In this chapter, we look at the use of XML for configuration data. This differs from our XML coverage in other chapters in that we are not using XML to transfer data between applications, or for generating a presentation layer; we are simply using XML to store data. To understand the motivation for using XML for configuration data, you need only write an application that uses extensive properties files, or code a server that is configured via files on a filesystem rather than command-line arguments. In both cases, the format of the files to supply information to the application becomes arbitrary and usually proprietary. The developer working on configuration often decides on a format, codes a file reader, and the application becomes locked into that format forever. Certainly this is not the most long-term view of application programming and development.
As developers and system engineers realized the maintenance problems
that an approach like this can cause (forgetting where a comma
belongs, being unsure what marks a comment, etc.), it became clear
that a standard was needed to represent this type of data that would
not immediately cause an application’s configuration mechanism
to become proprietary. One standard solution that is being used
today, but is still lacking functionality, is
Java properties files and the
class. Introduced in the
Java Development Kit ( JDK) 1.0, these constructs provide a more Java-centric means ...