Welcome!

Java IoT Authors: Liz McMillan, Elizabeth White, Carmen Gonzalez, Mano Marks, Jyoti Bansal

Related Topics: Java IoT

Java IoT: Article

Building an Instant Messaging Application Using Jabber/XMPP

An adventure with Smack and Wildfire

This article will describe our experiences with developing a Java-based instant messenger application using Jabber/XMPP (Extensible Messaging and Presence Protocol) - a free, open and public protocol and technology for instant messaging. According to the Jabber Software Foundation, "Under the hood, Jabber is a set of streaming XML protocols and technologies that enable any two entities on the Internet to exchange messages, presence, and other structured information in close to real-time."

Google Talk uses the standard Jabber/XMPP protocol for authenticating, presence, and messaging. But using Jabber goes beyond instant messaging to almost real-time server-to-server communication.

This article will describe the Jabber/XMPP protocol for messaging, the Jabber/XMPP client program based on JFace and Eclipse, and the Jabber/XMPP Java server. These will be illustrated through Open Source Smack and the Wildfire Server 2.4.4. It will offer examples of a login-class plug-in for custom authentication, a plug-in and server extension for custom messages, and a server-side extension for database interactions. Each example will contain the XML messages, client-side code, and server-side code.

What's Different About Jabber?
Compared to traditional IM programs, Jabber:

  1. Is an XML-based messaging protocol that is open and extensible
  2. It lets you build custom client IM applications. We'll talk about Smack, a project based on JFace and Eclipse that provides tools for building custom client applications
  3. It lets you extend the functionality of the server to process custom messages by writing server-side plug-ins. We'll describe the plug-in architecture of the Wildfire Server
What Are the Basic Features of Instant Messaging?
Any instant messaging system will have these basic features: It connects to server, registers new users, logs in, gets presence information, exchanges messages, and does custom interactions (VoIP, Web conferencing, etc.). Below each of these IM features are described using XMPP:

  • Connect to Server - This is done through a XML stream header exchange. The client sends:

    <stream to='192.168.0.12:5222' xmlns='jabber:client'/>

    The client receives:

    <stream id='xxxx' from:'192.168.0.12:5222' xmlns='jabber:
    client'/>

  • Register - The client sends a message to discover the server's requirements for registration:

    <iq type='get' id='reg1' to='192.168.0.12:5222'><query xmlns='jabber:iq:register'/></iq>

    The server responds with a message that lists the fields required for registration:

    <iq type='result' id='reg1'> <query xmlns='jabber:iq:register'>
          <instructions>

    Choose a username and password for use with this service.
    Please also provide your email address.        </instructions>
         <username/>
         <password/>
         <email/>
       </query></iq>

    The client responds by sending the requested information:

    <iq type='set' id='reg2'>
       <query xmlns='jabber:iq:register'>
         <username>a3</username>
         <password>password</password>
         <email>[email protected]</email>
       </query>
    </iq>

    On successful registration, the server responds:

    <iq type='result' id='reg2'/>

    Declare Presence and Get Presence Information
    To declare presence information, the client sends:

    <presence xmlns="" id="d6vNV-3" from="[email protected]/1139352545625"/>

    Note the "to" attribute isn't required in the above message because the client knows which server it's talking to.

    To get presence information, client sends:

    <iq xmlns="" id="d6vNV-2" type="get" from="[email protected]/1139352545625">
    <query xmlns="jabber:iq:roster"/>
    </iq>

    The server responds with presence data about two people in the roster:

    <iq xmlns="" type="result" id="d6vNV-2" to="[email protected]/1139352545625">
       <query xmlns="jabber:iq:roster">
          <item jid="[email protected]" name="Jorge" subscription="both"></item>
          <item jid="[email protected]" name="Dr. Bruce" subscription="both"></item>
       </query></iq>

    Exchange Messages
    User a1 sends message to user a2:

    <message xmlns="" id="H49LH-12" to="[email protected]" type="chat" from="a2 @sow/1139385809707">
         <body>Good Morning, I am testing chat in Jabber Client.</body>
    </message>

    The elements above form the core of XMPP (Extensible Messaging and Presence Protocol) XML syntax. It also gives you a sense of the flow of XML messages between the client and server to accomplish a task.

    Jabber/XMPP Client and Server
    Since Jabber/XMPP is an open protocol scores of implementations have been created for the client and server, some Open Source and others commercial. There are literally hundreds of Jabber clients available. (See References.)

    In this article we'll use the Smack library (www.jivesoftware.org/smack/) to illustrate client-side functionality. Smack provides an API for implementing the GUI and managing XML data. Managing XML data involves creating XML messages, sending the messages, receiving messages from the server, and processing the incoming messages.

    We'll use the Wildfire Server (www.jivesoftware.org/wildfire/) for illustrating creating server-side plug-ins. For basic IM needs, no server-side programming is required. For other needs Wildfire provides a plug-in architecture for extending the server's functionality. We'll look next at a use case to illustrate how custom messages can be created and processed at both the client and server.

    Use Case 1: Custom Authentication and Custom Queries
    Consider a case in which an IM client and a Web portal are part of a suite of collaboration applications. The Web portal has database-driven MD5-based authentication and the requirement is that IM client use the portal's authentication service. This will allow users to log in to IM and then launch applications on the portal from the IM client without logging into the portal.

    Part A: Custom Authentication
    The Wildfire Server uses the DefaultAuthProvider class to authenticate users and DefaultUserProvider to get user information. These use the database tables Wildfire provides.

    If you want to use a custom authentication method you'll have to change the user and authentication provider in wildfire.xml.

    <provider>
    <user> <className>org.indent.wildfire.user.SOWUserProvider</className> </user>
    <auth><className>org.indent.wildfire.auth.SOWAuthProvider</className> </auth>
    </provider>

    The simple extension defined in Listing 1 uses custom tables and custom encryption methods. The SOWUserProvider class is for user info and SOWAuthProvider is for authentication.

    The two static variables shown define the database authentication strings. And if custom encryption is used then the encryptPassword() method provides the encryption logic.

    Part B: Retrieving a Token from the Database
    In this use case, after authenticating, the client is going to ask the database for an encrypted token that uniquely identifies the client. This token is later used to launch applications in the Web portal without explicitly logging into the portal. The steps are:
    a)  The client generates a custom message to request a token
    b)  The server gets the message and processes the request by getting a token from the database. The server generates a reply message that contains the token and sends it to the requesting client
    c)  The client gets the message and extracts the token

    This process is illustrated in Figure 1.

    Client to Server
    The client generates a <iq> packet that looks like:

    <iq to="serverName" type="get"><query xmlns="jabber:iq:token"/></iq>

    jabber:iq:token is a namespace for our custom query. This message is generated at the client using the following code:

           XMPPConnection connection = session.getConnection();
           ClientID packet = new ClientID();
           connection.sendPacket(packet);

    The Class ClientID is defined in the section "Client-side Processing of Reply Packets" below.

    The Server-Side Plug-In
    The first step is to create a plug-in that will process the custom message with xmlns="jabber:iq:token." The plug-in is called ClientTokenPlugin. It first creates an IQTokenHandler; the handler is then added to the iq router that routes all the incoming iq messages:

    public class ClientTokenPlugin implements Plugin {
        public ClientTokenPlugin() {
           IQHandler iqRDHandler = new IQTokenHandler();
           IQRouter iqRouter = XMPPServer.getInstance().getIQRouter();
           iqRouter.addHandler(iqRDHandler);
        }
        public void initializePlugin(PluginManager manager, File pluginDirectory) { }
        public void destroyPlugin() { }
    }

    For more on how to create a plug-in, see www.jivesoftware.org/builds/wildfire/docs/ latest/documentation/plugin-dev-guide.html.

    IQTokenHandler has two key methods:

    a)  getInfo() which returns the type of queries in the iq messages that the token handler is going to process
    b)  handleIQ() which processes the incoming message/packet and creates a reply message/packet

    public class IQTokenHandler extends IQHandler {
       public IQTokenHandler() { super("Client Token Handler"); }
       public IQHandlerInfo getInfo() {
         return new IQHandlerInfo("query","jabber:iq:token"); }

       public IQ handleIQ(IQ packet) {
       IQ replyPacket = IQ.createResultIQ(packet);
       Element m = replyPacket.setChildElement("query", "jabber:iq:token");
    // 2 lines below are specific to our needs; change them to get data according to your needs
       ClientSession session = sessionManager.getSession(packet.getFrom());
       String token = (String)UserTokenList.get(JID.unescapeNode(session.getAddress().getNode().toLowerCase()));
       m.addElement("tokenNum").addText(token);
       return replyPacket;
       }
    }

    The reply message will look like:

    <iq to="clientName">
       <query xmlns="jabber:iq:token">
         <tokenNum>abcdefgh</tokenNum>
       </query></iq>


  • More Stories By Pramod Jain

    Pramod Jain is president of Innovative Decision Technologies, Inc. (INDENT, www.indent.org), in Jacksonville, FL. Their clients include Recruitmax, NASA, and NIH. Pramod has a PhD from the University of California, Berkeley.

    More Stories By Mahaveer Jain

    Mahaveer Jain is a lead programmer at INDENT. His expertise is in developing collaboration applications with Java technologies.

    Comments (2) View Comments

    Share your thoughts on this story.

    Add your comment
    You must be signed in to add a comment. Sign-in | Register

    In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


    Most Recent Comments
    SYS-CON Australia News Desk 06/23/06 09:05:30 AM EDT

    This article will describe our experiences with developing a Java-based instant messenger application using Jabber/XMPP (Extensible Messaging and Presence Protocol) - a free, open and public protocol and technology for instant messaging. According to the Jabber Software Foundation, 'Under the hood, Jabber is a set of streaming XML protocols and technologies that enable any two entities on the Internet to exchange messages, presence, and other structured information in close to real-time.'

    SYS-CON Australia News Desk 06/22/06 03:52:45 PM EDT

    This article will describe our experiences with developing a Java-based instant messenger application using Jabber/XMPP (Extensible Messaging and Presence Protocol) - a free, open and public protocol and technology for instant messaging. According to the Jabber Software Foundation, 'Under the hood, Jabber is a set of streaming XML protocols and technologies that enable any two entities on the Internet to exchange messages, presence, and other structured information in close to real-time.'

    @ThingsExpo Stories
    "LinearHub provides smart video conferencing, which is the Roundee service, and we archive all the video conferences and we also provide the transcript," stated Sunghyuk Kim, CEO of LinearHub, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
    Internet of @ThingsExpo, taking place June 6-8, 2017 at the Javits Center in New York City, New York, is co-located with the 20th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. @ThingsExpo New York Call for Papers is now open.
    The 20th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held June 6-8, 2017, at the Javits Center in New York City, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Containers, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportunity. Submit your speaking proposal ...
    "There's a growing demand from users for things to be faster. When you think about all the transactions or interactions users will have with your product and everything that is between those transactions and interactions - what drives us at Catchpoint Systems is the idea to measure that and to analyze it," explained Leo Vasiliou, Director of Web Performance Engineering at Catchpoint Systems, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York Ci...
    WebRTC is the future of browser-to-browser communications, and continues to make inroads into the traditional, difficult, plug-in web communications world. The 6th WebRTC Summit continues our tradition of delivering the latest and greatest presentations within the world of WebRTC. Topics include voice calling, video chat, P2P file sharing, and use cases that have already leveraged the power and convenience of WebRTC.
    20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
    Discover top technologies and tools all under one roof at April 24–28, 2017, at the Westin San Diego in San Diego, CA. Explore the Mobile Dev + Test and IoT Dev + Test Expo and enjoy all of these unique opportunities: The latest solutions, technologies, and tools in mobile or IoT software development and testing. Meet one-on-one with representatives from some of today's most innovative organizations
    DevOps is being widely accepted (if not fully adopted) as essential in enterprise IT. But as Enterprise DevOps gains maturity, expands scope, and increases velocity, the need for data-driven decisions across teams becomes more acute. DevOps teams in any modern business must wrangle the ‘digital exhaust’ from the delivery toolchain, "pervasive" and "cognitive" computing, APIs and services, mobile devices and applications, the Internet of Things, and now even blockchain. In this power panel at @...
    Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, discussed the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
    The WebRTC Summit New York, to be held June 6-8, 2017, at the Javits Center in New York City, NY, announces that its Call for Papers is now open. Topics include all aspects of improving IT delivery by eliminating waste through automated business models leveraging cloud technologies. WebRTC Summit is co-located with 20th International Cloud Expo and @ThingsExpo. WebRTC is the future of browser-to-browser communications, and continues to make inroads into the traditional, difficult, plug-in web co...
    "A lot of times people will come to us and have a very diverse set of requirements or very customized need and we'll help them to implement it in a fashion that you can't just buy off of the shelf," explained Nick Rose, CTO of Enzu, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
    In 2014, Amazon announced a new form of compute called Lambda. We didn't know it at the time, but this represented a fundamental shift in what we expect from cloud computing. Now, all of the major cloud computing vendors want to take part in this disruptive technology. In his session at 20th Cloud Expo, John Jelinek IV, a web developer at Linux Academy, will discuss why major players like AWS, Microsoft Azure, IBM Bluemix, and Google Cloud Platform are all trying to sidestep VMs and containers...
    Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud enviro...
    SYS-CON Events announced today that MobiDev, a client-oriented software development company, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place June 6-8, 2017, at the Javits Center in New York City, NY, and the 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MobiDev is a software company that develops and delivers turn-key mobile apps, websites, web services, and complex softw...
    WebRTC is about the data channel as much as about video and audio conferencing. However, basically all commercial WebRTC applications have been built with a focus on audio and video. The handling of “data” has been limited to text chat and file download – all other data sharing seems to end with screensharing. What is holding back a more intensive use of peer-to-peer data? In her session at @ThingsExpo, Dr Silvia Pfeiffer, WebRTC Applications Team Lead at National ICT Australia, looked at differ...
    Fact is, enterprises have significant legacy voice infrastructure that’s costly to replace with pure IP solutions. How can we bring this analog infrastructure into our shiny new cloud applications? There are proven methods to bind both legacy voice applications and traditional PSTN audio into cloud-based applications and services at a carrier scale. Some of the most successful implementations leverage WebRTC, WebSockets, SIP and other open source technologies. In his session at @ThingsExpo, Da...
    Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Day 2 Keynote at 17th Cloud Expo, Sandy Ca...
    SYS-CON Media announced today that @WebRTCSummit Blog, the largest WebRTC resource in the world, has been launched. @WebRTCSummit Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @WebRTCSummit Blog can be bookmarked ▸ Here @WebRTCSummit conference site can be bookmarked ▸ Here
    Manufacturers are embracing the Industrial Internet the same way consumers are leveraging Fitbits – to improve overall health and wellness. Both can provide consistent measurement, visibility, and suggest performance improvements customized to help reach goals. Fitbit users can view real-time data and make adjustments to increase their activity. In his session at @ThingsExpo, Mark Bernardo Professional Services Leader, Americas, at GE Digital, discussed how leveraging the Industrial Internet and...
    Who are you? How do you introduce yourself? Do you use a name, or do you greet a friend by the last four digits of his social security number? Assuming you don’t, why are we content to associate our identity with 10 random digits assigned by our phone company? Identity is an issue that affects everyone, but as individuals we don’t spend a lot of time thinking about it. In his session at @ThingsExpo, Ben Klang, Founder & President of Mojo Lingo, discussed the impact of technology on identity. Sho...