Merging Source Query Interfaces on Web Databases

1. Merging Source Query Interfaces on Web Databases Eduard C. Dragut(speaker) Wensheng Wu Prasad Sistla Clement Yu Weiyi Meng University of Illinois at Chicago University of Illinois at Urbana-Champaign University of Illinois at Chicago University of Illinois at Chicago SUNY at Binghamton ICDE 2006, Atlanta, USA

2. orbitz.com delta.com A Motivating Scenario: • Looking for a ticket • Chicago – Atlanta, April 3rd – April 9th aa.com • A user looking for the “best” price for a ticket: • Has to explore multiple sources • It is tedious, frustrating and time-consuming E. Dragut et al - Merging Source Query Interfaces on Web Databases

3. Formulate the query The goal • Provide a unified way to query multiple sources in the same domain The Web Unified query interface Airfare.com priceline.com united.com delta.com nwa.com E. Dragut et al - Merging Source Query Interfaces on Web Databases

4. Auto Car Rental Books Extract query interfaces Cluster query interfaces Match query interfaces He05, Zhang04 B.He03, Dhamankar04, Doan02, Madvan05, Wu04 Airfare Peng04 Various formats e.g. ASCII files Merge Query Interfaces H.He03 • The topic of this presentation Overview Integrating Query Interfaces (Deep) Web E. Dragut et al - Merging Source Query Interfaces on Web Databases

5. Merge Algorithm • The input • A set of query interfaces in the same domain • E.g. Airline domain: Delta, AA, NWA, Orbitz, Travelocity • Each query interface is represented hierarchically [Wu04] • Anda mapping, globally characterizing the semantic correspondences between the fields in the query interfaces. • Organized in clusters (e.g. [Wu04 et al, B.He03 et al]) vacations.net E. Dragut et al - Merging Source Query Interfaces on Web Databases

6. An Example • Three fragments of query interfaces represented hierarchically • The mapping between them, i.e. the set of clusters E. Dragut et al - Merging Source Query Interfaces on Web Databases

7. Merge Algorithm • The output • A unified query interface that • consists of all the fields of individual interfaces, i.e. it has afield for each of the clusters in the mapping definition • preserves all the constraints enforced by the interfaces being merged • The constraints to be satisfied by the global interface are: • the grouping constraints (to be described) and • the ancestor-descendant relationships among the elements within individual interfaces. E. Dragut et al - Merging Source Query Interfaces on Web Databases

8. Grouping • Within a domain of discourse (e.g. Airfare) we observe: • A spatial locality property among the fields of query interfaces • Designers tend to place related fields close to each other • Hence, in the integrated interface these fields should be placed in adjacent positions, too E. Dragut et al - Merging Source Query Interfaces on Web Databases

9. Grouping Problem • The goal (requirement) • Groups of fields that occur together in the source query interfaces to appear together in the integrated interface • The actual order of elements is immaterial • The problem • Find a partition over the set of fields of a given domain characterizing the way fields are grouped in the integrated interface. E. Dragut et al - Merging Source Query Interfaces on Web Databases

10. Capture Grouping Constrains • Introduce the notion of potential groups • Informally, it is a maximal set of adjacent sibling leaves whose parent is not the root • Capture the way fields are organized within source query interfaces • Underline designer’s perspective that these fields should be together so that users can easily understand what is required and fill in the desired information with ease. • Example The set of all potential groups induced by query interface Travel E. Dragut et al - Merging Source Query Interfaces on Web Databases

11. Constructing Groups • Use these structural information collected from multiple source interfaces to infer the way fields are organized in the integrated interface • Introduce the notion of a group of fields • Informally, it is a sequence of fields that preserves the adjacency constraints within related potential groups • Two potential groups are related if their intersection is nonempty. • A group represents the desired organization of the fields in an integrated interface • An example: • Set of related potential groups: • {Depday, DepMonth, DepTime}, {Departure month, Departure day, Departure Year}, {depDay, depMonth} • The resulted group: • [DepTime, Departure day, Departure month, Departure Year] E. Dragut et al - Merging Source Query Interfaces on Web Databases

12. Grouping Problem as C1P • The grouping problem can be cast into the Consecutive Ones Property (C1P) problem [Booth76 et al, Fulkerson65 at al]. • For an universal set U and a subset, B, of the power set of U we want a permutation пof the elements of U such that all the elements in each set in B appear as a consecutive sequence in п. • In our grouping problem • Potential groups correspond to the set B • U is the union of the fields in the potential groups • П is the desired permutation of the fields • Several algorithms to obtain the groups in the integrated schema • E.g. PQ-tree algorithm [Meidanis98 et al] • Used in our implementation E. Dragut et al - Merging Source Query Interfaces on Web Databases

13. Grouping Problem as C1P • An example of applying the PQ-tree algorithm • Set of related potential groups: • B = {{c_DepDay, c_DepMonth, c_DepTime}, {c_DepMonth, c_DepDay, c_DepYear}, {c_DepDay, c_DepMonth}} • U = {c_DepDay, c_DepMonth, c_DepYear, c_DepTime} Frontier gives the group • A permutation satisfying all related potential groups cannot always be derived • Minimize the number of violations E. Dragut et al - Merging Source Query Interfaces on Web Databases

14. Constructing Groups • On the running example • The set of all groups • [c_DepCity, c_DestCity] • [c_DepTime, c_DepDay, c_DepMonth, c_DepYear] • [c_Seniors, c_Adults, c_Children, c_Infants] E. Dragut et al - Merging Source Query Interfaces on Web Databases

15. Constructing Groups • On the running example • The set of all groups • [c_DepCity, c_DestCity] • [c_DepTime, c_DepDay, c_DepMonth, c_DepYear] • [c_Seniors, c_Adults, c_Children, c_Infants] They were not considered (children of the root) E. Dragut et al - Merging Source Query Interfaces on Web Databases

16. Pairwise merge • For a set of query interfaces: • Iteratively merge two at a time • Traversing the schema trees bottom-up • Placing of group elements • Preserving ancestor-descendant relationships in the source schemas • On the running example • First iteration E. Dragut et al - Merging Source Query Interfaces on Web Databases

17. Pairwise merge • Second iteration • Note, the fields are naturally placed in the merged interface E. Dragut et al - Merging Source Query Interfaces on Web Databases

18. Experiment • Setup • Five real world domain: • Mapping consists of clusters [Wu04 et al] E. Dragut et al - Merging Source Query Interfaces on Web Databases

19. Experiment • The characteristics of the integrated interfaces. • All group constraints are satisfied with the exception of two potential groups in the airline domain • [Seniors, Adults, Children, Infants] and [Airline, Class, NonStop]. E. Dragut et al - Merging Source Query Interfaces on Web Databases

20. Example Integrated Interfaces • Airfare domain integrated interface • Note that fields are placed naturally E. Dragut et al - Merging Source Query Interfaces on Web Databases

21. Example Integrated Interfaces • Auto domain integrated interface • Note that fields are placed naturally E. Dragut et al - Merging Source Query Interfaces on Web Databases

22. End • Please visit the project web site • http://www.cs.uic.edu/~edragut/QIProject.html Thank you for your time and patience! E. Dragut et al - Merging Source Query Interfaces on Web Databases