An Efficient Compressor for XML
 
 
 
 Abstract:
 
 XML is becoming an increasingly popular standard for representing and
storing 
 documents and for transporting data over the Internet. The amount of
data 
 available in XML is growing rapidly and efficient transport and storage 
 techniques are necessary. One such technique is compression.
Conventional 
 compressors - such as Lempel-Ziv, or Huffman encoding - achieve
reasonable 
 compression. However they do not consider the specific syntax and 
 semantics of XML and thus miss several opportunities for compression.
  
 In this talk, we will describe a special purpose compressor for XML, 
 called XMLzip, that improves over general purpose ones. The main 
 component of XMLzip is a clustering technique that groups data elements 
 together before applying conventional data compression to them.
Depending on 
 the type of XML data to be compressed, the user can choose between
default 
 clustering techniques or can define own clustering strategies using
regular 
 expressions. Furthermore, XMLzip allows the user to add domain-specific 
 compressors for complex text structures, such as URLs or dates. 
 Consequently, further improvement of the compression rate can be
obtained.