1. XML shall be straightforwardly usable over the Internet.

This does not mean that XML should only be used over the Internet, but rather that it should be lightweight and easily usable over the Internet.

2. XML shall support a wide variety of applications.

The idea here is that XML should not be application specific. It can be used over the Internet or in a traditional client/server application. There is no specific technology behind XML, so any technology should be able to use it.

3. It shall be easy to write programs that process XML documents.

Unable to gain wide acceptance for various reasons, many technologies come and go. A major Barrier to wide acceptance is a high level of difficulty or complexity.

The designers of XML wanted to ensure that it would gain rapid acceptance by making it easy for programmers to write XML parsers.

4. XML documents should be human-legible and reasonably clear.

Because XML is text-based and follows a strict but simple formatting methodology, it is extremely easy for a human to get a true sense of what a document means. XML is designed to describe the structure of its contents.

5. XML documents shall be easy to create.

XML documents can be created in a simple text-editor. Now that’s easy!There are other XML guidelines, but since this only is an introduction to XML, these will do for now. The important thing to remember is that XML is simply a file format that can be used for two or more entities to exchange information.

XML documents are hierarchical: they have a single (root) element, which may contain other elements, which may in turn contain other elements, and so on. Documents typically look like a tree structure with branches growing out from the center and finally terminating at some point with content. Elements are often described as having parent and child relationships, in which the parent contains the child element.

XML documents must be properly structured and follow strict syntax rules in order to work correctly. If a document is lacking in either if these areas, the document can’t be parsed.

There are two types of structures in every XML document: logical and physical. The logical structure is the framework for the document and the physical structure is the actual data.

An XML document may consist of three logical parts: a prolog (optional), a document element, and an epilog (optional). The prolog is used to instruct the parser how to interpret the document element. The purpose of the epilog is to provide information pertaining to the preceding data.



No comments:

Post a Comment