XML in a Nutshell, 3rd Edition

File Formats

Many single-user desktop applications open and save files. Games store the current state of the game. Word processors store text. Spreadsheets store numbers. Personal finance programs store monetary transactions. What unites these applications is that the data is read and written only at well-defined times, generally when the user selects Save or Open from the File menu. The formats designed for such storage are rarely a simple dump of the objects in-memory. What’s sensible for storage on disk is rarely what makes sense for in-memory manipulation. Instead, special code is written to load and save a custom format that represents the information to be saved.

Most such file formats should be based on XML. It is much easier to invent, define, and use an XML format for such files than to devise some custom binary format. The first advantage is simply the wide availability of tools to parse and write XML. Unlike a custom format, basing your own format on XML means you don’t have to test and debug parsers and serializers. Just use one of the well-tested, well-established, and debugged standard tools like Xerces or MSXML. You write less code, which translates into fewer bugs and faster time to market.

A second advantage to choosing XML for the format is that the files will be more accessible to other tools and developers. They too can use standard parsers to read the files. It may not be immediately obvious to such third parties what all the elements and attributes mean, but ...