Title page for ETD etd-0721101-140132

Document Type thesis

Author Name Kramer, Diane S.

Email Address dkramer at cs.wpi.edu

URN etd-0721101-140132

Title XEM: XML Evolution Management

Degree MS

Department Computer Science

Advisors
Professor Elke A. Rundensteiner, Advisor
Professor Micha Hofri, Department Head
Professor Isabel Cruz, Reader

Keywords
Schema Evolution
XML
Consistency Preservation
Taxonomy of Changes

Date of Presentation/Defense 2000-12-14

Availability unrestricted

Abstract
As information on the World Wide Web continues to proliferate at an
astounding rate, the Extensible Markup Language (XML) has been emerging as
a standard format for data representation on the web. In many application
domains, specific document type definitions (DTDs) are designed to enforce
a semantically agreed-upon structure of the XML documents. In XML
context, these structural definitions serve as schemata. However, both
the data and the structure (schema) of XML documents tend to change over
time for a multitude of reasons, including to correct design errors in the
DTD, to allow expansion of the application scope over time, or to account
for the merging of several businesses into one. Most of the current
software tools that enable the use of XML do not provide explicit support
for such data or schema changes. Using these tools in a changing
environment entails making manual edits to DTDs and XML data and reloading
them from scratch. In this vein, we put forth the first solution
framework, called XML Evolution Manager (XEM), to manage the evolution of
DTDs and XML documents. XEM provides a minimal yet complete taxonomy of
basic change primitives. These primitives, classified as either data or
schema changes, are consistency-preserving. For a data change, they
ensure that the modified XML document conforms to its DTD both in
structure and constraints. For a schema change, they ensure that the new
DTD is well-formed, and all existing XML documents are transformed also to
conform to the modified DTD. We prove both the completeness of our
evolution taxonomy, as well as its consistency-preserving nature. To
verify the feasibility of our XEM approach we have implemented a working
prototype system in Java, using the XML4J parser from IBM and PSE Pro as
our backend storage system. We present an experimental study run on this
system where we compare the relative efficiencies of the primitive
operations in terms of their execution times. We then contrast these
execution times against the time to reload the data, which would be
required in a manual system. Based on the results of these experiments we
conclude that our approach improves upon the previous method of making
manual changes and reloading data from scratch by providing automated
evolution management facilities for DTDs and XML documents.

Files
kramer.pdf

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Document Type	thesis
Author Name	Kramer, Diane S.
Email Address	dkramer at cs.wpi.edu
URN	etd-0721101-140132
Title	XEM: XML Evolution Management
Degree	MS
Department	Computer Science
Advisors	Professor Elke A. Rundensteiner, Advisor Professor Micha Hofri, Department Head Professor Isabel Cruz, Reader
Keywords	Schema Evolution XML Consistency Preservation Taxonomy of Changes
Date of Presentation/Defense	2000-12-14
Availability	unrestricted
Abstract As information on the World Wide Web continues to proliferate at an astounding rate, the Extensible Markup Language (XML) has been emerging as a standard format for data representation on the web. In many application domains, specific document type definitions (DTDs) are designed to enforce a semantically agreed-upon structure of the XML documents. In XML context, these structural definitions serve as schemata. However, both the data and the structure (schema) of XML documents tend to change over time for a multitude of reasons, including to correct design errors in the DTD, to allow expansion of the application scope over time, or to account for the merging of several businesses into one. Most of the current software tools that enable the use of XML do not provide explicit support for such data or schema changes. Using these tools in a changing environment entails making manual edits to DTDs and XML data and reloading them from scratch. In this vein, we put forth the first solution framework, called XML Evolution Manager (XEM), to manage the evolution of DTDs and XML documents. XEM provides a minimal yet complete taxonomy of basic change primitives. These primitives, classified as either data or schema changes, are consistency-preserving. For a data change, they ensure that the modified XML document conforms to its DTD both in structure and constraints. For a schema change, they ensure that the new DTD is well-formed, and all existing XML documents are transformed also to conform to the modified DTD. We prove both the completeness of our evolution taxonomy, as well as its consistency-preserving nature. To verify the feasibility of our XEM approach we have implemented a working prototype system in Java, using the XML4J parser from IBM and PSE Pro as our backend storage system. We present an experimental study run on this system where we compare the relative efficiencies of the primitive operations in terms of their execution times. We then contrast these execution times against the time to reload the data, which would be required in a manual system. Based on the results of these experiments we conclude that our approach improves upon the previous method of making manual changes and reloading data from scratch by providing automated evolution management facilities for DTDs and XML documents.
Files	kramer.pdf