XML Data Transformation

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XML Data Transformation Integration
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Overview

• Objective restructuring integration of XML
  files
• Schema matching process assumed
• Aims
• XML-specific solution
• Avoid loss of data due to structural
  incompatibilities
• Automation

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Problems

• Same information can be represented in many
  different ways
• Ancestor descendant ?? different branches
• Elements attributes not clearly distinguished
  in XML model

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XML DataSource Schema (1/2)

• Basic characteristics
• Structure-only representation
• XML format ? ease of traversal manipulation
• Automatically derived from an XML file
• XMLDSS from other schema types (DTD, XML Schema)

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XML DataSource Schema (2/2)
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Restructuring Scenario

• Schema matching phase
• Schema transformation phase
• id phase
• Target schema materialisation

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Restructuring Algorithm

• Growing phase traverse T and issue an add/extend
  transformation for every construct that does not
  exist in S
• Shrinking phase traverse S and issue an
  delete/contract transformation for every
  construct that does not exist in T

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Example 1

• Insert element
• extend(ltCgt,Void,Any)
• extend(ltr,C,2gt,Void,Any)
• extend(ltC,PCData,1gt,
• Void,Any)
• Remove element
• contract(ltC,PCData,1gt,
• Void,Any)
• contract(ltr,C,2gt,Void,Any)
• contract(ltCgt,Void,Any)

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Example 2

• Move
• add(ltroot,B,1gt,q3)
• add(ltB,A,1gt,
• b,aa,b?ltA,Bgt)
• delete(ltA,B,1gt)
• a,bb,a?ltB,Agt)
• Complete
• add(ltBgt, ltBgtq1)
• add(ltA,B,1gt, ltA,Bgtq2)
• delete(ltA,B,1gt, ltA,Bgt)
• delete(ltBgt, ltBgt)
• rename(ltBgt, ltBgt)

Schemas
Data
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Example 3

• Element-to-attribute transformation
• add(ltA, Bgt,q)
• delete(ltA,B,1gt,q)
• delete(ltB,PCData,1gt,q)
• delete(ltBgt,q)
• Attribute-to-elementtransformation
• add(ltBgt,q)
• add(ltA,B,1gt,q)
• add(ltB,PCData,1gt,q)
• delete(ltA,Bgt,q)

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Integration Scenario

• Schema matching phase
• Schema transformation phase
• id phase
• Global schema materialisation

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Schema Integration Type I
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Schema Integration Type II

• Type I integration performs two tasks at once
• schema integration
• schema improvement
• Type II simply integrates
• Schema improvement at a later stage

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Querying

• Wrappers
• DOM (XPath)
• SAX
• Under development
• XML databases
• Native XML databases

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Materialisation

• Strategy
• Materialise root and its attributes
• Consider all edges (ep,ec) in a depth-first way
• Materialise ec and its attributes

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Evaluation

• BIOMAP
• Integration of biological data sources
• Relational databases, XML documents, XML
  databases

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Ongoing Work - Research

• Modify restructuring integration and algorithms
  to accept input
• AutoMeds schema matching tool
• Ontologies (RDFS/OWL)

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Future Work

• Extend XMLDSS
• Schema evolution
• Targeted rematerialisation of GS
• Streaming integration/materialisation