[bv-dev] Configuring method validation

[Gunnar Morling]

Hi all,

As you know we're likely going to exclude getter methods from method
validation by default and provide means of configuring the exact behavior
(e.g. to have getters validated for individual types).

The question is now how this configuration should look like and where it
should be described. I think there is two separate components here:

1) BV which provides the logic/engine for performing method validation
2) Technologies integrating the method validation feature, e.g. CDI, Spring
etc. For CDI, the behavior of this integration is described in the BV spec
(section 10.2 [1]) as per the Java EE conventions. For e.g. Spring, the
behavior would be described in the Spring documentation.

Regarding the configuration of including/excluding getters, one option
would be to define a BV-specific mechanism for the configuration of (e.g. a
global option in validation.xml and/or an annotation like @ValidateOnCall).
This mechanism would have to be queried by the technologies integrating
with method validation.

Alternatively, whether to include/exclude getters could be part of the
configuration of 2). For CDI, this might e.g. happen by adding an attribute
"validateGetters()" to the interceptor binding annotation triggering method
validation, while e.g. Spring users might define an appropriate point cut
expression matching all those methods they want to validate. For CDI we
would again describe the exact means in section 10.2 of the BV spec.

Personally I'd favor the latter approach for the following reasons:

* The configuration of which methods to intercept is IMO a natural
responsibility of integrating technologies
* Integrating technologies already define mechanisms for handling things
like inheritance of metadata (e.g. configuration given on super-types),
resolving conflicts of global vs. local metadata etc. It makes sense to
reuse these mechanisms instead of defining alternative rules in the BV spec.

On the downside, one would be limited to the means of configuration
provided by a particular integrating technology. E.g. I'm not aware of a
way of global configuration options in CDI (we might try to get this
changed, though). I still think this should be addressed in the integrating
technology instead of BV.

Any thoughts?

--Gunnar

[1] http://beanvalidation.org/latest-draft/spec/#d0e9636
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