1. Presenting Statistical Data Using XML Office for National Statistics, United Kingdom Rob Hawkins, Application Development

2. Presenting Statistical Data Using XML Supporting paper for MSIS 2005 Reference: CES/AC.71/2005/23 Mission Requirements and Examples Component Design The Future Questions at the end please !

3. Mission Develop a Java component, which queries a large relational database (300 million statistical values and supporting metadata) produces a variety of statistical outputs enables a range of user interactions with the outputs can be integrated into any Java-based web application performs and scales well on busy public-facing web-sites is flexible and extensible

4. Mission Key customer: UK Neighbourhood Statistics Programme (NeSS) Web-site to provide better information for neighbourhood renewal Also, build the component so that it can be re-used for other web projects

5. Requirements and Examples HTML tables

6. Requirements and Examples Charts

7. Requirements and Examples Thematic maps

8. Requirements and Examples Print-friendly examples

9. Requirements and Examples Metadata Linking Requirement to access contextual metadata from items in tables, charts, and maps

10. Requirements and Examples Neighbourhood Profiles (a report per area, with multiple outputs on same page)

11. Component Design Simple API hides internal complexity Internal re-design can be carried out without affecting the client-code Written as a “framework” for re-use Stateless and not dependent on web-site that uses it Design is suited to being encapsulated by a Web Service

12. Use of XML and XSLT Instead of building the output directly from relational database queries, we first create the results as XML We then use XSLT transformations to convert the XML into the required form (HTML, CSV, SVG, etc) Re-usability of the solution is improved by use of a common, multi-dimensional XML Schema As long as XML conforming to the schema can be produced, any data source can be used, e.g. legacy sources The entire process is dynamic, carried out when the web- site user clicks “go” – querying the database, building the XML, running the XSLT transformation This is all run on the server – there is no transformation taking place on the client

13. Simplified design diagram HTML, XML XML Transformer XML & XSLT XRender Service Layer Data Request (What I want) Presentation Request (How I want it) Chart (URL) HTML table HTML,SVG, CSV Client code CSV, etc. SVG Map GIS Service PopChart ArcXML XML HTML Process Layer Data and Metadata Presentation Rules (XSLT) Common XML Schema Data and XML Cache XML XSLT

14. Re-usable framework Business Data Sources & Stored Procedures Business Data Access Objects turn database queries into XML Generic Objects Model and Build the Common XML Schema Generic Process objects Coordinate the Transformations Business Process Objects build the client response Business Configuration XML used to tailor the output Generic XSLT chains Business XSLT chains Business API layer Environmental configuration XML Business Cascading Style Sheets Business JavaScript Generic Utility Objects e.g. for Caching, automating the transformations, building charts “Plug-and-Play” Design “Business” = Business-domain specific code and configuration – e.g. for NeSS requirements

15. Performance and Scalability High-volume public web-site – peaks at hundreds of concurrent user requests Requirement to render most output within a couple of seconds as a worst-case average Techniques used: –Oracle index tuning and query hints –Memory caches to minimise database access. –XSLTC (Pre-compiles XSLT scripts) –Balance and optimise the work done by Java and by XSLT

16. The future Further ongoing enhancements for NeSS Re-use component on UK “National Statistics Online” web- sites Share ideas (and code?) with other National Statistics Institutes ?

17. End of presentation Any questions ?