Crystal XMPP

Pure Crystal XMPP Shard, focusing on simplicity, simple automation, and IoT.

The goal is to make simple to write simple XMPP clients and components. It features:

• Fully OOP
• Aims at being XMPP compliant
• Event Based
• Easy to extend
• For automation (like for example monitoring of an XMPP service),
• For building connected "things" by plugging them on an XMPP server,
• For writing simple chatbot to control a service or a thing,
• For writing XMPP servers components.

You can basically do everything you want with cr-xmpp. It fully supports XMPP Client and components specification, and also a wide range of extensions (XEPs). And it's very easy to extend :)

This Shard does not have any other dependencies.

Supported specifications

Clients

• RFC 6120: XMPP Core
• RFC 6121: XMPP Instant Messaging and Presence

Components

• XEP-0114: Jabber Component Protocol
• XEP-0355: Namespace Delegation
• XEP-0356: Privileged Entity

XEP Extensions

• XEP-0030 - Service Discovery
• XEP-0045 - Multi-User Chat - 19.1
• XEP-0060 - Publish-Subscribe
• XEP-0066 - Out of Band Data
• XEP-0085 - Chat State Notifications
• XEP-0092 - Software Version
• XEP-0107 - User Mood
• XEP-0153 - vCard-Based Avatars
• XEP-0184 - Message Delivery Receipts
• XEP-0198 - Stream Management
• XEP-0199 - XMPP Ping
• XEP-0203 - Delayed Delivery
• XEP-0333 - Chat Markers
• XEP-0334 - Message Processing Hints

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     cr-xmpp:
       github: naqvis/cr-xmpp

2. Run shards install

Usage

require "cr-xmpp"

config = XMPP::Config.new(
  host: "localhost",
  jid: "test@localhost",
  password: "test",
  log_file: STDOUT,   # Capture all out-going and in-coming messages
  # Order of SASL Authentication Mechanism, first matched method supported by server will be used
  # for authentication. Below is default order that will be used if `sasl_auth_order` param is not set.
  sasl_auth_order: [XMPP::AuthMechanism::SCRAM_SHA_512, XMPP::AuthMechanism::SCRAM_SHA_256,
                    XMPP::AuthMechanism::SCRAM_SHA_1, XMPP::AuthMechanism::DIGEST_MD5,
                    XMPP::AuthMechanism::PLAIN, XMPP::AuthMechanism::ANONYMOUS]
)

router = XMPP::Router.new

# router.on "presence" do |_, p|  # OR
router.presence do |_, p|
  if (msg = p.as?(XMPP::Stanza::Presence))
    puts msg
  else
    puts "Ignoring Packet: #{p}"
  end
end

# router.when "chat" do |s, p| # OR
router.message do |s, p|
  handle_message(s, p)
end

# OR
# router.on "message", ->handle_message(XMPP::Sender, XMPP::Stanza::Packet)

client = XMPP::Client.new config, router
# If you pass the client to a connection manager, it will handle the reconnect policy
# for you automatically
sm = XMPP::StreamManager.new client
sm.run


def handle_message(s : XMPP::Sender, p : XMPP::Stanza::Packet)
  if (msg = p.as?(XMPP::Stanza::Message))
    puts "Got message: #{msg.body}"
    reply = XMPP::Stanza::Message.new
    reply.to = msg.from
    reply.body = "#{msg.body}"
    s.send reply
  else
    puts "Ignoring Packet: #{p}"
  end
end

Refer to examples for more usage details.

Development

XMPP stanzas are basic and extensible XML elements. Stanzas (or sometimes special stanzas called 'nonzas') are used to leverage the XMPP protocol features. During a session, a client (or a component) and a server will be exchanging stanzas back and forth.

At a low-level, stanzas are XML fragments. However, this shard provides the building blocks to interact with stanzas at a high-level, providing a Crystal-friendly API.

The XMPP::Stanza module provides support for XMPP stream parsing, encoding and decoding of XMPP stanza. It is a bridge between high-level Crystal classes and low-level XMPP protocol.

Parsing, encoding and decoding is automatically handled by Crystal XMPP client shard. As a developer, you will generally manipulates only the high-level classes provided by the XMPP::Stanza module.

The XMPP protocol, as the name implies is extensible. If your application is using custom stanza extensions, you can implement your own extensions directly.

Custom Stanza Support

Below example show how to implement a custom extension for your own client, without having to modify or fork Crystal XMPP shard.

class CustomExtension < Extension
    include IQPayload
    class_getter xml_name : XMLName = XMLName.new("my:custom:payload query")
    property node : String = ""

    def self.new(node : XML::Node)
      raise "Invalid node(#{node.name}, expecting #{@@xml_name.to_s}" unless (node.namespace.try &.href == @@xml_name.space) &&
                                                                             (node.name == @@xml_name.local)
      cls = new()
      node.children.select(&.element?).each do |child|
      case child.name
        when "item" then cls.node = child.content
        end
      end
      cls
    end

    def to_xml(elem : XML::Builder)
      elem.element(@@xml_name.local, xmlns: @@xml_name.space) do
        elem.element("node") { elem.text node } unless node.blank?
      end
    end

    def namespace : String
      @@xml_name.space
    end

    def name : String
      @@xml_name.local
    end
  end

  Registry.map_extension(PacketType::IQ, XMLName.new("my:custom:payload", "query"), CustomExtension)

Contributing

1. Fork it (https://github.com/naqvis/cr-xmpp/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Ali Naqvi - creator and maintainer