6:24 p.m.
----- Original Message -----
From: "R P Herrold" <herrold(a)owlriver.com>
To: "oVirt Users ML" <users(a)ovirt.org>
Cc: "aditya mamidwar" <aditya.mamidwar(a)gmail.com>
Sent: Friday, March 21, 2014 3:43:27 PM
Subject: [Users] adding scripts
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(a)gmail.com>
>> To: awels(a)redhat.com, engine-devel(a)ovirt.org, users(a)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)
Right, UI plugins are written in JavaScript as their code is dynamically loaded during
WebAdmin startup.
Your UI plugin is technically a web application on its own, except that plugin host page
[1] is rendered inside invisible <iframe> element.
[1] plugin host page = HTML page responsible for loading actual UI plugin code (no markup,
just logic)
UI plugin code can make HTTP requests just like any other web application. This is how you
would invoke operations on remote servers.
The easiest way (I think) is to add custom CGI/Bash script into Apache which sits in front
of Engine (JBoss AS) server in a typicall oVirt deployment. Your UI plugin would simply
hit URL mapped to custom CGI/Bash script, which would execute whatever command is
necessary.
Alternatively, you could deploy custom Java web application (*.war) inside Engine Java
deployment (engine.ear) so that it co-exists with existing Engine web applications (REST
API, WebAdmin, UserPortal, etc).
Finally, a totally custom alternative, run your own HTTP server, enable CORS [2] for
requests from Engine origin, and have your UI plugin talk to this custom server.
[2] http://en.wikipedia.org/wiki/Cross-origin_resource_sharing
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
Correct, UI plugin itself is JavaScript, it makes no assumptions of server-side
technology.
It is up to UI plugin developer to decide if/how the plugin should communicate with remote
servers (Engine REST API, call Apache CGI, call custom server, etc).
Thank you
-- Russ herrold
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