Tip Although it might seem that the terms tag and element are interchangeable, they’re not.An element includes the opening and closing tags for a tag pair — and everything in between.A tag is just a tag, all by itself.Example : One example of a tag is the opening <p> tag , an example of an element is <p>text</p>.XML also provides numerous ways to translate this information so it looks the way you want it to on-screen.RememberHTML is used to describe the display of data as seen through a Web browser.XML enables you to define and use your own elements and attributes
Note If you validate your XHTML document, you’ll find that you can either include the space before the closing slash or not — your document will validate in either case. The extra space is a browser issue, not a validation issue.
Tip : Both single quotation marks (‘) and double quotation marks (“) are legal in XML and XHTML.
You can convert your HTML to XHTML with ease by using Dave Raggett’s free open-source program, HTML Tidy. The maintenance of HTML Tidy is now provided by Source Forge. Check it out at http://tidy.sourceforge.net/. For a version that’s even easier to use than the original, see the HTML-Kit at www.chami.com/html-kit/.
1. XML For Dummies http://it- slideshares.blogspot.comBook Author : Lucinda Dykes & Ed TittleLecture 4 : Adding XTHML for the Web
2. http://it- slideshares.blogspot.comContents1. HTML, XML, and XHTML2. Comparing XML and HTML3. XHTML Makes the Move to XML Syntax4. Convert a document from HTML to XHTML5. The Role of DOCTYPE Declarations
3. 4.1. HTML, XML, andXHTML HTML, XHTML, and XML represent stages in the development of markup languages. ◦ HTML, designed to display content in Web browsers, came first. ◦ XML, intended for data exchange, came next. ◦ XHTML — which uses the markup tags of HTML and the strict syntax of XML.
4. http://it-4.1.1 What HTML does slideshares.blogspot.combest HTML makes our Web world look pretty. ◦ Such as a personal site that you create for your family. Most Web sites use straight HTML to display data
5. http://it- 1.2 The limits of4. slideshares.blogspot.comHTML HTML was enlisted to perform some pretty specify tasks. ◦ Allow tight control over document display. ◦ Provide the flexibility to describe different, specific types of information and data. ◦ Convey information from a variety of media and in a various formats. ◦ Define complex linking relationships between document. ◦ Publish a single set of information cross a variety of media. Two overarching problems prevent Web designers from achieving this control with HTML: ◦ HTML lacks fine controls. Not include mechanisms for the control. … ◦ Display vary. Problems with browsers that users view web pages (IE, Firefox…) …
6. 4.2. Comparing XML andHTMLHTML are not the same kind of markupXML and language. But XML and HTML both derive from the same parent SGML. ◦ So they must be similar, right ? HTML and XML both use tags and attributes. XML and HTML look similar. HTML defines basic text elements and includes defaults (and more explicit controls) for how text may be displayed in a browser window XML tells us only what each element means. XML says nothing about how elements should or must be displayed — XML separates content and the presentation of that content.
7. 4.2.1 Using XML to describe data XML is not limited to any fixed set of tags or element types. ◦ You can define your own sets of elements and even your own attributes that you may then Document HTML use within your documents. XML Document <Cover><html> <Abstract><p> This book is about the foundations of theBlah blah blah blah blah blah blah blah blah blah Extensible Markup Language (XML)blah blah blah blah blah (XML) and how to use it for your own applications.blobbity blobbity blobitty blah blah blah blah. blah </Abstract>blah blah <AuthorInfo></p> The authors are <Author>Lucinda<p> Dykes</Author> andBlah blah blah Lucinda Dykes blah Ed Tittel. <Author>Ed Tittel</Author>.</p> </AuthorInfo></html> </Cover>
8. 4. 2.2 The benefits of usingHTML It’s quick, easy, and cheap. HTML is way easier than the alternative. Anyone can create an HTML document by using a text editor and a little knowledge. ◦ Even if you don’t know HTML, you can use an HTML editor — a What You See Is What You Get-style (that is, WYSIWYG-style) editor such as FrontPage or Dreamweaver — to produce readable Web pages in minutes.
9. 4.2.3 The benefits ofusing XMLXML seems to be brimming with benefits. ◦ Unlimited element ◦ Structured data ◦ Data exchange ◦ XML complements HTML ◦ XML documents are well formed ◦ Self-describing ◦ Search engines ◦ Updates ◦ User-selected view of data Intelligent XML-based pages that contain human- readable data offer exciting potential for users. A Web designer/developer reaps several benefits from XML as well. The benefits of XML are endless.
10. 4. 3. XHTML Makes the Move toXML Syntax XHTML is the successor to HTML 4.01; in effect, it’s the final version of HTML. XHTML is a clever reformulation of HTML 4 as an application of XML 1.0. Why do we like XHTML? ◦ XHTML documents can be viewed, edited, and validated using XML tools. ◦ Well-formed XHTML documents mean better-structured documents. ◦ XHTML documents can be delivered using different Internet media types and output devices. ◦ Using valid XHTML gives you the best chance of having your document displayed the way you intend.
11. 4. 3.1 Making the switch Making the switch from HTML to XHTML means mastering the rules of XHTML — in particular, XML syntax and structure. You have only a few major rules to get under your belt, but you have to follow them if you want to create a valid XHTML document. ◦ Every tag in an XHTML document must be closed. ◦ Empty elements (elements without content, such as a br tag) must be correctly formatted with a closing slash. ◦ All tags must be nested correctly — the tag you open last must be the tag you close first ◦ All XHTML tags must be written using only lowercase. ◦ All attribute values must be put in quotation marks. An acceptable XML document must be well formed.
12. 4. 3.2 Every element must be closed That all nonempty elements (that is, those that contain actual text) must have a start tag and an end tag. In the case of HTML Is the same as<p>text text text <p>text text text</p> Doing without an end tag just doesn’t fly in XHTML. ◦ You have to add closing paragraph tags where they belong if you want the resulting lines to work right.
13. 4. 3.3 Empty elements must beformatted correctly All nonempty XML elements must use both a start tag and an end tag to be correct. An empty element is a singleton tag (also called an empty tag) that hangs around by itself. ◦ Empty tags in HTML include the <br>, <hr>,<hr>and <img> tags. ◦ The<hr /> hr element looks like this in HTML: ◦ In XHTML, it looks like this:
14. 4. 3.4 Tags must be properly nested The rules of XHTML syntax say that tags must be nested in the correct order. The rule is always to close first what you opened last, working your way Ill formed from the inside to the outside tags.<p>This book was written by <i><b>Dan Brown</i></b>. Well-formed<p>This book was written by <i><b>Dan Brown</b></i>.</p>
15. 4.3.5 Case makes adifference HTML is not case sensitive; XHTML is. ◦ When you use HTML, it doesn’t matter what case you use for elements and attributes. ◦ For example, for the opening body tag, you can use <BODY>, <body>, or even <Body> they all work fine. XHTML, on the other hand, is a bit more finicky about case. ◦ All XHTML elements and attribute names must be in lowercase or your page won’t validate. ◦ Use any case for the value of an attribute
16. 4. 3.6 Attribute values are in quotation marks In XHTML, all attribute values must be in quotation marks. ◦ The following markup works just fine on an HTML page: ◦ You have to add quotation marks around the attribute value<tr align=right> to create valid XHTML.<tr align=”right”> highlights the major rules for XHTML syntax and Table 4-1 shows how markup looks in HTML and XHTML.
17. 4. 4. Converting a documentfrom HTML to XHTML
18. 4. 4. Converting a documentfrom HTML to XHTML
19. 4. 5. The Role of DOCTYPEDeclarations The DOCTYPE declaration serves several purposes: ◦ It allows your page to be validated as XHTML. ◦ It tells the browser which version of which markup language you used to create the page and references the specific DTD for that language. ◦ It enables your page to be displayed properly in Web-standards-compliant browsers. You have three different DOCTYPES to choose among for an XHTML 1.0 document: strict, transitional, and frames.
20. http://it- slideshares.blogspot.com4.6 Summary Understanding the limitations of HTML Comparing HTML with XML Getting the best of both worlds: XHTML Converting HTML to XHTML