What You Will Learn. This tutorial will give you a solid understanding of XML: What is XML? How does XML work? How can I use XML? What can I use XML for ?. XML stands for Extensible Markup Language and is a text-based markup language You can learn more about XML elements in this chapter: XML Elements. Learning XML shows the purpose of XML markup itself, the CSS and. XSL styling languages, and the XLink and XPointer specifications for creating rich link.
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The rules are easy to learn, and easy to use. All XML Elements Must Have a Closing Tag. In HTML, some elements do not have to have a closing tag: This is. „XML is the cure for your data exchange, information integration, data pdf">. A. How to Learn Using O'Reilly School of Technology Courses. Setting XML In this course, you will learn the fundamentals of XML for use with XML-enabled.
Only one root element is in the file, and you need this "wrapper" to contain it all. See Download for the full XML file.
Listing 1. Name your elements Matching case in tags When you create your XML, be sure that your beginning and end tags match in case. If the case doesn't match, you might get an error when you use or view the XML. Internet Explorer, for example, will not display the file content if the case is mismatched.
Instead, Internet Explorer displays messages about the beginning and end tags not matching.
Here are a few things to note about your naming: Spaces are not allowed in the element names. Names must begin with an alphabetic character, not a number or symbol. After this first character, you can use any combination of letters, numbers and the allowed symbols. Case does not matter, but be consistent to avoid confusion. Listing 2. Nest the elements Nesting is the placement of elements inside other elements. These new elements are called child elements, and the elements that enclose them are their parent elements.
Nesting can be many levels deep in an XML document.
A common syntax error is improper nesting of parent and child elements. Any child element must be completely enclosed between the starting and end tags of its parent element.
Sibling elements must each end before the next sibling begins. The code in Listing 3 shows proper nesting. The tags begin and end without intermingling with other tags. Listing 3. Attributes provide a way to store additional information each time you use an element, varying the attribute value as needed from one instance of an element to another within the same document. Listing 4 shows the XML file as it currently stands.
Listing 4. Consider the details you might add to your documents. Attributes are especially helpful if documents will be sorted—for example, by type of recipe.
Attribute names can include the same characters as element names, with similar rules for omitting spaces and starting names with alphabetic characters.
But consider the aforementioned example of sorting by recipe type. Validation is checking your document's structure against rules for your elements and how you defined child elements for each parent element. This line refers to the DTD or schema your list of elements and rules to be used to validate that document. Listing 5.
Using entities Entities can be phrases of text or special characters. They can point internally or externally. Entities must be declared and expressed properly to avoid errors and to ensure proper display. You cannot typed special characters directly into your content.
To use a symbol in your text, you must set it up as an entity using its character code. You can set up phrases such as a company name as an entity, then type the entity throughout your content. This code identifies the text that stands in for the entity. Listing 6. So he understands XML from the real-world point of view of someone with a job to do.
His first goal is to take on the big questions. First, What is XML?
Ray attacks this question from multiple angles, introducing XML as a general-purpose information storage system, a markup language toolkit, and an open standard or, increasingly, a collection of standards. What can and can t you do with XML? What s the history that led us here? And what tools do you need to get started? Next, he introduces the basic building blocks of XML markup and all XML-derived languages: stuff you ll need to know regardless of your goals.
Through easy examples, you ll understand elements, attributes, entities, and processing instructions -- and how they fit together in a well-formed XML document. Then, it s on to representing information with XML -- in other words, understanding the nature and planning the structure of the documents you ll be using.
Ray starts simply, then builds on his basic examples to discuss narrative documents with text flows, block and inline elements, and titled sections. Once you can handle those, he discusses more complex information modeling, as used in specialized markup languages such as VML. This edition contains an entirely new chapter on XML Schemas -- what he calls the shepherds that keep documents from straying outside of the herd and causing trouble.
Schemas, of course, have become hugely important. This is one of the best plain-English introductions to the topic we ve seen.