Eclipse Modeling Framework (EMF) port to GWT

[Ed Merks]

I'm busy refining EMF's support for GWT:

http://wiki.eclipse.org/EMF/New_and_Noteworthy/Helios#Support_for_Google_Web_Toolkit_.28GWT.29

One of the problems I have is that I need to support converting date
instances to and from a string representation, in particular, one that
conforms to XMLSchema's dataTime format. I have that working nicely in
regular Java with SimpleDateFormat, but that's not supported by GWT.
So I ported it to use DateTimeFormat. That's working nicely too. But
now, after more testing, I realize that DateTimeFormat doesn't work on
the server, because it depends on locale stuff, which the server
doesn't support. That's unfortunate because the format I'm producing
isn't actually locale specific. In any case, what I really want is a
single library that works for both the client and the server. I get
the sense that I need two different implementations, a default one
that's good on the client, and a different one that works on the
server.

There are many tricks I could play if this were all pure Java. I've
done similar things to make EMF work both within Eclipse and as stand
alone jars. But I'm all out of ideas for how to make this work with
GWT and I was hoping someone would have a good suggestion. As an
example of an approach I might use is:

if (GWT.isClient())
{
// Use DateTimeFormat
}
else
{
// Use SimpleDateFormat
}

That doesn't work of course because the GWT compiler will complain
about SimpleDateFormat even though that code path will never be taken
on the client. I thought the GWT compiler might prune out the
unreachable branch. If I could move the "else" part to a different
method and mark that whole method as to-be-ignored by the GWT
compiler, that would make me happy too, but I didn't find any
annotation that would direct the GWT compiler to ignore something.

Another approach I could take is to inject different implementations
depending on where I'm running, client or server. That's certainly
feasible, but where to put the initialization code? To make it
easier, I could have a default implementation that works on the client
and then in the case of running on the server, initialization code
would inject one that works for the server. I could a call to such a
hook in every XyzServiceImpl, full Java is allowed there, but that's
easy to forget and kind of annoying. How could I ensure that such
server-specific, won't-compile-with-GWT, initialization code is
invoked once for the server?

Any other ideas for how I could maintain a single source/library/
project that adaptively works for both the client and the server based
on different implementation classes?

[dolc...@gmail.com]

You can provide a dummy supersource implementation of
SimpleDateTimeFormat so that it would compile.

On Jun 2, 12:12 pm, Ed Merks <ed.me...@gmail.com> wrote:
> I'm busy refining EMF's support for GWT:
>

>  http://wiki.eclipse.org/EMF/New_and_Noteworthy/Helios#Support_for_Goo...