Re: [Bodington-developers] Plugin interface

[Adam M. <ada...@co...>]

Plugins are something that Boding desparately needs, perhaps we should de=
dicate
some time to work with Al after our new WebLearn release?

adam

In message <7A5...@sm...>
bod...@li... writes:
> damn list - I didn't get the original of this message and it came =20
> from me!
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> > Can you create a subclass of Facility?
> I think Facility is a lost cause. We'll wait for Tetra!
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> Thinking about maybe specific plugins - ScreenPlugin - writes to =20
> screen, DBPlugin - does stuff with the DB. It's just a way to =20
> refactor code out of Facility into small packages of functionality =20
> that can better be merged etc. Dare I even say, configured at run =20
> time too, ala struts/spring (I see cabbages heading my way).
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> The basic idea is to have, say, a plugins package in bod:
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> org.bodington.plugin
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> and have specific interfaces in there:
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> ScreenPlugin
> DBPlugin
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> public interface ScreenPlugin {
>    public void run(Request req, PrintWriter writer) throws UP;
> }
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> not saying that's what they should be called, just to illustrate.
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> Template then calls Facility.writeModuleLinks
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> Facility.writeModuleLinks (Request req, PrintWriter writer) {
>    ScreenPlugin minerva =3D (ScreenPlugin)Class.forName=20
> ("org.bodington.contrib.Minerva");
>    minerva.run(req, writer):
> }
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> maybe as you say, use a subclass of Facility as a facade for the plugin=
.
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> public class MinervaHelper extends Facility {
>    writeModuleLinks( ... ) {
>      ScreenPlugin ...
>    }
> }
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> so a template calls a plugin's facade - MinervaHelper - class instead =20
> of Facility
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> Can a template call methods in more than one class though? i.e. it =20
> might need functionality that's in more than one plugin.
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> Alistair
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>=20
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> On 22 Mar 2006, at 10:17, Matthew Buckett wrote:
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> > Alistair Young wrote:
> >> Bodders, I've been delurked, damn, to ask opinions.
> >>
> >> We have a requirement for My Modules, which is specific to us so =20
> >> we don't
> >> want to pollute Facility. However, a template must call facility =20
> >> to get it
> >> to write stuff to the screen.
> >
> > Can you create a subclass of Facility?
> >
> >> The writing is delegated to another class which is currently in
> >> org.bodington.contrib on our HEAD but Facility still needs to know =20
> >> about
> >> the class to delegate to it - it has to cast to call methods etc, =20
> >> so it
> >> has to know about the specific class.
> >
> > At least the delegate methods should be small. This is how I pulled =20
> > the
> > StyleSheet code out on WebLearn HEAD. There is still the problem that
> > Facility ends up with 100s of method calls.
> >
> >> A better way would be to define, e.g.
> >>
> >> package org.bodington.contrib;
> >>
> >> public interface Plugin {
> >>   public void run(Request req, PrintWriter writer) throws
> >> SomeOrribleException;
> >> }
> >>
> >> then our class could implement Plugin and Facility would only have =20
> >> to load
> >> it via Class.forName as a Plugin and call it's run method.
> >
> > Can you explain the call graph a little more.
> >
> >> It reduces the code in Facility and brings a sort of IOC/dependancy
> >> injection to Facility.
> >>
> >> What would be even better though is allowing templates to call =20
> >> whatever
> >> class they wanted and not just Facility or a subclass thereof.
> >
> > I added support for making static calls from template but I don't =20
> > think
> > this is a good move as then it becomes move difficult to refactor cod=
e
> > as you can't be sure without recompiling the templates if a method is
> > actually used. At the moment you only have todo this checking when
> > working with public methods in Facility. It also means that the =20
> > idea of
> > linking a template with a Facility in a configuration file breaks =20
> > down.
> >
> >
> > --=20
> >  -- Matthew Buckett, VLE Developer
> >  -- Learning Technologies Group, Oxford University Computing Services
> >  -- Tel: +44 (0)1865 283660 http://www.oucs.ox.ac.uk/ltg/
> >
> >
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> > https://lists.sourceforge.net/lists/listinfo/bodington-developers
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--=20
--
Dr AC Marshall (Bodington developer) OUCS, 13, Banbury Rd. Oxford. OX2 6N=
N
               Cheese of the month: Smoked Wensleydale