NAME

Protocol::XMPP - Protocol-level support for XMPP interaction

VERSION

Version 0.006

SYNOPSIS

 my $xmpp = Protocol::XMPP::Stream->new;
 $xmpp->();

DESCRIPTION

This module provides an API for the Extensible Message Passing Protocol. This is commonly used for integration with Jabber servers and Google Talk, although XMPP itself supports a number of extended features for a distributed multi-server, multi-client message exchange system.

The primary implementation is based on RFC3920bis, which is still in flux. The instant message support is defined by RFC3921bis.

The two main classes used here are Protocol::XMPP::Stream, which provides hooks for the underlying XML message stream, and Protocol::XMPP::Handler, which passes the SAX events from this stream on to appropriate handlers.

Client or server implementations should create an instance of the Protocol::XMPP::Stream class for each connection, passing callbacks to allow the protocol implementation to send data over the connection and process received data.

IMPLEMENTATION

An overview of the connection lifetime for a typical client session:

  • Connect to server

  • Establish session, including authentication and stream requirements such as TLS or compression

  • Retrieve roster

  • Send presence update to server

  • Send and receive messages as required

  • Terminate session

The details of connecting to sockets and upgrading to TLS are left to the implementation. This module deals with the underlying protocol stream only, providing hooks that the implementation can call rather than attempting to implement the functionality directly.

Roster

A roster is a list of contacts, each of which may also have presence information. This list is stored on the server, although each client may also maintain a cached copy of the list.

Roster information is exchanged using Protocol::XMPP::IQ::Roster queries and responses.

Roster includes the ver information which is an opaque server token used to identify the version of the roster information.

A roster query has a single item, and the response can have multiple.

Each item may also belong to zero or more groups.

Subscription states:

  • none - neither source nor destination contact have an existing subscription.

  • to - we have a subscription to the contact, but they don't have us.

  • from - they have us, we don't have them.

  • both - mutual subscription.

MOTIVATION

This distribution is written with the intention to provide a base for XMPP implementations which can work on an event-based ("asynchronous") or standard blocking model. It uses XML::LibXML::SAX::ChunkedParser to deal with the XML fragments required by the protocol, and attempts to minimise any blocking operations.

SEE ALSO

  • AnyEvent::XMPP - this is an event-based implementation of XMPP, seems to support the core protocol and some key XEPs such as multi-user chat. The documentation is somewhat terse (rants about XML notwithstanding) but more detailed than Protocol::XMPP.

  • Net::XMPP - another implementation, sadly the XML parser is blocking so although it provides the Net::XMPP::Protocol abstraction layer for the XMPP protocol, which probably has better feature support than this module, it's not too suitable for dealing with asynchronous / event-based implementations. Also, I wasn't too keen on some of the implementation details, such as the direct checking for ref and callback handling.

  • Net::XMPP3::Protocol - seems to be the same module as above, under a slightly different namespace

AUTHOR

Tom Molesworth <protocol-xmpp@entitymodel.com>

CONTRIBUTORS

With thanks to the following for contribution:

  • Arthur Axel "fREW" Schmidt for testing, documentation, pointing out some of my mistakes, that sort of thing

  • Paul "LeoNerd" Evans for adding Futures to IO::Async (and writing both in the first place)

  • Matt Trout for testing early versions

LICENSE

Copyright Tom Molesworth 2010-2014. Licensed under the same terms as Perl itself.