XMPP/Jabber Library and DSL for Ruby written on EventMachine and Nokogiri.

Blather Build status

XMPP DSL (and more) for Ruby written on EventMachine and Nokogiri.


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gem install blather


Blather comes with a DSL that makes writing XMPP bots quick and easy. See the examples directory for more advanced examples.

require 'rubygems'
require 'blather/client'

setup 'echo@jabber.local', 'echo'

# Auto approve subscription requests
subscription :request? do |s|
  write_to_stream s.approve!

# Echo back what was said
message :chat?, :body do |m|
  write_to_stream m.reply


Handlers let Blather know how you'd like each type of stanza to be well.. handled. Each type of stanza has an associated handler which is part of a handler hierarchy. In the example above we're handling message and subscription stanzas.

XMPP is built on top of three main stanza types (presence, message, and iq). All other stanzas are built on these three base types. This creates a natural hierarchy of handlers. For example a subscription stanza is a type of presence stanza and can be processed by a subscription handler or a presence handler. Likewise, a PubSub::Items stanza has its own identifier :pubsub_items but it's also a :pubsub_node, :iq and :staza. Any or each of these could be used to handle the PubSub::Items stanza. If you've done any DOM programming you'll be familiar with this.

Incoming stanzas will be handled by the first handler found. Unlike the DOM this will stop the handling bubble unless the handler returns false.

The entire handler hierarchy can be seen below.


Here we have a presence handler and a subscription handler. When this script receives a subscription stanza the subscription handler will be notified first. If that handler doesn't know what to do it can return false and let the stanza bubble up to the presence handler.

# Handle all presence stanzas
presence do |stanza|
  # do stuff

# Handle all subscription stanzas
subscription do |stanza|
  # do stuff

Additionally, handlers may be 'guarded'. That is, they may have conditions set declaratively, against which the stanza must match in order to trigger the handler.

# Will only be called for messages where #chat? responds positively
# and #body == 'exit'
message :chat?, :body => 'exit'

Non-Stanza Handlers

So far there are two non-stanza related handlers.

# Called after the connection has been connected. It's good for initializing
# your system.
# DSL:
when_ready {}
# Client:
client.register_handler(:ready) {}

# Called after the connection has been terminated. Good for teardown or
# automatic reconnection.
# DSL:
disconnected {}
# Client
client.register_handler(:disconnected) {}
# The following will reconnect every time the connection is lost:
disconnected { client.connect }

Handler Guards

Guards are a concept borrowed from Erlang. They help to better compartmentalize handlers.

There are a number of guard types and one bit of special syntax. Guards act like AND statements. Each condition must be met if the handler is to be used.

# Equivalent to saying ( && stanza.body)
message :chat?, :body

The different types of guards are:

# Symbol
#   Checks for a non-false reply to calling the symbol on the stanza
#   Equivalent to
message :chat?

# Hash with any value (:body => 'exit')
#   Calls the key on the stanza and checks for equality
#   Equivalent to stanza.body == 'exit'
message :body => 'exit'

# Hash with regular expression (:body => /exit/)
#   Calls the key on the stanza and checks for a match
#   Equivalent to stanza.body.match /exit/
message :body => /exit/

# Hash with array (:name => [:gone, :forbidden])
#   Calls the key on the stanza and check for inclusion in the array
#   Equivalent to [:gone, :forbidden].include?(
stanza_error :name => [:gone, :fobidden]

# Proc
#   Calls the proc passing in the stanza
#   Checks that the ID is modulo 3
message proc { |m| % 3 == 0 }

# Array
#   Use arrays with the previous types effectively turns the guard into
#   an OR statement.
#   Equivalent to stanza.body == 'foo' || stanza.body == 'baz'
message [{:body => 'foo'}, {:body => 'baz'}]

# XPath
#   Runs the xpath query on the stanza and checks for results
#   This guard type cannot be combined with other guards
#   Equivalent to !stanza.find('/iq/ns:pubsub', :ns => 'pubsub:namespace').empty?
#   It also passes two arguments into the handler block: the stanza and the result
#   of the xpath query.
iq '/iq/ns:pubsub', :ns => 'pubsub:namespace' do |stanza, xpath_result|
  # stanza will be the original stanza
  # xpath_result will be the pubsub node in the stanza


Blather provides before and after filters that work much the way regular handlers work. Filters come in a before and after flavor. They're called in order of definition and can be guarded like handlers.

before { |s| "I'm run before any handler" }
before { |s| "I'm run next" }

before(:message) { |s| "I'm only run in front of message stanzas" }
before(nil, :id => 1) { |s| "I'll only be run when the stanza's ID == 1" }

# ... handlers

after { |s| "I'm run after everything" }

Handlers Hierarchy

|- iq
|  |- pubsub_node
|  |  |- pubsub_affiliations
|  |  |- pubsub_create
|  |  |- pubsub_items
|  |  |- pubsub_publish
|  |  |- pubsub_retract
|  |  |- pubsub_subscribe
|  |  |- pubsub_subscription
|  |  |- pubsub_subscriptions
|  |  `- pubsub_unsubscribe
|  |- pubsub_owner
|  |  |- pubsub_delete
|  |  `- pubsub_purge
|  `- query
|     |- disco_info
|     |- disco_items
|     `- roster
|- message
|  `- pubsub_event
`- presence
   |- status
   `- subscription

|- argument_error
|- parse_error
|- sasl_error
|- sasl_unknown_mechanism
|- stanza_error
|- stream_error
|- tls_failure
`- unknown_response_error

On the Command Line

Default usage is:

[blather_script] [options] password [host] [port]

Command line options:

-D, --debug       Run in debug mode (you will see all XMPP communication)
-d, --daemonize   Daemonize the process
    --pid=[PID]   Write the PID to this file
    --log=[LOG]   Write to the [LOG] file instead of stdout/stderr
-h, --help        Show this message
-v, --version     Show version

Health warning

Some parts of Blather will allow you to do stupid things that don't conform to XMPP spec. You should exercise caution and read the relevant specifications (indicated in the preamble to most relevant classes).

Spec compliance

Blather provides support in one way or another for many XMPP specifications. Below is a list of specifications and the status of support for them in Blather. This list may not be correct. If the list indicates a lack of support for a specification you wish to use, you are encouraged to check that this is correct. Likewise, if you find an overstatement of Blather's spec compliance, please point this out. Also note that even without built-in support for a specification, you can still manually construct and parse stanzas alongside use of Blather's built-in helpers.

Specification Support Notes
RFC 6120 Full
RFC 6121 Full
RFC 6122 Full
XEP-0001 N/A
XEP-0002 N/A
XEP-0004 Partial
XEP-0009 None
XEP-0012 None
XEP-0013 None
XEP-0016 None
XEP-0019 N/A
XEP-0020 Partial
XEP-0027 None
XEP-0030 Partial
XEP-0033 None
XEP-0045 Partial
XEP-0047 None
XEP-0048 None
XEP-0049 None
XEP-0050 Partial
XEP-0053 None
XEP-0054 None
XEP-0055 None
XEP-0059 None
XEP-0060 Partial
XEP-0065 None
XEP-0066 None
XEP-0068 None
XEP-0070 None
XEP-0071 Partial
XEP-0072 None
XEP-0076 None
XEP-0077 None
XEP-0079 None
XEP-0080 None
XEP-0082 None
XEP-0083 None
XEP-0084 None
XEP-0085 Partial
XEP-0092 None
XEP-0095 Partial
XEP-0096 Partial
XEP-0100 None
XEP-0106 None
XEP-0107 None
XEP-0108 None
XEP-0114 Full
XEP-0115 Partial
XEP-0118 None
XEP-0122 None
XEP-0124 None
XEP-0126 None
XEP-0127 None
XEP-0128 None
XEP-0130 None
XEP-0131 None
XEP-0132 None
XEP-0133 None
XEP-0134 None
XEP-0136 None
XEP-0137 None
XEP-0138 None
XEP-0141 None
XEP-0143 None
XEP-0144 N/A
XEP-0145 None
XEP-0146 None
XEP-0147 None
XEP-0148 None
XEP-0149 None
XEP-0153 None
XEP-0155 None
XEP-0156 None
XEP-0157 None
XEP-0158 None
XEP-0160 None
XEP-0163 Partial
XEP-0166 None
XEP-0167 None
XEP-0169 None
XEP-0170 None
XEP-0171 None
XEP-0172 None
XEP-0174 None
XEP-0175 None
XEP-0176 None
XEP-0177 None
XEP-0178 None
XEP-0182 N/A
XEP-0183 None
XEP-0184 None
XEP-0185 None
XEP-0191 None
XEP-0198 None
XEP-0199 Partial
XEP-0201 None
XEP-0202 None
XEP-0203 Partial
XEP-0205 None
XEP-0206 None
XEP-0207 None
XEP-0220 None
XEP-0221 None
XEP-0222 None
XEP-0223 None
XEP-0224 None
XEP-0227 None
XEP-0229 None
XEP-0231 None
XEP-0233 None
XEP-0234 None
XEP-0239 None
XEP-0242 None
XEP-0243 None
XEP-0245 None
XEP-0249 None
XEP-0256 None
XEP-0258 None
XEP-0260 None
XEP-0261 None
XEP-0262 None
XEP-0263 None
XEP-0266 None
XEP-0267 None
XEP-0270 None
XEP-0273 None
XEP-0277 None
XEP-0278 None
XEP-0280 None
XEP-0288 None
XEP-0292 None
XEP-0293 None
XEP-0294 None
XEP-0295 None
XEP-0296 None
XEP-0297 None
XEP-0298 None
XEP-0299 None
XEP-0300 None
XEP-0301 None
XEP-0302 None
XEP-0303 None
XEP-0304 None
XEP-0305 None
XEP-0306 None
XEP-0307 None
XEP-0308 None
XEP-0309 None
XEP-0310 None
XEP-0311 None
XEP-0312 None


All contributions are welcome, even encouraged. However, contributions must be well tested. If you send me a branch name to merge that'll get my attention faster than a change set made directly on master.



Copyright (c) 2012 Adhearsion Foundation Inc. See LICENSE for details.