Template-Based Wrappers in the TSIMMIS System Joachim Hammer Hector Garcia-Molina Svetlozer Nestorov Ramana Yerneni Marcus Breunig Vasilia Vassalos SIGMOD97

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

Wrapper Architecture

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

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

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

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 Parser

Template Rule “Parameterized MSL query” Matcher

Template Rule (Cont.) Action: // $$ = “select * from book Where author = ” $X “Jones” “Parameterized MSL query” “Parameterized SQL query”

Native SQL Query select * from book where author = “Jones”

Postprocessing B: -B: }> AND lt(Y, 1984) select * from book where author = “Jones” Engine

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

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