An Introduction to XML: The Basics Part 1

hi and welcome to introduction to XML part of IBM's technical briefing series you're thinking about getting started with XML and you're wondering where to begin and maybe even why for starters XML is of the core of all web development today it is pervasive it's a good guess that it's being used in many of today's popular sites from new sites to social media it's also used in much of IBM's product and web development as an evergreen technology that drives open standards and open development XML is also at the core of many current approaches and technologies you may be familiar with including web 2.0 Ajax and web services so what is XML extensible markup language helps information systems share structured data while HTML tells browsers how to present information for human use XML is a meta language giving meaning to data that other applications can use in short information about other information it is application and platform independent it's flexible for use with structured unstructured and semi-structured data it's extensible meaning that new tags ordering and processing methods can be created and it allows users to define their own tags there are many advantages of using XML including that it's a simpler version of standard generalized markup language it's easy to understand and read it's supported by a large number of platforms and it's used across open standards that are available today let's take a look at a simple XML example to understand what XML is it may be easier to start with a quick look at HTML here's a simple document created in HTML we've got a title menu and item soup and the second item 499 the price of the soup as you can see we've also assigned some formatting to these items and H 1 and H 4 heading and here is our HTML document in a web browser now let's create a document in XML first we identify the document as being an XML document then we've input the same information the title menu as well as listing the item name soup and the cost for 99 let's look at our XML document in a browser there's an expandable hierarchical tree structure with attributes but unlike the HTML which affects the presentation layer which we see in the web browser in XML were not assigning any style information yet but creating attributes for the items on our menu the item soup at a cost of $4.99 now let's have a look at some XML basics we'll start with some components declaration tags elements attributes and comments declaration is the first line in an XML document it provides information that is valuable to the parser although it is optional it is recommended it contains three name value pairs version encoding and standalone just like an HTML in XML tags are bits of code between angled brackets tags for example the start and end tag are used in XML to define elements tags and data are stored together and data is self descriptive and easy to understand elements are the basic building blocks of an XML file elements are the text between a start and end tag documents contain one root element but can also contain several nested elements attributes provide additional information about the elements they can be stored as name-value pairs using single or double quotes to encode values and attribute names are unique within the same element comments can be used to provide additional information anywhere in the document used within a start and end tag contents inside comments are not parsed now let's have a brief look at other concepts important in XML starting with schemas parsers editors and standards schemas describe the structure and content of an XML document in a way that's consistent across a class of documents this allows schemas to define a common vocabulary for applications to exchange data many XML schema languages have been developed to express specific models including document type definition and XML schema from the World Wide Web Consortium organizations as well as entire industries have standardized xml schemas to promote the exchange of data and they are continually evolving these schemas to meet changing business needs these efforts include schemas and the insurance and financial industries as well as in retail healthcare and standards such as data for authoring maintaining and publishing documentation various types of xml standards have been established by key organizations such as Oasis core standards such as XPath and XML schema form the basis of what is expressed in an XML document processing standards such as xforms and the simple API for XML relate to XML processing by developers key vocabularies also known as applications our language is based on XML well-known vocabularies include xquery and atom parsers read and process the content of an XML document push-and-pull parsers are event-based in poll parsing events are generated by the application whereas in push parsing events are controlled by the parser there are many free XML parsers available today including tools from IBM developers frequently use text and graphical editors to create or modify XML code popular editors such as edit X and XML copy editor can save time and minimize coding by providing visual features to perform tasks xml is central to web development today as a foundation technology for many web 2.0 technologies and techniques including rss/atom and ajax it provides a platform for integrating user-generated content generally associated with web 2.0 including blogs wiki's and forums besides end-user applications and services XML is also important in web services that run behind the scenes from simple functions to complex business processes XML provides a framework for creating specialized languages for complex interactions between clients and services such as soap and WSDL in this module of an introduction to XML we took a look at what XML is the advantages of using XML XML basics and some xml concepts join us in future modules as we take a closer look at xml managing xml data and XML and web 2.0 and 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Keywords: ibm, developerworks, xml, web, ajax, rss, web_2.0

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Length: 8min 2sec (482 seconds)

Published: Mon Jan 25 2010