[Users] adding scripts

[Alexander Wels]

On Friday, March 21, 2014 10:43:27 AM R P Herrold wrote:
> the threading is not clear to me, and I hope I have the
> attributions correct
> 
> On Fri, 21 Mar 2014, Greg Sheremeta wrote:
> >> From: "aditya mamidwar" <aditya.mamidwar at gmail.com>
> >> 
> >> To: awels at redhat.com, engine-devel at ovirt.org, users at ovirt.org
> >> Sent: Friday, March 21, 2014 6:14:01 AM
> >> Subject: Re: [Users] [Engine-devel] adding scripts
> >> 
> >> am thus facing following difficulties:
> >> 
> >> 1 : i wrote the required code using in bash scripting,
> >> which i wish to invoke after a click of button in the
> >> ovirt-portal. (which does not seem to be possible). can you
> >> help on that? which programming language should i use, and
> >> how that file should be invoked.
> 
> [I think Greg said:]
> 
> > This needs to be done in Java. You'll need to read up on
> > oVirt's UI Plugin infrastructure, which Einav and others
> > mentioned below. No, you cannot write a bash script and have
> > a button click in oVirt invoke that.
> 
> Reading this:
> 	http://www.ovirt.org/VDSM-Hooks
> it states as a pull quote:
> 
> 	The hooks reside on every host in
> 	/usr/libexec/vdsm/hooks/ A hook can be any executable
> 	(bash/python/perl/binary/etc).
> 
> and then at:
> 	http://www.ovirt.org/Features/UIPlugins
> 
> 	UI plugins integrate with WebAdmin directly on the
> 	client (web browser) using JavaScript programming language.
> 	Plugin invocation is driven by WebAdmin and happens right
> 	within the context of browser's JavaScript runtime, using
> 	JavaScript language as the lowest common denominator between
> 	WebAdmin (GWT) and individual plugins. UI plugins can take
> 	full advantage of JavaScript language and its rich ecosystem
> 	of libraries. There are no specific rules on how to implement
> 	UI plugins, plugin API is designed to be simple and not to get
> 	in developer's way, regardless of how a developer chooses to
> 	write the plugin
> 
> ============
> 
> I thought I understood the model, but have gotten confused.
> Iam left with two questions:
> 
> 1. is the plugin to be Java or JavaScript? (I think the answer
> is the latter)
> 

Javascript. But remember the UI plugins are running javascript in your 
browser, and don't directly communicate with VDSM.

> 2. is there a constraint as to implementation language, or
> not. I think a JS wrapper can call whatever it wishes, but
> this is not clear to me
> 
> Thank you
> 
> -- Russ herrold

Note the VDSM hooks have nothing to do with the UI plugins. The VDSM hooks 
alter the way VDSM works. The UI plugins alter the way the UI works. The 
engine sits in between the UI and VDSM. Basically the UI issues a command to 
the engine, then the engine issues a command to VDSM.

For UI plugins it is easiest to communicate with the engine using the REST 
api. So your instance your UI plugin has a button, which when you click it 
issues a REST api call. The REST api call is part of the engine. The engine 
creates a command based on the URL and parameters of the REST call and uses 
that command to make a call to VDSM. Once the call reaches VDSM then the VDSM 
hooks come into play.

So I don't entirely understand what you are trying to do, but you might have 
to write some code in the engine to create the appropriate command to pass to 
VDSM. In addition to the UI plugin and the VDSM hook.