gnosus - Meetup

XMPP Virtual Hosting
with ejabberd and
Nitrogen
by Troy Stribling
Wednesday, June 15, 2011
Outline
• Overview
• Architecture
• Implementation
• Demo
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What is XMPP Virtual
Hosting?
• Hosting multiple XMPP domains on a single
XMPP server.
• Much like HTTP virtual hosting.
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Goal of Project
• Self serve on demand XMPP virtual hosting
web service.
• Virtual Host Administration Console
• Web based XMPP Client
• Prototype running at: http://gnos.us
• Source: https://github.com/troystribling/
gnosus
Wednesday, June 15, 2011
Architecture
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Technologies
• Erlang OTP: Mnesia
• Mociweb: App Server
• Nginx: Web Server
• ejabberd: XMPP Server
• Nitrogen: Web Framework,Virtual Host
Administration Console
• Strophe.js: BOSH Client, Web Based XMPP
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ejabberd
• Open Source XMPP Server written in
Erlang
• Process One: http://www.process-one.net/
en/ejabberd/
• Source: https://github.com/processone/
ejabberd
• My fork: https://github.com/troystribling/
ejabberd
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Nitrogen
• Open source Erlang web framework, http://
nitrogenproject.com/
• Developed by Rusty Klophause: http://
rustyklophaus.com/
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Strophe.js
• Open source javascript XMPP BOSH
Client, http://strophe.im/strophejs/
• Developed by Jack Moffitt: http://
metajack.im/
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Architecture
Web
Client
BOSH
web browser
Erlang RPC
Admin
Console Mnesia
Mnesia
Db
Db
beam
password
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ejabberd
Mirrored
beam
Mnesia
Db
Implementation
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Tasks
• Modify ejabberd to not require reboot
when virtual host added
• Administration Console implemented as
Nitrogen web application.
• Web Client
• Administration Console to ejabberd
interfaces for virtual host provisioning and
authentication
Wednesday, June 15, 2011
ejabberd Customization
The open source version of ejabberd loads
virtual domains from ejabberd.cfg. To add or
delete a domains a reboot is required to reread
the config file.
Changes were made so that virtual domains
could be added or deleted without a reboot.
Less than100 total lines of code needed to be
added to only four files
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Files Changed
File
Change
Removed code that purged host database on
ejabberd_config.erl start. Added methods to add and remove
host from database.
ejabberd_local.erl
Added methods to create and delete servers
that managed C2S and S2S connections and
message routing for virtual host.
Added ,methods to register and unregister
callbacks used for host message processing.
acl.erl
Added method to delete ACL from database.
mod_caps.erl
Fixed bug where CAPS message processing
serever was not completely cleaned up when
parent server was deleted.
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Administration Console
• Nitrogen web application
• Create/Delete virtual hosts
• Create/Delete virtual host users
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Nitrogen Overview
• No Controllers
• Uses layouts but not view templates instead
view is written in Erlang and referred to a
pages by Nitrogen
• Pages use Erlang record based DSL with
some method calls to generate HTML and
javascript.
• Routes hardcoded in module name
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Template Example
Callback to body() method on page. Here page
module is part of Nitrogen framework.
<div id="body-wrapper">
<div id="body">
[[[page:body()]]]
</div>
</div>
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Page Module Example
Nitrogen hooks in page module
-module (web_index).
-include_lib("nitrogen/include/wf.inc").
main() ->
#template{file="./wwwroot/template.html"}.
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Page Module Example
Page Module body() method
body() ->
Body = [
#p{body=[#label{text="uid"},
#textbox{id=userTextBox,next=loginButton},
#link{id=loginButton, text="login",
postback=login, class="button"}],
class="form login"},
wf:wire(loginButton, userTextBox,
#validate{validators=[
#is_required{text="uid required"}]}),
wf:render(Body).
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Page Module Example
Page module login postback
event(login) ->
[Uid] = wf:html_encode(wf:q(userTextBox)),
case user_model:authorize(Uid) of
true ->
wf:flash("authorized")
false ->
wf:flash("unauthorized")
end;
event(_) -> ok.
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Administration Console
ejabberd Interface
• Erlang RPCs for virtual host provisioning
• Mirror of ejabberd password database for
authentication
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Erlang Cookies
• Adminstration Console and ejabberd run
in seperate Erlang VMs.
• Erlang cookies must match for RPCs and
database mirror to work.
• Erlang cookie can be set using
the .erlang_cookie file or the --set-cookie
erl command line option. Here
the .erlang_cookie file is used.
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Erlang VM Names
• Erlang VMs must have unique names to
communicate
• VM names are set using the -sname option
of the erl command
• Names are of the form name@host, where
host is the network address.
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Erlang RPC Syntax
General Syntax
rpc:call(name@host, module_name, method_name,
[arg1, arg2, ..., agrn])
Example: Register User for Virtual Host from
Administration Console
rpc:call(ejabberd@localhost, ejabberd_admin,
register, [Uid, Host, Password])
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Database Mirror
Add remote node database using extra_db_nodes
option for erl command
erl -mnesia extra_db_nodes "['ejabberd@$HOST']"
Create local RAM copy of database table
mnesia:add_table_copy(table, node(), ram_copies).
Wednesday, June 15, 2011
Demo
https://github.com/troystribling/ejabberd
https://github.com/troystribling/gnosus
https://gnos.us
Wednesday, June 15, 2011