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Jadira Usertype

Jadira Usertype. Integrating Hibernate with Joda Time and JSR 310 http://usertype.sourceforge.net/. Background. Hibernate: Object Relational Mapping Framework for Java. At one time a defacto standard, Hibernate is now also the leading implementation of JPA (Java Persistence API)

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Jadira Usertype

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  1. Jadira Usertype Integrating Hibernate with Joda Time and JSR 310 http://usertype.sourceforge.net/

  2. Background • Hibernate: Object Relational Mapping Framework for Java. At one time a defacto standard, Hibernate is now also the leading implementation of JPA (Java Persistence API) • Joda Time: Widely used API for Date and Time. Superior to java.util.Date and Calendar for many reasons… thread safety, immutable, distinguishes Date, Time, DateTime and Time Zones effectively • JSR310: Overhaul of core Java’s date and time APIs based on Joda Time. Scheduled for Java 7

  3. Why Jadira Usertype • JSR310 does not (yet) integrate with JPA so alternative mechanism is required. Hibernate provides APIs for implementing Usertypes or User-Defined Types • Existing contributed user type support for Joda Time has not been updated for some time • JDBC, Hibernate and Joda Time Contrib all (somewhat unexpectedly) modify dates and times when JVM and Database have different timezones – no good at all for correctly storing a Local Date or DateTime with specific zone.

  4. Project Structure JSR 310 support’s module structure is similar but tests utilise Hibernate 3.6 and JPA2

  5. Timeline

  6. Design Problems • Various representations of types available (String, milliseconds since 1970, SQL Date, Timestamp etc) • Representations can be qualified with and without zones and mapped to single or multiple columns • Addressing the JDBC offsetting problem (http://blog.jadira.co.uk/blog/2010/5/1/javasqldate-types-and-the-offsetting-problem.html) • Maintenance and testing • New challenges – supporting Hibernate 3.6

  7. Mapping Columns: Column Mapper • Most behaviour is consolidated into abstract classes that are parameterized by the type they map to…

  8. Mapping Columns: Column Mapper (2) • … yielding lightweight column mapping implementations

  9. Bringing it all together The type that uses this column-mapper to persist a JodaLocalTime to the database is even more lightweight. Uses Super Type Tokens (http://www.artima.com/weblogs/viewpost.jsp?thread=206350)

  10. Bringing it all together (2) Multi-column types use n column mappers Can reuse mappers written for single column mappings For example: OffsetDateTime is stored as an offset and a LocalDateTime to two columns

  11. Quality • PMD, Findbugs, JDepend used for automated metrics capture • Cobertura provides code coverage information… • Unit Tests use DBUnit, embedded H2Database and JPA: Tests verify that the types actually stored in the database are written, stored and read correctly. • JodaTimeContrib unit tests never verified what was stored… the value was offset incorrectly when written and again when read • During testing uncovered and reported some issues in other open source projects: • JSR 310 Public Draft (relating to formatting of sub-seconds in the Period type) • DBUnit (formatting of milliseconds and nanoseconds in Timestamp types)

  12. Hibernate 3.6 Support • Problem: Hibernate 3.6 changed its Type API, but its not synced to Maven central • Solution: Check for presence of Hibernate 3.6 API and use reflection if available; plan to revisit when JBoss start synchronising their releases to Maven Central

  13. Who Uses Jadira Usertype? • Releases 1.0 and 1.1 totalled 100s of downloads; • Since 1.2 distribution is via Maven Central, statistics are not available; • Since April, Joda Time project has recommended Usertype; • Two community reported bugs and fixes received; • Project used by my employer to support business domains in global sales, operations, financing, integration and web channels; • Project supports equivalents to all Joda Time Contrib types providing ease of migration; • Wherever possible Usertype’sJodaTime and JSR 310 modules provide equivalent user types

  14. Questions?

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