XML-GL: A Graphical Query Language for XML Documents

XML now plays an important role in storing, presenting, and exchanging a wide variety of data on the Web. With the growing use of XML, the ability to intelligently query data sources in XML format by using graphical or textual query languages becomes increasingly important. This study is focused on XML-GL, the only graphical query language invented so far. The features of XML-GL and XML-GL, an extended version of XML-GL are summarized. By comparing XML-GL with several XML textual query languages through their data models, examples, and functions, the advantages of XML-GL, and suitable situations to use XML-GL are investigated. It will be shown that XML-GL is a powerful query language and provides a better representation for complex objects and relationships. Therefore, it makes query of normal XML documents more efficient and query of very complex documents possible.