[Opensim-dev] Module/Plugin Loading

Wed Jun 25 20:09:23 UTC 2008

I've been thinking about what it would take to implement a crude wind model
in opensim, and this thread appears to be along the lines of some of my
thoughts. I've done some CFD visualization work several years ago, but I am
by no means an expert and as such I think I would rather concentrate on
developing the hooks and providing a basic model that can be unplugged and
replaced with other models that would be better suited for more demanding
applications. Such a model may need access to simulation variables like time
of day, sun position, the object meshes used by the physics engine and their
layout in 3D space, weather conditions of neighboring regions, and probably
others. It may need to send weather data to agents in the simulation area,
and expose data to the scripting engine to support functions such as
llWind(). It would also need to be informed of changes in the region such as
adding prims or terrain modifications.

As a relatively new contributor, I'm not really familiar with the benefits
or drawbacks of the various means of plugging in code with these
requirements, and it appears that many of these issues are being brought up
here which is what prompted me it add it to this thread rather than start
another.  Comments?

On Wed, Jun 25, 2008 at 12:08 PM, Michael Wright <michaelwri22 at yahoo.co.uk>
wrote:

> Yes those are great if we can acheive them. I'm just not sure how we create
> a "clean" wrapper that is independant of Mono.addins, as it uses various
> attributes to define the interfaces and plugins (TypeExtensionPoint,
> Extension, etc) . So those classes need references to mono.addins.
>
> Like for example our current IApplicationPlugin:
>
> using Mono.Addins;
>
> [assembly : AddinRoot("OpenSim", "0.5")]
>
> namespace OpenSim
> {
>     [TypeExtensionPoint("/OpenSim/Startup")]
>     public interface IApplicationPlugin
>     {
>         void Initialise(OpenSimBase openSim);
>         void Close();
>     }
> }
>
> and to implement a Application plugin:
>
> assembly : Addin]
> [assembly : AddinDependency("OpenSim", "0.5")]
> [assembly : AddinDependency("RegionProxy", "0.1")]
>
> namespace OpenSim.ApplicationPlugins.LoadBalancer
> {
>     [Extension("/OpenSim/Startup")]
>     public class LoadBalancerPlugin : IApplicationPlugin
>     {
>
>
> So if we had more classes that used were loaded by mono.addins, we would
> need the interfaces to have a TypeExtensionPoint attribute and the
> implementations to have the Extension. Tthe only other way I saw for
> Mono.addings to load plugins without those attributes, is by using its xml
> manifest files. And one of our requirements is listed as that we don't use
> third party config files.
>
> I most likely haven't dug deep enough into mono.addins and there could well
> be a method to do cut out the attributes and not require manifest files. But
> anyway my point is that I believe a implied effect of those requirements is
> that we don't have references to Mono.addins in the core opensim assemblys.
> (OpenSim.Framework.X , etc)
>
> *Dr Scofield <DrScofield at xyzzyxyzzy.net>* wrote:
>
> Stefan Andersson wrote:
> > Just to get this straight, is what we're saying
> >
> > 1) Yes, we will have a common loader architecture
> > 2) Yes, it will be implemented as a set of interfaces
> > 3) Yes, we will create one implementation as a wrapper around Mono.Addins
> > 4) Yes, we will aim at having a common setup file structure for
> > OpenSim, not depend on lots of different third-party components config.
> >
> > That sounds excellent to me.
> +1
> >
> > Best regards,
> > Stefan Andersson
> > Tribal Media AB
> >
> > Join the 3d web revolution : http://tribalnet.se/
> >
> >
> >
> >
> > ------------------------------------------------------------------------
> >
> > > Date: Wed, 25 Jun 2008 10:16:34 -0400
> > > From: sean at dague.net
> > > To: opensim-dev at lists.berlios.de
> > > Subject: Re: [Opensim-dev] Module/Plugin Loading
> > >
> > > On Wed, Jun 25, 2008 at 03:12:45PM +0100, Melanie wrote:
> > > > I believe that we should use a plugin loader that allows us to
> > > > configure plugin loading completely within our own .ini files. I
> > > > think that a requirement to tweak complex XML based mono/.NET config
> > > > files to get a plugin loaded will put running OpenSim out fo reach
> > > > of many users.
> > > >
> > > > That said, I'm all for a standardized way to load a plugin. I just
> > > > think it shouldn't be required to edit conifg files outside of
> > > > OpenSim's own.
> > >
> > > +1. I think that ryan's plugin loader approach will give us that (at
> > > least from what I've seen in his patch and description). I'm looking
> > > forward to that work.
> > >
> > > -Sean
> > >
> > > --
> > > __________________________________________________________________
> > >
> > > Sean Dague Mid-Hudson Valley
> > > sean at dague dot net Linux Users Group
> > > http://dague.net http://mhvlug.org
> > >
> > > There is no silver bullet. Plus, werewolves make better neighbors
> > > than zombies, and they tend to keep the vampire population down.
> > > __________________________________________________________________
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Opensim-dev mailing list
> > Opensim-dev at lists.berlios.de
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> >
>
>
> --
> dr dirk husemann ---- virtual worlds research ---- ibm zurich research lab
> SL: dr scofield ---- drscofield at xyzzyxyzzy.net ---- http://xyzzyxyzzy.net/
> RL: hud at zurich.ibm.com - +41 44 724 8573 - http://www.zurich.ibm.com/~hud/
>
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