7 Nov
2012
7 Nov
'12
5:28 p.m.
I just looked at some documentation and indeed there is injection based servlet
registration.
I'm all for using existing standards but there seem to be some issues with this
implementation.
Until we stop supporting servlets 2.x (tomcat < 7.0) we would need an adapter to
support this functionality.
Servlets3 supports dynamically loading servlets (ServletContext#add[Servlet|Filter]) but
doesn't seem
to have a standard way to remove them which would break servlets in extensions.
Servlets are loaded at start time by scanning over all class files in the application,
I'm not sure how this will be for performance.
Unless we used special code in the ECM, servlets would not be able to use dependency
injection without explicitly getting the CM itself.
Given these limitations I think that for now it makes the most sense to break from the
standard and roll our own servlet which redirects to a servlet which is registered as a
@Component.
Thanks,
Caleb
On 11/07/2012 08:46 AM, Thomas Mortagne wrote:
Isn't the possibility to inject servlet without
having to modiify web.xml
part of Servlet 3 ?
On Wed, Nov 7, 2012 at 2:41 PM, Caleb James DeLisle <
calebdelisle(a)lavabit.com> wrote:
Hi,
I'd like to register servlets in the component manager and have them
called by their hint.
The oldcore struts servlet would be @Named("bin") and the rest servlet
would be @Named("rest")
Reasons to want to do this:
* There are things which are currently impossible without a servlet,
things like REST, GWT and WebDav.
* If somebody has servlet code and they want to make it run in XWiki, this
is a real answer for them whereas "rewrite your app using XWiki actions"
isn't.
* Even if we had an Actions system which made it *possible* to implement
REST, GWT, and WebDav entry points, we would have to rewrite the universe
since all external libraries use Servlet.
* Web.xml is an eyesore, it's full of content which is the concern only of
a particular module, this could (mostly) be fixed by using injected
servlets.
The big reason not to like it is because it could undermine the proposal
for Actions.
The JIRA issue for actions http://jira.xwiki.org/browse/XWIKI-4713 was
opened on January 1 of 2010.
It is stalled because nobody really knows how to make an abstraction which
represents Servlets or Portlets without any lost features.
If we make it easier for servlets to be used, we might begin down a
slippery slope toward everything being done using servlets and then we lose
portlet compatibility.
But the alternative as I see it is to block progress in this direction and
hope that somebody steps up to implement Actions which are fully compatible
with portlets and servlets.
WDYT?
Are there reasons not to do this which I missed?
Caleb
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