DesignXMPP analysis

Version 5 (Anonymous, 03/01/2012 02:16 pm) → Version 6/17 (Anonymous, 03/01/2012 02:21 pm)

= XMPP library candidates analysis =

[[TOC(DesignXMPP, DesignXMPP_analysis, DesignXMPP_arch, DesignXMPP_im, depth=2)]]

In this phase the existing XMPP libraries will be analyzed and one will be chosen to be used throughout the project.

== Library requirements ==

* Written in Python (C/C++ could also be used, but a wrapper would need to be written)
* Support for XMPP server (or component, details later)
* Ability to use it with the current model used by SylkServer
* Green threads
* Callback based IO

== XMPP server vs XMPP component

The XMPP protocol was designed to be extended by entities called "components" which sit on the side of the server. A component is addressed with a DNS subdomain in the following form:

{{{
component.domain.tld
}}}

This mechanism is defined in [http://xmpp.org/extensions/xep-0114.html XEP-0114].

With this architecture in place deployment of additional features to an existing XMPP server doesn't require to modify it. The SIP-XMPP gateway can potentially be implemented as either a XMPP component or an standalone XMPP server.

== Library evaluation ==

The following aspects were considered when evaluating a given library:

* Met requirements stated above
* Is it actively maintained?
* Example use cases
* Deployments in real-world scenarios
* Perceived complexity to integrate it with SylkServer architecture

=== SleekXMPP===

* Plugin architecture, each XEP as a plugin
* Client and server component support
* Threaded model (thread based scheduler)
* Active development

=== Wokkel ===

* Plugin architecture, 'subprotocols' implementing different XEPs
* Client and server component support
* XMPP server-to-server support (s2s)
* Designed to be used with Twisted (reactor model)
* Active development

== Selected XMPP library ==

After analyzing candidate libraries '''Wokkel''' was the chosen one. Reasons:

* Implemented on top of Twisted, which makes integration with SylkServer straightforward
* Support for both component and XMPP server models, allowing for flexibility in implementation