java对象的介绍英文文献和中文翻译

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Introduction to Object Java and the Internet If Java is, in fact, yet another computer programming language, you may question why it isso important and why it is being promoted as a revolutionary step in computerprogramming. The answer isn’t immediately obvious if you’re coming from a traditionalprogramming perspective. Although Java will solve traditional stand-alone programmingproblems, the reason it is important is that it will also solve programming problems on theWorld Wide Web.43631

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.” There has even been a growing reaction against “Internet-mania,” questioning the economic value and outcome of such a sweeping movement. 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 computing that’s full of confusing issues.

Client/Server computing

The primary idea of a client/server system is that you have a central repository of information – some kind of data, typically 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(s) where the information and software reside is called the server. The software that resides on the remote machine, and that communicates with the server, fetches the information, processes it, and displays it on the remote machine is called the client.

The basic concept of client/server computing, then, is not so complicated. 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 complicated and expensive than you might think. It’s especially problematic to support multiple types of computers and operating systems. Finally, there’s the all-important performance issue: you might have hundreds of clients making requests of your server at any one time, and 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 so-called middleware. (Middleware is also used to improve maintainability.)

So the simple idea of distributing information to people has so many layers of complexity in implementing it that the whole problem can seem hopelessly enigmatic. And yet it’s crucial: client/server computing accounts for roughly half of all programming activities. It’s responsible for everything from taking orders and credit-card transactions to the distribution of any kind of data – stock market, scientific, government – you name it. What we’ve come up with in the past is inpidual solutions to inpidual 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.

对象的介绍Java和因特网

事实上，如果Java还是另外一种电脑编程语言，你可能会质疑，为什么他会如此重要，而且为什么它!751·文~论^文'网www.751com.cn一直被推广为电脑编程革命性的一步。如果你是从一个传统的编程开发视角来看，答案并不会是很显而易见。尽管Java能解决传统的独立编程的一些问题，更重要的原因是它能解决万维网上的一些编程问题。