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Emmanuel Bernard
(3820) JSR-303: From a world of Constraints to Constrain the world
Technical long talk 50 min
Wednesday, 2008-06-25, 15:00 - 15:50, Arena 8
Emmanuel Bernard - JBoss, a division of Red Hat (speaker)
Topics
Abstract
Constraints are at the very core of our data, they help increase quality and
relevance. Validating the data as often as possible is thus a good step towards
the quality road.
In traditional Java applications, validation are applied at different levels and
different layers, typically:
- the database layer (table / column constraints)
- the ORM layer
- the service layer
- the presentation layer
- the client side layer
Unfortunately, this leads to constraint declaration duplications for each layer
and increases the risk of inconsistencies.
This presentation will describe how JSR-303: Bean Validation addresses this
problem for the Java platform. The attendees will be described the three main
components of the solution as well as when and how this specification will fit
into the Java SE and EE ecosystem.
How to express a constraint
Declaring constraints should be done with no duplication, and be as close as
possible to the data structure: our objects. This presentation will show how
declaring a constraint is as simple as putting an annotation on a field or a
property and how to validate an object graph. Some more advanced topic will be
covered too such as:
- custom constraint definition and implementation through the JSR-303 extension
mechanism,
- constraints grouping to declare use case specific constraints,
- short circuit i.e. the ability to stop a validation process when a given
constraint fails.
How to validate an object
JSR-303 provides a unified and standard API to apply the object validation
routine whether it be by a JSR (like Java Persistence 2 and Java Server Faces),
a framework or an application. This presentation will cover this API as well as
the information provided when one or more failure happen. The customization and
internationalization of the constraint failure messages will be described as
well.
Integrating beyond Java
Beyond object instance validation, the presentation will cover JSR-303's ability
to query and access the constraint metadata repository. The attendee will see
how such informations about the constraints will be reused by frameworks
interacting with the Object world boundaries such as Java Persistence 2 or Java
Server Faces 2 components.
No prerequisite knowledge is necessary aside Java 5.
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