Engine GroupNamiruddin Ahmed

Ali Kamil

2

XMLApe

XMLApe Research Group• Involved in research on a number of projects that

are related to XML and inspired by databases Engine Group

• Develop DBMS that ties XMLApe GUI to multiple XMLApe Data Sources

• Split query involving multiple sources into multiple queries on single sources

• Merge multiple result sets and return to XMLApe GUI

3

XMLApe Architecture

4

Splitting a Query

<?xml version="1.0" encoding="UTF-8"?><query xmlns="http://199.77.128.59:8080/query""> <source> <location>http://199.77.128.59:8080/flights/flights.xsd</location> <alias>Flight_1</alias> </source> <source> <location>http://199.77.128.59:8080/flights/flights.xsd</location> <alias>Flight_2</alias> </source> <source> <location>http://199.77.128.59:8080/rentals/rentals.xsd</location> <alias>CarRental_1</alias> </source> <select> <schemaRef> <alias>Flight_1</alias> <field>flights/flightflightFrom</field> </schemaRef> <value>Detroit</value> </select>

<join> <schemaRef> <alias>Flight_1</alias> <field>/flights/flight/flightTo</field> </schemaRef> <schemaRef> <alias>Flight_2</alias> <field>/flights/flight/flightFrom</field> </schemaRef> <schemaRef> <alias>CarRental_1</alias> <field>/flights/flight/rentalFrom</field> </schemaRef> <schemaRef> <alias>CarRental_1</alias> <field>/rentals/rental/rentalTo</field> </schemaRef> </join></query>

SubQuery 1

SubQuery 2

SubQuery 3

Figure: Query Splitter. Splitting a multi-source distributed query into single-source query documents.

5

Resulting Queries

Figure: Query Splitter. Splitting a multi-source distributed query into single-source query documents.

<?xml version="1.0" encoding="UTF-8"?><query xmlns="http://199.77.128.59:8080/query"> <source> <location>http://199.77.128.59:8080/flights/flights.xsd</location> <alias>Flight_1</alias> </source> <select> <schemaRef> <alias>Flight_1</alias> <field>/flights/flight/flightFrom</field> </schemaRef> <value>Detroit</value> </select></query>

SubQuery 1

<?xml version="1.0" encoding="UTF-8"?><query xmlns=“http://199.77.128.59:8080/query”> <source> <location>http://199.77.128.59:8080/flights/flights.xsd</location> <alias>Flight_2</alias> </source></query>

SubQuery 2

<?xml version="1.0" encoding="UTF-8"?><query xmlns="http://199.77.128.59:8080/query"> <source> <location>http://199.77.128.59:8080/rentals/rentals.xsd</location> <alias>CarRental_1</alias> </source> <join> <schemaRef> <alias>CarRental_1</alias> <field>/rentals/rental/rentalFrom</field> </schemaRef> <schemaRef> <alias>CarRental_1</alias> <field>/rentals/rental/rentalTo</field> </schemaRef> </join> </query>

SubQuery 3

6

Future Work

Unify sub queries on the same data source• Merge sub queries using operations like self-joins to be

performed natively on data source

Projections and non-equi joins• Change Schema Melder to publish result schema for the

user interface depending on the projections in the query document

Support result reorganization Making engine page from disk

• Reduce memory drain when dealing with larger result sets