node-xmpp

idiomatic XMPP library for node.js

Now usable in browsers too thanks to Browserify.

Roadmap for 0.4.0

• Events harmonization
• Common pause/resume/... for any Client/Component/Server session
• Smoothen reconnect
• Websockets server (at least for testing the client)
• Lookup BOSH URLs in DNS TXT records
• Move connecting to connection, use WS/BOSH as TCP fallback
• Use split-out srv library
• Ensure tls end/close/drain events
• Properly disconnect on stream errors, not on connection errors
• Tests for S2S connections
• Tests for Component connections (w/ Component server?)
• Find a browser-based demo app that can be switched from Strophe.js

Installation

With package manager npm:

npm install node-xmpp

Objectives of node-xmpp:

• Use node.js conventions, especially EventEmitter, ie. for write buffer control
• Fast parsing, node-expat was written for this library
• Client support for both XMPP clients and components
• Optional server infrastructure with Router
• After authentication, leave trivial protocol bits to the user, that is XML handling according to any XEP

Features

• Client authentication with SASL DIGEST-MD5, PLAIN, ANONYMOUS, X-FACEBOOK-PLATFORM
• _xmpp-client._tcp SRV record support
• Simple JID parsing with Stringprep normalization
  • Optional now, you won't need ICU for just node-xmpp
  • Please be aware if you identify users by JIDs
  • npm install node-stringprep
• Uses ltx
  • Much easier to handle than a standard DOM
  • xmlns-aware
  • Easy XML builder like Strophe.js (see down)
  • Non-buffering serialization
  • Was split out of node-xmpp for modularization and resuability
• Component connections
• Run your own server/talk to other servers with xmpp.Router

Dependencies

• node-expat (requires libexpat!)
• ltx

Optional

• node-stringprep: for icu-based string normalization.

Related Libraries

• node-xmpp-bosh: BOSH & websocket server (connection manager)
• node-xmpp-via-bosh: BOSH client connections from node.js
• node-simple-xmpp: Simpler high-level client layer
• xmpp-server: Reusable XMPP server on top of node-xmpp
• node-xmpp-joap: Jabber Object Access Protocol (XEP-0075) library for node-xmpp
• node-xmpp-serviceadmin: Service Administration (XEP-0133) library for node-xmpp

Design

Inheritance tree and associations:

┌────────────┐1     1┌────────────┐
│ net.Stream ├───────┤ Connection │
└────────────┘       └────────────┘
                           ↑
      ┌────────────┬───────┴───┬────────────┐
      │            │           │            │
┏━━━━━┷━━━━┓ ┏━━━━━┷━━━━━┓ ┌───┴────┐ ┌─────┴─────┐
┃  Client  ┃ ┃ Component ┃ │ Server │ │ C2SStream │
┗━━━━━━━━━━┛ ┗━━━━━━━━━━━┛ └────────┘ └───────────┘
                               ↑            ↑0..*
         ┌─────────────────────┤            │accepts
         │                     │            │1
┌────────┴───────┐ ┌───────────┴────┐ ┏━━━━━┷━━━━━┓
│ OutgoingServer │ │ IncomingServer │ ┃ C2SServer ┃
└─────────────┬──┘ └───┬────────────┘ ┗━━━━━┯━━━━━┛
         0..* │        │ 0..*               │
      creates │        │ accepts            │
             ┏┷━━━━━━━━┷┓                   │
             ┃  Router  ┃←──────────────────┘
             ┗━━━━━━━━━━┛ 1

This foundation is complemented by two basic data structures:

• JID: a Jabber-Id, represented as a triple of user, domain, resource
• Element: any XML Element

Building XML Elements

Strophe.js' XML Builder is very convenient for producing XMPP stanzas. ltx includes it in a much more primitive way: the c(), cnode() and t() methods can be called on any Element object, returning the new child element.

This can be confusing: in the end, you will hold the last-added child until you use up(), a getter for the parent. Connection.send() first invokes tree() to retrieve the uppermost parent, the XMPP stanza, before sending it out the wire.