Hello Ancoron,
thanks for your suggestion. We did something similar before switching
to a specified solution to be more flexible concerning different deployment
scenarios and future requirements. The problem with your approach is
that you also need to modify the resource loading mechanism of the
servlet context.
If a static resource, e.g. an image, is requested, the servlet
container usually dispatches this request to a default servlet which
calls the getResource()-method of the ServletContext and then serves
the resource to the client. So the resource
has to be made available to the ServletContext. To get the resource
from a "plugin"-WAB one has to modify the default behavior of
the servlet container. That of course can be done. For example
Jettys ContextHandler provides a method setBaseResource() to
inject a customized implementation of Resource that has access
to other bundles resources via bundle.getEntry().
I still like the idea of loading resources from other bundles META-INF/resources
path and make them available in the WAB by importing them as a package.
This approach is close to the servlet 3.0 spec mechanism which allows
loading resources from jars in WEB-INF/lib. Since imported packages
of other bundles are treated by the WAB like packages of jars in WEB-INF/lib
by a standard WAR this idea seems to be obvious.
I wonder
- if I missed some point that makes the idea not going to work
- or if this approach should be covered by the WAB-Spec.
Best regards,
Andreas
>
> Hello Andreas,
>
> sorry if I just jump in, but what about this:
>
> * a lightweight "core" WAB containing the basics for a web portal
> * "plugin" WABs with a defined structure that provide additional resources as
> well as functionality
>
> Now you have several options to implement this (there is nothing
> comparable inside official specs up to now AFAIK):
>
> 1.) Extender pattern:
>
> With your "core" WAB you also register an Extender that picks up those
> "plugin" bundles and does all the magic for registering stuff by partly using
> official mechanisms/APIs but also allows to do any custom stuff.
>
> 2.) Custom Services:
>
> Let's say you want to provide the following with your new "plugin" bundles:
> * static resources (CSS, JavaScript, HTML, images, ...)
> * functionality (JSF, JSP, Servlets, CDI beans, EJBs, ...)
>
> Now I could imagine to have a custom "PluginService" interface which
> identifies "plugins" which contains methods to get everything you need to
> access.
>
> In the "core" WAB you just listen to those services becoming available or
> going away and register/unregister appropriately.
>
> E.g. if you then need to build up a web navigation menu or the sitemap, you
> would simply iterate over all registered services and retrieve the information
> you need - purely on-demand - or cache at registration time.
> The same would apply to anything else.
>
> The "PluginService" interface, of course, depends on what you actually need
> but can be adopted to almost anything.
>
>
> Although it would be nice to have something like this at hands with
> official APIs you could also have a look if there are frameworks
> available that enable you to describe such things, so that you don't
> have to write everything on your own.
>
> ...just an idea...
>
> Cheers,
>
> Ancoron
>
>
> On 01/17/2012 10:48 AM, Andreas Klotz wrote:
> > Hello Peter,
> >
> > that is what we have. The WAB serves the static content and provides
> > access to the web framework. Static resources belonging to modularized
> > business
> > units (as separate bundles) are attached as fragments to the WAB and so
> > cannot be activated/
> > deactivated independently.
> >
> > We would prefer to deliver the resources with the bundles implementing
> > the controllers of the web GUI. So that we have a full featured
> presentation
> >
> > layer bundle with controller logic and views with its needed static
> > resources.
> >
> > Best regards,
> >
> > Andreas Klotz
> >
> > A WAB with only static content does not suffice?
> >
> > Kind regards,
> >
> > Peter Kriens
> >
> > On 12 jan. 2012, at 09:27, Andreas Klotz wrote:
> >
> >
> >
> > Hi everybody,
> >
> > we have built a modular application platform using OSGi.
> >
> > To us it is important not only to build modules in the
> >
> > service layer but also in the GUI layer.
> >
> > Our GUI is a web application and we decided to deploy
> >
> > it as a WAB. We are using ZK Ria as web application framework.
> >
> > Everything works fine with regard to reference other
> >
> > bundles from our WAB up to the controller layer. But
> >
> > when it comes to serve static resources from the WAB
> >
> > we are not very happy with our solution.
> >
> > We would like to separate the static resources also
> >
> > in bundles analogue to the modularization of the business
> >
> > and controller layer. But WAB does only support loading
> >
> > resources from the WAB itself and its fragment bundles.
> >
> > So for every business module we build a fragment bundle
> >
> > with its appendant resources such as HTML, CSS, JPGs ...
> >
> > But using fragments leads to loosing dynamic since we
> >
> > cannot activate/deactivate the fragments. But we would
> >
> > like to activate/deactivate, install/uninstall modules
> >
> > at run time.
> >
> > Servlet specification 3.0 allows loading of resources
> >
> > from jar files in WEB-INF/lib if they are located
> >
> > in META-INF/resources inside the jar. Since imported
> >
> > packages of the WAB are (nearly) treated like jars in WEB-INF/lib
> >
> > in a servlet container I was wondering if I can import
> >
> > META-INF/resources from another bundle and load resources
> >
> > from it. Of course one has to use a servlet 3.0 conform
> >
> > container.
> >
> > I have not found anything about this topic in the WAB
> >
> > spec. Some experiments with Gemini 2.0 were not successful.
> >
> > I have read that GlassFish supports this approach.
> >
> > Should the WAB spec cover this topic? Or is it up to
> >
> > the implementers such as Gemini or PAX web to deal
> >
> > with it? Or is there another solution for loading
> >
> > static resources from modules?
> >
> > Best regards,
> >
> > Andreas Klotz
> >
> > --
> > phone: +49 (221) 222 896 24
> > fax: +49 (221) 222 896 11
> > email: [email protected] <mailto:[email protected]>
> >
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