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This tutorial will teach you the basics of XML. The tutorial is divided into sections such as in this tutorial, please notify us at [email protected] XML Tutorial in PDF - Learn XML in simple and easy steps starting from basic to advanced concepts with examples including Overview, XML document syntax. xml version="" encoding="UTF-8"?> Belgian Waffles $ Two of our famous .
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Basic XML Concepts. 3. „XML is the cure for your data exchange, information pdf">. Parsing XML. A Basic XML Document. Differences Between XML and HTML. Common Mistakes. White Space. Closing Tags. Nesting Tags. Root Element. An XML Tutorial. JTC1/ depend upon XML technologies in the future! . PDF. • XML Schema an alternative to a DTD and used to validate.
A minus sign in front of a node indicates that the node contains other nodes. If you click the minus sign, Internet Explorer will collapse all the child nodes belonging to that node, as shown in Figure 1. Collapsing nodes displaying in Internet Explorer. View larger image. The little plus sign next to the first product node indicates that the node has children.
Clicking on the plus sign will expand any nodes under that particular node.
In this way, you can easily display the parts of the document on which you want to focus. Now, open your XML document in any text editing tool and scroll down to the cost node of the second product.
You should see an error message that looks like the one pictured in Figure 1. Error message displaying in Internet Explorer. Furthermore, it provides a nice visual of the offending line, a little arrow pointing to the spot at which the parser thinks the problem arose.
Because Internet Explorer uses a non-validating parser by default remember, this means it only cares about well-formedness rules , it runs into problems at the end tag. You now have to backtrack to find out why that particular end tag caused such a problem. Open your XML document in an editor once more, and fix the problem we introduced above.
Save your work and reload your browser. You should see an error message similar to the one shown in Figure 1. Debugging a more complex error. At first glance, this error message seems a bit more obscure than the previous one. However, look closely and what do you see?
Firefox is a popular open-source browser, and at the time this book went to print the latest version was 1. You can download a free copy from the Mozilla website. How do you do that? Well, there are a couple of options, listed below. All you have to do is visit the appropriate page, upload your document, and the parser will validate it.
Here is the most popular online parser. Viewing raw XML in Firefox. Using a Local Validating Parser Sometimes, it may be impractical to use a Website to validate your XML because of issues relating to connectivity, privacy, or security. Just download the package and install it by following the instructions provided. Be warned, however, that you will have to know something about working with Java tools and files before you can get this one installed successfully.
This checks for well-formedness if the document has no DTD, and for well-formedness and validity if a DTD is specified.
Results of the validation will appear under the Results area, as illustrated in Figure 1. For most purposes, an online resource will do the job nicely. If you work in a company that has an established software development group, chances are that one of the XML-savvy developers has already set up a good validating parser.
This project will help ground your skills as you obtain firsthand experience with practical XML development techniques, issues, and processes. It usually consists of the following components: A data back-end comprising XML or database tables that contains all your articles, news stories, images, and other content.
A data display component — usually templates or other pages — onto which your articles, images, etc. A data administration component. This usually comprises easy-to-use HTML forms that allow site administrators to create, edit, publish, and delete articles in some kind of secure workflow. Requirements Gathering Before you build any kind of CMS, first you must gather information that defines the basic requirements for the project.
The goal of the CMS is to make things easier for those who need to develop and run the site. And making things easier means having to do more homework beforehand!
Although you may groan at the thought of this kind of exercise, a set of well-defined requirements can make the project run a lot more smoothly. What kind of requirements do we need to gather? Essentially, requirements fall into three major categories: What kind of content will the CMS handle?
How is each type of content broken down? Who will be visiting the site, and what behaviors do these users expect to find? For example, will they want to browse a hierarchical list of articles, search for articles by keyword, see links to related articles, or all three?
What do the site administrators need to do? For example, they may need to log in securely, create content, edit content, publish content, and delete content. If your CMS will provide different roles for administrative users — such as site administrators, editors, and writers — your system will become more complex. In the world of XML, each of these different types of content is, naturally enough, called a document type. You also have to know how each of these content types will break out into its separate components, or metadata.
Each article, for instance, will have various pieces of metadata, such as a headline, author name, and keywords, each of which the CMS needs to track. The final challenge — to define various types of metadata — can be a blessing in disguise. In my experience, once people grasp the importance of metadata, they race off in every direction and collect every single piece of metadata they can find about a given content type.
For example, the client might start to track the date on which an article is first drafted. When was it first published? When should it automatically be removed from the site, or archived?
How is this document uniquely identified in the system? Who holds the copyright to it?
What other content is it related to? Which keywords describe the content for indexing or search purposes in other words, how do we find the content? Who should have access to the content the entire public, only site subscribers, or company staff?
Does the CMS view an article body as being separate from headings and paragraphs, or are all these items seen as one big lump of XML? Gathering metadata can be very tricky. At first glance, we could say that all of our articles should contain elements for author name and email address, and leave it at that.
However, we may later decide that we want site visitors to search or browse articles by author. You can create element names for individual documents or for document sets. You can craft the rules for how the elements fit together based on your specific needs. You can be very specific or keep element names more generic. You can create rules for what each element is allowed to contain and make these rules strict, lax, or something in between.
Just be sure to create elements that identify the parts of your documents that you feel are important. Because this declaration must be first in the file, if you plan to combine smaller XML files into a larger file, you might want to omit this optional information. Create your root element The root element's beginning and end tags surround your XML document's content. 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.