Blather

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

develop branch contains breaking changes scheduled for release in v3.0.0

Features

• evented architecture
• uses Nokogiri
• simplified starting point

Project Pages

• GitHub
• Rubygems
• API Documentation
• Google Group

Usage

Installation

gem install blather

Example

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

require 'blather/client'

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

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

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

The above example is for a standalone script, and can be run as a command line program. If you wish to integrate Blather into an existing application, you will need to avoid blather/client and instead do something like this:

require 'blather/client/dsl'

module App
  extend Blather::DSL

  def self.run
    EM.run { client.run }
  end

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

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

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

trap(:INT) { EM.stop }
trap(:TERM) { EM.stop }

App.run

If you need to ensure that Blather does not block the rest of your application, run the reactor in a new thread:

Thread.new { App.run }

You can additionally send messages like so:

App.say 'foo@bar.com', 'Hello there!'

Handlers

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.

Example

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
end

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

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.chat? && 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 stanza.chat?
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.name)
stanza_error :name => [:gone, :fobidden]

# Proc
#   Calls the proc passing in the stanza
#   Checks that the ID is modulo 3
message proc { |m| m.id % 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
end

Filters

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

stanza
|- 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

error
|- 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] node@domain.com/resource 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	Name	Notes
RFC 6120	Full	XMPP: Core
RFC 6121	Full	XMPP: Instant Messaging and Presence
RFC 6122	Full	XMPP: Address Format
XEP-0001	N/A	XMPP Extension Protocols
XEP-0002	N/A	Special Interest Groups (SIGs)
XEP-0004	Partial	Data Forms
XEP-0009	None	Jabber-RPC
XEP-0012	None	Last Activity
XEP-0013	None	Flexible Offline Message Retrieval
XEP-0016	None	Privacy Lists
XEP-0019	N/A	Streamlining the SIGs
XEP-0020	Partial	Feature Negotiation
XEP-0027	None	Current Jabber OpenPGP Usage
XEP-0030	Partial	Service Discovery
XEP-0033	None	Extended Stanza Addressing
XEP-0045	Partial	Multi-User Chat
XEP-0047	None	In-Band Bytestreams
XEP-0048	None	Bookmarks
XEP-0049	None	Private XML Storage
XEP-0050	Partial	Ad-Hoc Commands
XEP-0053	None	XMPP Registrar Function
XEP-0054	None	vcard-temp
XEP-0055	None	Jabber Search
XEP-0059	None	Result Set Management
XEP-0060	Partial	Publish-Subscribe
XEP-0065	None	SOCKS5 Bytestreams
XEP-0066	None	Out of Band Data
XEP-0068	None	Field Standardization for Data Forms
XEP-0070	None	Verifying HTTP Requests via XMPP
XEP-0071	Partial	XHTML-IM
XEP-0072	None	SOAP Over XMPP
XEP-0076	None	Malicious Stanzas
XEP-0077	Full	In-Band Registration
XEP-0079	None	Advanced Message Processing
XEP-0080	None	User Location
XEP-0082	None	XMPP Date and Time Profiles
XEP-0083	None	Nested Roster Groups
XEP-0084	None	User Avatar
XEP-0085	Partial	Chat State Notifications
XEP-0092	None	Software Version
XEP-0095	Partial	Stream Initiation
XEP-0096	Partial	SI File Transfer
XEP-0100	None	Gateway Interaction
XEP-0106	None	JID Escaping
XEP-0107	None	User Mood
XEP-0108	None	User Activity
XEP-0114	Full	Jabber Component Protocol
XEP-0115	Partial	Entity Capabilities
XEP-0118	None	User Tune
XEP-0122	None	Data Forms Validation
XEP-0124	None	Bidirectional-streams Over Synchronous HTTP (BOSH)
XEP-0126	None	Invisibility
XEP-0127	None	Common Alerting Protocol (CAP) Over XMPP
XEP-0128	None	Service Discovery Extensions
XEP-0130	None	Waiting Lists
XEP-0131	None	Stanza Headers and Internet Metadata
XEP-0132	None	Presence Obtained via Kinesthetic Excitation (POKE)
XEP-0133	None	Service Administration
XEP-0134	None	XMPP Design Guidelines
XEP-0136	None	Message Archiving
XEP-0137	None	Publishing Stream Initiation Requests
XEP-0138	None	Stream Compression
XEP-0141	None	Data Forms Layout
XEP-0143	None	Guidelines for Authors of XMPP Extension Protocols
XEP-0144	N/A	Roster Item Exchange
XEP-0145	None	Annotations
XEP-0146	None	Remote Controlling Clients
XEP-0147	None	XMPP URI Scheme Query Components
XEP-0148	None	Instant Messaging Intelligence Quotient (IM IQ)
XEP-0149	None	Time Periods
XEP-0153	None	vCard-Based Avatars
XEP-0155	None	Stanza Session Negotiation
XEP-0156	None	Discovering Alternative XMPP Connection Methods
XEP-0157	None	Contact Addresses for XMPP Services
XEP-0158	None	CAPTCHA Forms
XEP-0160	None	Best Practices for Handling Offline Messages
XEP-0163	Partial	Personal Eventing Protocol
XEP-0166	None	Jingle
XEP-0167	None	Jingle RTP Sessions
XEP-0169	None	Twas The Night Before Christmas (Jabber Version)
XEP-0170	None	Recommended Order of Stream Feature Negotiation
XEP-0171	None	Language Translation
XEP-0172	None	User Nickname
XEP-0174	None	Serverless Messaging
XEP-0175	None	Best Practices for Use of SASL ANONYMOUS
XEP-0176	None	Jingle ICE-UDP Transport Method
XEP-0177	None	Jingle Raw UDP Transport Method
XEP-0178	None	Best Practices for Use of SASL EXTERNAL with Certificates
XEP-0182	N/A	Application-Specific Error Conditions
XEP-0183	None	Jingle Telepathy Transport
XEP-0184	None	Message Delivery Receipts
XEP-0185	None	Dialback Key Generation and Validation
XEP-0191	None	Blocking Command
XEP-0198	None	Stream Management
XEP-0199	Partial	XMPP Ping
XEP-0201	None	Best Practices for Message Threads
XEP-0202	None	Entity Time
XEP-0203	Partial	Delayed Delivery
XEP-0205	None	Best Practices to Discourage Denial of Service Attacks
XEP-0206	None	XMPP Over BOSH
XEP-0207	None	XMPP Eventing via Pubsub
XEP-0220	None	Server Dialback
XEP-0221	None	Data Forms Media Element
XEP-0222	None	Persistent Storage of Public Data via PubSub
XEP-0223	None	Persistent Storage of Private Data via PubSub
XEP-0224	None	Attention
XEP-0227	None	Portable Import/Export Format for XMPP-IM Servers
XEP-0229	None	Stream Compression with LZW
XEP-0231	None	Bits of Binary
XEP-0233	None	Domain-Based Service Names in XMPP SASL Negotiation
XEP-0234	None	Jingle File Transfer
XEP-0239	None	Binary XMPP
XEP-0242	None	XMPP Client Compliance 2009
XEP-0243	None	XMPP Server Compliance 2009
XEP-0245	None	The /me Command
XEP-0249	None	Direct MUC Invitations
XEP-0256	None	Last Activity in Presence
XEP-0258	None	Security Labels in XMPP
XEP-0260	None	Jingle SOCKS5 Bytestreams Transport Method
XEP-0261	None	Jingle In-Band Bytestreams Transport Method
XEP-0262	None	Use of ZRTP in Jingle RTP Sessions
XEP-0263	None	ECO-XMPP
XEP-0266	None	Codecs for Jingle Audio
XEP-0267	None	Server Buddies
XEP-0270	None	XMPP Compliance Suites 2010
XEP-0273	None	Stanza Interception and Filtering Technology (SIFT)
XEP-0277	None	Microblogging over XMPP
XEP-0278	None	Jingle Relay Nodes
XEP-0280	None	Message Carbons
XEP-0288	None	Bidirectional Server-to-Server Connections
XEP-0292	None	vCard4 Over XMPP
XEP-0293	None	Jingle RTP Feedback Negotiation
XEP-0294	None	Jingle RTP Header Extensions Negotiation
XEP-0295	None	JSON Encodings for XMPP
XEP-0296	None	Best Practices for Resource Locking
XEP-0297	None	Stanza Forwarding
XEP-0298	None	Delivering Conference Information to Jingle Participants (Coin)
XEP-0299	None	Codecs for Jingle Video
XEP-0300	None	Use of Cryptographic Hash Functions in XMPP
XEP-0301	None	In-Band Real Time Text
XEP-0302	None	XMPP Compliance Suites 2012
XEP-0303	None	Commenting
XEP-0304	None	Whitespace Keepalive Negotiation
XEP-0305	None	XMPP Quickstart
XEP-0306	None	Extensible Status Conditions for Multi-User Chat
XEP-0307	None	Unique Room Names for Multi-User Chat
XEP-0308	None	Last Message Correction
XEP-0309	None	Service Directories
XEP-0310	None	Presence State Annotations
XEP-0311	None	MUC Fast Reconnect
XEP-0312	None	PubSub Since

Contributions

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.

Author

• Jeff Smick
• Other Contributors

Copyright

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