XML: The spring of electronic commerce

xml| e-commerce Anyone who has browsed the Web page must know HTML. It is the advent of HTML that will have the Internet colorful today.

HTML is out of the business, e-commerce calls Spring

HTML (Hyper text Markup Language, hypertext language) is a Web language developed by the company. Because of its simplicity and ease of use, HTML is quickly becoming a popular concern and a standard web language on the Internet, and continues to this day.

The degree of reuse of HTML is understandable at the time of the Internet. Because of the low level of computer technology at the time, the browser simply could not explain the more complex web language, in this case, HTML is functionally basic to meet the needs of the time. Many large enterprises abroad, quickly set up their own websites, display their products (or services), business management, corporate culture, etc., but only for the show. Enterprise managers did not think that the development of the Internet will be so fast, but also did not think of the emergence of "e-commerce" wave, the Internet into the economic era.

In recent years, with the application of the Web more and more extensive and in-depth, people gradually feel that the HTML is not enough, HTML too simple syntax seriously hinder the use of it to perform complex forms. Despite the introduction of a new version of HTML (the latest version of the HTML4.0, released in 1999), it never met the growing demand.

The emergence of e-commerce, enterprises and enterprises in the Internet frequently meet, the exchange between enterprises more and more important to each other data exchange needs more and more, however, the HTML is too simple syntax, limited labels severely restricts the enterprise through the Web data exchange. Although people want to upgrade the HTML to meet the needs of the enterprise, but because of the beginning of HTML development "limited tag" the nature of not able to change, even the new version of HTML can not solve the demand problem. There is a need for a line and an effective solution to the defects of HTML to meet the development of E-commerce.

In recent years, with the development of computer technology, it has been possible to achieve a much more sophisticated browser than the beginning of HTML development, and computer hardware can handle more complex programs, so it is both necessary and possible to develop a new web language ...

The XML developed by the consortium is breaking into the web world in the voice of this demand. XML, as a new generation of web language, will revolutionize the application of E-commerce based on Web, because XML provides a complete solution for the portability of web pages and the independence of the platform, the compatibility of the system, the data interactivity, the integration of resources and the logistics management, etc.

the affinity between SGML, HTML, and XML

In fact, there is already a world standard markup language, can be used to define a certain type of file format flags, solve the confusion of HTML, that is SGML (standard Universal Markup Language). It is an international standard (ISO 8879) used to describe and define structured electronic documents that were developed in 1980. However, because SGML is too detailed and complex, it has not been widely adopted.

It is not surprising that there are few people in the country who know SGML, because SGML is not widely used in China, although it is not unfamiliar to SGML in the publishing industry. In fact, the application of foreign gaml has penetrated into various fields, such as the European Institute of Atomic Nuclei in Switzerland, Oxford University Press, the United States Securities Commission, the United States Department of Defense and other applications of SGML for information data exchange or print publishing.

SGML is a computer language that deals with electronic documents, which, as the ISO8879 Standard, is independent of any computer and system, and its documents are presented in such a way that it can be used in multiple ways to ensure that documents are exchanged between heterogeneous machines.

Over the years, SGML in China gradually received attention, a group of people in the National Library is committed to promoting the application of SGML in China, in addition to publishing industry, SGML successfully applied to the research of Digital library, is attracting worldwide attention.

Although SGML has the advantage of processing files in objects (object), it can theoretically make up for HTML flaws. However, because of its development earlier than the birth of the Web, the application in the Web environment, such as the 01SGML standard is too strict, too complex 02SGML does not support the link standard 03SGML does not support the layout of the fundamental problems, so that SGML directly applied to the Web is very difficult.

HTML is a markup language, or it can be a format file (formatted text by tags) because HTML is developed on the basis of SGML standards and applied to the Web.

When we browse (browser for Microsoft IE) a Web page, through the submenu bar view \ Source file can view the source code of the Web page. In the source code we can find that HTML is made up of <HTML>, <TITLE>, <BODY>, <TABLE> and many other tags, the browser in the interpretation of the page in the source before the part of the discovery

<HTML>
<HEAD>
<TITLE> This is an HTML document </HTML>
</HEAD>
<body bgcolor= "#FFFFFF" >
<H1> display content through tags </H1>
</BODY>
</HTML>

As you can see from the above code snippet, the content of the web is represented by the attributes of HTML tags or the text between tags, such as: <body bgcolor= "#FFFFFF" >, <TITLE> this is an HTML document </title Browsers are making the Web colorful by interpreting the code for these limited tags in HTML.

HTML is easy to use, because of its simple syntax, it is easy to develop HTML editing software. But its biggest limitation also lies in its too simple syntax and the limited label mechanism, causes the HTML to be limited in the application scope mainly has:

1, the available label types are limited, can not accurately describe the information;
2, the data format can not express its intrinsic significance;
3, can not express the deep information structure, so not suitable for a large number of documents storage;
4, to remove the electronic reading, the use of HTML for other areas of application, poor performance;
5, the information form of HTML is not suitable for reuse;
6, despise the concept of printed pages;
7, the fine arrangement designation is impossible;
8. The results of Full-text search are not accurate;
9, the function of HTML and Web browser to strengthen the results, resulting in the Web browser interchange function of the part of the disappearance;

Because of the limited HTML tag, it can only represent the content from the form, but it is powerless to express the content in the sense. The:<p>100</p> in the example HTML code can only be interpreted as a number 100, but it means 100 people, 100 tons, 100 dollars, but it is unknown. But the electronic data of electronic commerce on the internet is meaningful, ￥rmb100 and $ are the same in value, but there is difference in the sense, the data sharing and data exchange between enterprises must distinguish the data from the meaning. Therefore, in the era of electronic commerce, where enterprises communicate frequently through the Internet, the demand for data exchange cannot be suppressed, because of the defects of HTML itself, the poor can only achieve "digital exchange" rather than "data exchange".

xml--Technology of Future network

Just as the HTML was at its wit's end, a new generation of web-based technology--xml was born.

1996-19,976, the World Wide WEB CONSORTIUM,WWW Consortium developed XML (extensible Markup Language, Extensible Markup Language) and officially released the XML1.0 version in February 1998. Although XML is widely recognized as a technology, the consortium is a high-profile organization that absorbs major software vendors and research institutions as members, and in order to avoid anti-competitive lawsuits in U.S. law, the consortium has used these fully reviewed technical documents as recommended documents rather than mandatory standards.

HTML is an application of SGML on the web, and XML is the best child born from SGML. XML is a subset of SGML, so XML inherits most of SGML's features and inherits the meta language features of SGML. That is, XML as an application language can be used both directly on the web and in the development of the application language, and is superior to SGML. XML is an extension of SGML for the purpose of web utilization to solve HTML defects, and deletes and changes the functionality that is part of SGML that affects its utility. So XML achieves the function of sgml80% with 20% SGML difficulty.

The main design goals of XML are:

1, can be used directly on the web;
2, wide range of applications available;
3, try to maintain and SGML interchangeability;
4, processing the XML program can be simply written;
5, XML documents should have a high readability;
6, strict but not complex rules;
7, remove the selected option function, reduce the processing load of the application;
8, not to reduce the number of labels as an important work.

The x--extensible in XML is interpreted as "extensible," which is where XML is superior to HTML-allowing users to build their own tags, rather than using certain limited tags!

? XML version= "1.0" encoding= "GB2313"?>
< bookstore >
< books >
< title type = "Economy" > Western Economics </title >
< Price currency = "RMB" unit = "Yuan" >60</price >
< author nationality = "China" > Gao Hongye </author >
<ISDN>7-300-00337/F-991</ISDN>
< publishing year = "February 2000" edition = "Second Edition" > Renmin University Press </Press >
</Books >
</Bookstore >

As above is a simple source code for XML files. It is obvious that its manifesto is not the same as HTML, which allows users to freely create labels and their attributes, and to support Chinese tags.

To fill the gaps in HTML and to describe the meaning of electronic data, XML follows the mechanism of SGML's user-defined label. Therefore, XML represents the electronic data content more intuitive and effective, and can be easily used for electronic data exchange between enterprises. such as < price currency = "RMB" unit = "Yuan" >60</price > It can be seen that the commodity "price" is "60" "Yuan" "People coin", compared to HTML to display more intuitive. It also allows for two-direction communication between enterprises, that is, a bridge between two or more enterprises in different database formats, different database structures, and electronic data interchange.

Why is it so difficult to exchange electronic data between companies? Because there are many suppliers of database software for enterprises, compared with the size of SQL, Oracle, PowerBuilder, Informix, and so on, they are different technology, to direct electronic data exchange near impossible, and even if the enterprise can use the same database, The structure of each database is different, and the electronic data exchange can not be directly carried out. Therefore, due to the scalability of XML, the task of electronic data interchange between the enterprises ' respective databases can be well accomplished.

Another reason XML is a good way to represent electronic data and make it very good for exchange between businesses is that XML supports Chinese tags.

Say XML supports Chinese tags, and more precisely XML supports non-English character sets. Because the Internet makes the trade of information technology truly global, a new generation of web languages is necessary to support non-English character sets. In view of this, XML supports Unicode (uniform character encoding), which contains a representation text character system for computer processing of 50000 of the world's known written languages. The most recent Unicode3.0 version is in line with the international standard set of ISO/IEC 10646-1:2000, which uses double-byte or 16-bit notation characters, which can be numbered for most known character sets, including technology and numeric symbols, and Unicode provides more than 65,000 characters of code. Truly globalization of XML.

When the browser (IE) runs an XML file, the declaration--< the XML file is found in its first row;? Xml= "1.0" encoding= "..."?>, the file is interpreted as XML, rather than the HTML standard. If there is no error in the XML file, the browser will display the contents of the file in tree form. This facilitates browsing the contents of the XML file.

related technologies in XML

We say that XML will be the base technology for the next generation of web, not just because XML has the above characteristics. In order to make the specification of XML complete, XML has been used in SGML's DTD technology (optional).

While the extensible nature of XML has brought a lot of advantages, in some cases, this lack of specification extensibility tends to make the use of tags without rules, resulting in confusion in the file structure, which is the part of XML in SGML for file types.

A DTD (document type definition: the definition of documents types) defines the name of the document element (the signature), the order in which the elements appear, and the number of times the elements appear, through the element type declaration.
Logically, the XML file is divided into constructs that contain DTDs and constructs that do not contain DTDs, which are referred to as legitimate XML files and structure-complete XML files, respectively. In a legitimate XML document, the DTD lies between the XML declaration and the document element, and it can be in the same entity (file) as the XML declaration, but more as an external instance (an external file) and then referenced separately.

The design of a DTD should first analyze the information that should be processed, when the exchange of information between enterprises and groups is the aim, it should be considered in the aspects of standardization, universality, neutrality and permanence, and secondly, when the file is used only in the company, it should focus on the possibility of its operation, economy, and terminal user interface.

The DTD, in addition to its own document type declaration, consists of a declaration of elements, a list of attributes, an entity declaration and four declarations of the Declaration of Law.

Document Type Manifesto refers to the specific provisions on the various elements of the document represented by the label and the declaration of its hierarchical structure, the attribute declaration of the accessory information, and how to label the implementation value.

The declaration of factor type: the definition of the elements that the XML implementation value can use. Specify the name of the elements, the hierarchy of elements.

Attribute List declaration: Defines an attribute that is attached to an element. What is the attribute of an element, the name of the property, the specified property value, whether the property is specified, and what the default value of the property is.

Entity manifesto: The definition of the XML implementation value and the entity to be exploited in the DTD. To replace the text and text string, to add to the XML stylistic document in the external file, the reference to the entity name used in the designation.

Declaration of notation: a name that is specified in order to recognize the notation of an external file referenced by an entity that uses an notation other than XML.

The DTD is to standardize the XML file structure through its four declarations, so that its structure is unified and rigorous, so as to prevent the electronic data from making mistakes in exchange and causing unnecessary economic loss.

namespace of XML

XML namespaces provide a way to avoid element name collisions.

Because the label names in XML are not fixed, a naming conflict occurs when two different documents describe two different types of elements using the same name. If the two XML documents with the same label name are added together, a tag naming conflict occurs because both documents contain a label with the same name, and the contents and definitions of these two elements are likely to be different. The XML namespace is the use of a tag prefix to create two different types of labels with the same name, avoiding tag name collisions.

The common name Space specification stipulates that the namespace itself should be a Uniform Resource identification number (URI). When a namespace is defined in the start tag of an element, all child elements of the same prefix are associated with the same namespace. A Uniform Resource identification number (URI) is a string that identifies an Internet resource. Typically, a URI is a URL that identifies an Internet domain address. In addition, there are a few types of URIs that are generic resource names (urns). Since we only use an Internet address to identify its name space, we can be sure that our namespaces are unique.

XML file Style technology--css and XSL

We know that content in XML is separate from representation, which allows different users to define data representations according to their needs. In other words, in an XML grammar, a DTD defines the elements, but the meaning of each element and the processing of it are not determined by the DTD. Therefore, when the browser to display XML data, corresponding to the various elements should be used in the font and font size, the problem of display format, must be decided in advance. The designation of a format can be seen as a way to give meaning to XML data. For example, the large size of the XML data is usually the title and so on.

XML available formats specify two languages, CSS (cascading Style Sheets, cascading format table), and XSL (extensible Stylesheet Language, extensible Format language).

The origin of CSS is designed to specify the format of HTML files, and as XML is born, it is versioned to apply to XML documents as well. CSS language is mainly through the XML document tags or attributes to the format of information, so that each label content in a set format displayed in the browser.

CSS can be referenced as an external file, or it can be integrated with XML files, but for ease of management and sharing, it is advocated in principle to be referenced as an external file. When you need a file to manage an XML document, you can place its format table in the entity part of the XML document, and when you want to highlight a particular part, you can take a grammar that describes the part in a separate format. and the CSS style sheet file as an external reference, XML in the browser changes in appearance, just modify the external CSS file can not destroy the structure of XML files, but also greatly simplifies the process of modification and complexity.

XSL is the Dsssl (document style Semantice and specification Language, which specifies the language in which the documents are formatted. An international standard specified in the SGML document format. And CSS functions are based on XML features. In addition to the functions of CSS, XSL can also achieve two functions: 1, the transformation of the file structure, 2, the processing of the designation.

The transformation of the file structure, as a major part of the XSL function, is called SXLT (transformation, transform). Using Sxlt, you can transform an XML file into another XML file as needed and, on the other hand, transform the XML file into an HTML file for browsing and display because of the extensive use of HTML. SXLT Development is intended to be the latter, so that the HTML file browser can display the contents of the XML file. Now, Sxlt can be transformed between files of various types.

Processing, the use of XSL not only allows various transformations to meet different needs, but also adds scripting language to the XSL. The scripting language can be used to deal with such things as the sorting of elements, the operation of words, numerical calculation and counting of elements.

In addition, Xpath-xml match mode (XML pattern Matching), Xlink-xml link language (XML linking Language), Xpointer-xml pointer language (XML pointer Language), X Sd-xml mode (XML Schema), XDR-Data simplification (XML Data Reduced), DOM-Document Object model, Xql-xml query Language (XML Query Language), The XML-related technologies of Sax-xml's simple API (easy API for XML) make the XML world rich and colorful, and make XML apply to all walks of life. The four application advantages of XML are:

(1) When customers need to interact with different data sources, the data may come from different databases, all of which have different complex formats.

(2) Distribution of a large number of operational load on the client, that is, customers can choose and produce different applications to process data according to their own needs, and the server only needs to emit the same XML file.

(3) Displaying the same data in different faces to different users. Similar to the same script, we can use TV dramas, movies, plays, cartoons and other forms of expression. This application will pave the way for the personalized and stylized development of the Web user interface.

(4) The network agent to the information obtained by editing, increase or decrease to meet the needs of individual users.

These applications, inseparable from the relevant XML technology, although some of these technologies exist only in the theoretical stage, or the current browser can not achieve its future function, but the development of XML is unstoppable, its application in E-commerce is inevitable. We can imagine that the cheap xml-edi makes it easy for small and medium-sized enterprises to enjoy the data exchange; the future search engine will be able to search through XML directly to find out the only requirement information that users specify, completely eliminate the garbage part of searching; When using the combination of XML and VRL technology, People can truly observe and touch the products of the enterprise through the display and mouse, and how the concept of education will change after the application of XML in the network distance education is mature ...

xml--The bright future of electronic commerce

As new technology continues to hit the Internet, XML technology will have a significant impact on E-commerce. The human-Computer interactive architecture of XML provides the interactive communication between the user and the computer, using its extensibility and self-describing features, the electronic communication files can be automatically transmitted, processed and stored in the enterprise application, and can be connected to different vendors ' electronic catalogue information in the same user interface. The search for data has become more accurate and rapid, with different systems flowing seamlessly, and data sharing between different Web sites dynamically shared, reinforcing the aggregation of users and systems.

What XML brings is a new vision, a subversion of the concept of the entire e-business architecture, and small and medium-sized enterprises can easily enjoy the benefits of E-commerce. The power of electronic commerce has begun to show, in the foreseeable future, the global economy will certainly be shocked by this online e-commerce, in the wave of E-commerce will come, XML is a new technology can not be ignored.