Why Should I Care about XML?

Why Should I Care about XML?

As a developer, you cannot escape from XML when developing applications—be it simply reading an XML configuration file on application start-up, sharing data between applications on different platforms, or creating a data-driven application using XSLT to render Web pages dynamically. XML has become a core development skill within enterprises, and hence an understanding of the System.Xml namespace within the .NET Framework is essential for application development.

XML is a versatile metadata language, capable of marking up the information content of diverse data sources. This includes structured and semi-structured documents, relational databases, and object repositories. It is not only useful for describing document formats but also suitable for describing structured data. Examples of structured data include information that is typically contained in spreadsheets, configuration files, and relational databases. Examples of semi-structured data are medical reports, documentation manuals, and e-mail.

XML has advantages over previous data formats in that it can easily represent both tabular data, such as relational data from a database, and semi-structured data, such as a Web page or business document. Other formats, such as CSV or EDI, are not as flexible. XML is also easy to handle because it is just text that often requires only simple string manipulation —significantly lowering the bar for working with it. This has led to the widespread adoption of XML as the lingua franca for information interchange. Figure details some typical scenarios for XML with examples.

Since XML has broken down the walls between disparate systems, what we need now are efficient mechanisms for moving this data around and accessing it. XML Web Services enables the transport of XML, but this is only one part of the picture. Accessing XML from storage is even more significant because most meaningful applications need to write the data to a persistent state—and relational databases are without doubt the best choice. Relational databases are unlikely to be replaced as the primary storage mechanism for data, including XML. In fact, all the major databases, including SQL Server, are embracing XML as a native storage type, making it easier to work with. Hence, getting XML data into and out of storage needs to be made easier and more flexible.

So why do you need to care about XML? Because it is now the primary form of data representation and interchange. The XML data model is becoming the predominant way of representing all types of data, not just structured data that easily fits into a relational database. You need to learn to work with XML and understand the significance of the XML data model, since it is now pervasive in application development.