Template-Based Wrappers in the TSIMMIS System

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Template-Based Wrappers in the TSIMMIS System

• Joachim Hammer
• Hector Garcia-Molina
• Svetlozer Nestorov
• Ramana Yerneni
• Marcus Breunig
• Vasilia Vassalos

SIGMOD97
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Wrapper

• Problem A lot of effort required to develop and
  write a wrapper
• Solution
• Wrapper implementation toolkit
• Template-based translation technology

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Wrapper Architecture
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OEM

• Every object has an OID, type, label, and value.
• OEM Object Example (omitting the type and OID)

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MSL

• A rule-based language
• MSL rule
• Head
• Tail

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Example

• Assumption
• A relational database contains bibliographic
  information about books and papers
• The database accepts SQL queries
• The wrapper accepts MSL queries
• Parser
• Matcher
• Engine

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MSL Query
Find all publications labeled book which have
subobjects year and author, and for which the
author field has value Jones and the year field
value is less than 1984.
Parser
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Template Rule
Parameterized MSL query
Matcher
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Template Rule (Cont.)
Parameterized MSL query
Action // select from book Where author
X
Parameterized SQL query
Jones
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Native SQL Query
select from book where author Jones
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Postprocessing
B -B ltbook ltyear Ygtgt AND lt(Y, 1984)
Engine
select from book where author Jones
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Demo

• A university-owned legacy system called FOLIO,
  which is accessible through an interactive
  front-end (called INSPEC)
• A Sybase relational DBMS which is accessible
  through SQL
• A collection of UNIX files which is accessible
  through a Perl script file
• A World-Wide Web source which is accessible
  through a WWW extraction utility

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Conclusion

• Wrappers hide all source specific details from
  the application/end user
• Quickly enhance the query capabilities of a
  wrapper
• Change the resulting answer structures
• MOBIE