相關(guān)推薦
鄂ICP備17016276號(hào)-1