XML基础:How Can XML be Used?

How Can XML be Used?

XML is used in many aspects(方面) of web development, often to simplify
(简化) data storage(存储) and sharing(共享).

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XML Separates(分离) Data from HTML

If you need to display dynamic(动态) data in your HTML document, it will take a lot of work to edit the HTML each time the data changes.

With XML, data can be stored in separate XML files. This way you can concentrate on(专心于...) using HTML for layout and display, and be sure that changes in the underlying data will not require any changes to the HTML.

With a few lines of JavaScript, you can read an external XML file and update the data content of your HTML.

You will learn more about this in a later chapter of this tutorial.

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XML Simplifies Data Sharing

In the real world, computer systems and databases contain data in incompatible formats(不协调的格式).

XML data is stored in plain text format. This provides a software- and hardware-independent way of storing data.

This makes it much easier to create data that different applications can share.

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XML Simplifies Data Transport

With XML, data can easily be exchanged between incompatible systems.

One of the most time-consuming(耗时) challenges(挑战) for developers is to exchange(交换) data between incompatible(不协调的) systems over the Internet.

Exchanging data as XML greatly reduces this complexity(复杂性), since the data can be read by different incompatible applications.

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XML Simplifies Platform Changes

Upgrading to(提高到...标准) new systems (hardware or software platforms), is always very time consuming(消耗). Large amounts of data must be converted and incompatible data is often lost.

XML data is stored in text format. This makes it easier to expand(扩展) or upgrade to new operating systems, new applications, or new browsers, without losing data.

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XML Makes Your Data More Available

Since XML is independent of hardware, software and application, XML can make your data more available and useful.

Different applications can access your data, not only in HTML pages, but also from XML data sources.

With XML, your data can be available to all kinds of "reading machines" (Handheld computers, voice machines, news feeds, etc), and make it more available for blind people, or people with other disabilities.


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XML is Used to Create New Internet Languages
A lot of new Internet languages are created with XML.

Here are some examples:

XHTML the latest version of HTML 
WSDL for describing available web services
WAP and WML as markup languages for handheld devices
RSS languages for news feeds
RDF and OWL for describing resources and ontology
SMIL for describing multimedia for the web 

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If Developers Have Sense(意识)

If they DO have sense, future applications will exchange their data in XML.

The future might give us word processors, spreadsheet applications and databases that can read each other's data in a pure text format, without any conversion utilities in between.

We can only pray that all the software vendors will agree.