[news.eclipse.technology.equinox] Re: Bundle dependencies

[Henrik Lindberg <henrik.lindberg@xxxxxxxxxxxxxx>]

Maurizio wrote:
> Dear Henrik,
> Thanks very much for your reply.
> I'm not requiring bundles in source format. Only installed bundles, at 
> this moment.
> I understand that there are API to inquiry their dependencies, but I was 
> wondering if I could access their manifest, where the "Require-Bundle" 
> should be explicit mentioned and so I can download or install any other 
> bundle that is required.
>
> To make an example, I started downloading a tutorial for using 
> Server-Side Equinox from javaworld website: 
> com.javaworld.sample.osgi.web.declarative. The manifest indicated 
> explicitly "Require-Bundle: org.eclipse.equinox.http.registry", and so I 
> downloaded such bundle before starting my example. The point is that 
> such bundle seems to require "org.eclipse.equinox.registry", and I 
> didn't know that until I started my declarative bundle.
> In this case, having the possibility to access the manifest for the 
> bundle that I downloaded (org.eclipse.equinox.http.registry) whould have 
> done the job that I was looking for.
>
> Does all this make sense?
> Am I following an incorrect approach?
I think you should take a closer look at p2. It sounds like you really 
want to install everything that is required - and this is exactly what 
p2 does for you. It takes everything you have installed into account, as 
well as everything in known repositories, solves dependencies and 
requirements and executes the installation.

Looking at "required bundle" is not enough, you must also handle package 
imports, and in some cases you may also need to search for fragments in 
order to find a working configuration. Filters and constraints in 
installed features and plugins must also be taken into account. If you 
try this on your own, you will find that it quickly snowballs on you and 
eventually you will end up reimplementing the capabilities in p2.

If all you want to do is view the list of required bundles for things in 
your workspace/IDE, then the Buckminster component view is one way of 
displaying them. The Buckminster view works in earlier Eclipse versions 
as well. (I am sure there are other ways of finding the dependencies, 
but the Buckminster component view is what I usually use for a quick look).

Regards
- henrik