Computing graphical queries over XML data

Sara Comai, Ernesto Damiani, Piero Fraternali

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


The rapid evolution of XML from a mere data exchange format to a universal syntax for encoding domain-specific information raises the need for new query languages specifically conceived to address the characteristics of XML. Such languages should be able not only to extract information from XML documents, but also to apply powerful transformation and restructuring operators, based on a well-defined semantics. Moreover, XML queries should be natural to write and understand, as nontechnical persons also are expected to access the large XML information bases supporting their businesses. This article describes XML-GL, a graphical query language for XML data. XML-GL's uniqueness is in the definition of a graph-based syntax to express a wide variety of XML queries, ranging from simple selections to expressive data transformations involving grouping, aggregation, and arithmetic calculations. XML-GL has an operational semantics based on the notion of graph matching, which serves as a guideline both for the implementation of native processors, and for the adoption of XML-GL as a front-end to any of the XML query languages that are presently under discussion as the standard paradigm for querying XML data.

Original languageBritish English
Pages (from-to)371-430
Number of pages60
JournalACM Transactions on Information Systems
Issue number4
StatePublished - Oct 2001


  • Document restructuring
  • Graphical query languages
  • II.2.3 [Information Systems]: Languages - XML documents
  • II.3.3 [Information Systems]: Information Storage and Retrieval
  • Languages
  • Semantics


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