HEPTOX 1 : Marrying XML and Heterogeneity in Your P2P Databases Angela Bonifati (Icar CNR, Italy), Elaine Q.Chang, Laks V.S.Lakshmanan, Terence Ho, Rachel Pottinger, Shuan Wang and Ting Wang (UBC, Canada) 1 HEPTOX stands for “Heterogeneous Peers Talk!”

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Motivations for Marrying XML and Heterogeneity in P2P Databases Peers contain similar and related XML data Each peer wants to keep its own schema and yet needs to be mapped to others’ schemas [cfr. –autonomy, flexibility are important in P2P –a global mediated schema is unfeasible Queries are still formulated against one (e.g. local) schema –Need to transparently cross the different schemas Previous work [Clio, Hyperion, Piazza] could only handle limited heterogeneity

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 A P2P Network of Heterogeneous Hospitals Peer 1 Peer 2 DTD 1 DTD 2 DTD n Peer n.... Event... Date Problem Admission... CoronaryPulmonary... ID InsName...

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Heterogeneity and XML data: an example Consider a P2P network of hospitals and an unfortunate patient moving among them: –Option#1: the patient carries his/her own files and query translation is done manually It is error-prone, and unfeasible with several moves and with frequent joining/leaving of peers –Option#2: the hospital db admin manually writes the mappings It is not that easy to find a person who knows the rule machinery that well!

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Heterogeneity and XML data: an example –Option#3: the hospital db admin provides informal arrows/boxes correspondences w.r.t. a set of acquaintances: Users/applications do not know the underlying mappings machinery and can keep it simple A peer’s entering the network is a lightweight operation

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 What do input mappings look like? What do input mappings look like?

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Mappings in hospital schemas XML mappings in HePToX are specified informally by arrows and boxes which encode: –Data/Metadata correspondences –Structure correspondences –The informal mappings are translated to Datalog-like mapping rules. Data/Metadata conflicts are not dealt with in previous works: Data/Metadata conflicts are not dealt with in previous works: –Addressed in HepToX Event DateProblem Pulmonary Coronary Admission

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Demo scenarios Doctors: track patients Patients: access their data Insurance Companies: define the policy for a set of patients Etc.

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 HepToX Contributions GUI for specifying correspondences (arrows/boxes) Datalog-like mapping language for working with complex XML trees Rule Inference algorithm for producing the Datalog-like mapping rules Query Translation algorithm based on those mappings that works for a significant subset of XQuery (TPs with joins) Our “Data Exchange” semantics, which differs from GAV and LAV mappings

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Demo Screenshots 1/2 Schema Mappings By Boxes/Arrows and Corresponding Datalog-like Rules

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 Demo Screenshots 2/2 Details of Query Translation Algorithm (for each pair )

See our demo! This afternoon 14:00-15:30 & Thursday 14:00-15:30 On HEPTOX implementation The demo shows the following features: –Draw mappings and show the generation of rules –Show the query translation algorithm at work –Show a real network emulation with Emulab HEPTOX is implemented in Java: –Uses QizX [QizX] as the underlying XQuery engine –FreePastry as the underlying P2P protocol –Emulab as the real network emulation environment –It consists of ~10,000 lines of code

Come visit our demo booth: This afternoon 14:00-15:30 & Thursday 14:00-15:30