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From Matt Benson <>
Subject Re: Bean Validation for GWT
Date Tue, 20 Jul 2010 19:52:25 GMT

On Jul 20, 2010, at 9:39 AM, Nick Chalko wrote:

> On Tue, Jul 20, 2010 at 6:44 AM, Matt Benson <> wrote:
>> Hi Nick--so, the GWT alternative to reflection would be some form of
>> javascript inspection, or do they provide an API over that?  I never got
>> around to giving GWT a try, so I am completely unfamiliar with how it works
>> beyond a vague awareness that everything compiles to javascript (if that's
>> even correct).  It sounds like you're saying the entire app, including
>> bytecodes from third-party libraries, is ported and it all runs client-side,
>> with reflection being a (the?) java API that is conspicuously unavailable.
>>  My initial reaction to this is that it this would seem likely to cause
>> problems working with many Java libraries.  To go beyond Bean Validation
>> here, it sounds like a reflection analogue of slf4j might be in order,
>> whereby a secondary "reflection" API is defined, with implementation jars
>> provided at runtime.  Applications/libraries wanting to provide support for
>> environments where java.reflect reflection is unavailable, but some
>> alternative exists, could then code to the redefined API.  It happens that I
>> have contributed for some years to a library that includes such an API, and
>> have given thought over the years to incubating an overhaul of it at Apache
>> (targeted for Commons).  If I've not guessed badly on any of the
>> fundamentals, this would seem a reasonable direction to take.
>> -Matt
> Matt,
> GWT use Differed binding
> (
> My main question was, how isolated is the code that need reflection.
> My assumption is should only be needed in the code that actually
> validates an object graph.

Not really.  A JSR303 validator would also need to hunt for annotations in a given class,
as well as using reflection-based tricks to generate proxies for XML-declared validation constraints.
 All in all it would seem that a  unified interface with various implementations would be
the appropriate mechanism to get interoperability between GWT and libraries that typically
use reflection in Java runtime environments.

> I will down load and start poking around in the code.
> My second question is,  Is there interest a bval-gwt subproject?

I didn't want to speak for the community, but given Donald's input, I would agree:  the more
the merrier.


> R,
> nick

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