The W3C said XML is "Common Syntax" in the Structure of Expression Data.
Structured data refers to its content, meaning, or application of data being labeled.
By this structure, content and manifestation are separated.
The same XML source document is only written once, can be expressed in different ways: On the computer screen, on the mobile phone display, translate the speech on the device that serve the blind service, and so on. (Huh, web page " Good at 800x600 resolution "prompt, forever)
Wen Yu Note: Wow, and Document / View have the wonderful work
Website builders don't have to indicate where it shows, but indicates the structure of the document. For example, you can explain the title of the document, the author, the list of related documents, and so on. Then, any device with XML browser (handset / Top box / PC) can give the document version that is best for it.
Wen Yu Note: 咦? Is there a different 〖.xsl file on different devices?
XML seizes content and manifestation, and web builders need new ways to control design, display, and output.
Style Sheet is a question. Currently, there are three "style sheets" available for XML:
Cascading Style Sheets (CSS)
Extensible Style Language (XSL)
Document Style Semantics and Specification Language (DSSSL).
CSS may not be strong enough for professional publishers.
DSSSL, an ISO standard popular in high-end publishers using SGML. However, DSSL is complex, very useful on the web.
XSL, style sheet written in XML. Xsl is more powerful than CSS.
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HTML is convenient for "people" and "people" communication, but the computer does not help you manage information, this is just the primary stage of the network.
But XML makes "machine" can talk, can automatically process information.
XML developers will tell you that XML is not a language, but a system defining other languages (such as CDF).
Channel Definition Format (CDF)
Open Software Description (OSD)
CDF and OSD are two XML applications supported by Microsoft.
Through its XML parser, Microsoft's IE 4.0 read CDF files to drive and control the pages brought by push the channel ("Technology").
OSD is a vocabulary for describing software components with grammar, versions, versions, and platforms.
OSD describes the characteristics of a component, and how to install the part onto the computer. It can be used to download a complete package.
Resource Definition Format (RDF)
Resource Description Framework (RDF) is an application: data modeling using XML syntax.
RDF is a description and access data method. This means that RDF is data on data, or metadata.
Wen Yu Note: Wow, metadata, data about data! do not understand? Employees "production" software, and logistics is only managed by employees!
--------------------------------- XML parser ------------- ---------------
Tools for reading XML documents are generally called XML parsers, although it is more formal names being an XML processor.
The XML processor transmits the data to the application to make production, publish, query, or display.
XML does not provide an API, it just passes the data to the application.
Netscape and Microsoft have included the XML parser in its browser.
----------------------------------Cross-platform-------------- ----------------
XML may become a way to exchange information on a database of different vendors.
Various possibilities are awesome, which is a significant reason why there is so much excitement around XML. XML will apply in several different ways. One is exchanged data between men, such as from the web server To the user's browser. The other is to exchange data between different applications, or exchange data between machines.
In these cases, you may need a three-layer architecture: the backend database, the intermediate layer server for the processing logic of the data, and the client that further displays and processes the data.
---------------------------------- DTD & Schema ------------- ---------------
Industrial or organizations want to use XML for data exchange can define their own DTD. If an organization wants to use XML to identify the document only internally, it can create its own private DTD.
Some vendors, including Microsoft, have proposed a method of replacing DTD, called Schema. Different from DTD, Schema can define data types. This method obviously has its advantages, especially for applications, objects, or databases data transmission.
---------------------------------- XML & Java ------------- ---------------
The fixed marker collection and HTML semantic barren make Java applications have been greatly limited. Therefore, the rich information in the data source is not a unified representation. XML is fully qualified for this job. XML really makes Java Have a place of use
Now there is a customer (Client) for developing advanced network applications. It is directly submitted to the client browser after obtaining XML information. Therefore, a client based on Java virtual machine (JVM) is no longer a unique choice.
Sun recognizes that there is no Java virtual machine XML and can communicate with clients, but it thinks XML needs Java to play its potential.
XML can create open data that does not depend on platform, language or restriction formatting protocol. If it is widely used, XML can become a broad standard of communication with the content and the client object. This seems to be very similar to Java, at least a content platform. It is the role of XML attracted Microsoft, which has always been disdaining Java.
XML and Java are perfect because each other is very complementary. XML helps to separate platforms, easy to extract information documents and data. Java helps independent platforms, easy to handle object-oriented application software solutions.
