Re: [xwiki-devs] [PROPOSAL] Allow servlets to be registered with the ComponentManager.

Hi Caleb, On Nov 7, 2012, at 2:41 PM, Caleb James DeLisle <calebdelisle(a)lavabit.com> wrote: REST and WebDAV for example can be done without needing a new Servlet by using a tighter integration. I don't know enough about GWT to know if it's possible or not but I guess it is too (at the expense or writing a bit more code since you'll need to call some GWT APIs to do serialization/deserialization). Indeed, and we've been waiting for Servlet 3.0 so far. Last time we checked it was still to early to use Servlet 3.0 (see threads on markmail). Indeed and Servlet 3.0 seems a good answer. Now you're right that Servlet 3.0 doesn't support dynamic unregistration of Servlets (only addition) so if we want to bring in servlets in an extension that's not possible. This is also why I prefer the tight integration approach which doesn't have this problem (i.e. do away with Servlets). I started the Action module and I didn't finish simply for lack of time. There's no blocker. I wanted to finish the URL module before working on it again but I didn't get the time to finish it either. My take on Servlets within XWiki in general: * We should not use Servlets when there are other ways of integrating external tools. When possible a tighter integration should be chosen since it allows to use our development practices with component injection and makes it simpler for deployment (removes the burden to have to modify web.xml). * Another reason for having only 1 entry point (or a minimal number of entry points) is that defining more entry points is a pain for maintenance as we've been experiencing over and over for the past years. The problem is that a new entry point means that you need to duplicate all initialization of XWiki Context/Execution context for each incoming request and this is tricky and all our entry points were doing it wrongly at some point (case in point, Andreas just fixed 2 bugs yesterday where some threads were not cloning the xwiki context). Yes we should be able to factor all this init in a common place (which we almost have but in practice it doesn't seem to really happen for some reason). Regarding your proposal: * It seems a bit of hack to call a Servlet by doing a new on it. It goes against the concept of Servlets actually which is supposed to be handled by the Container. More generally what you propose is what OSGi is doing too: - http://www.peterfriese.de/osgi-servlets-a-happy-marriage/ - http://felix.apache.org/site/apache-felix-http-service.html The real questions for me are: 1/ Could you explain what's your actual use case so that we could discuss alternatives, if any? 2/ Do we really want to support adding/removing servlets at runtime? If the answer to 2/ is yes then your proposal is the only one I could see working indeed. Regarding @Named("bin"), I think it would be good to review all our existing URLs and verify it'll work. For example ATM we also have "skin" and "skins" AFAIR which are currently handled by the same Servlet as "bin" and thus we'd need to find a solution for this too + we need to review the GWT, WebDAV URLs too. It would also be nice for the xwiki URL module to be able to handle different URL formats based on the "servlet/service" instead of the scheme being fixed for all which is currently the case. Thanks -Vincent