Welcome!

Java IoT Authors: Liz McMillan, Elizabeth White, Yeshim Deniz, Carmen Gonzalez, Pat Romanski

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
    NHK, Japan Broadcasting, will feature the upcoming @ThingsExpo Silicon Valley in a special 'Internet of Things' and smart technology documentary that will be filmed on the expo floor between November 3 to 5, 2015, in Santa Clara. NHK is the sole public TV network in Japan equivalent to the BBC in the UK and the largest in Asia with many award-winning science and technology programs. Japanese TV is producing a documentary about IoT and Smart technology and will be covering @ThingsExpo Silicon Val...
    The Internet of Things is clearly many things: data collection and analytics, wearables, Smart Grids and Smart Cities, the Industrial Internet, and more. Cool platforms like Arduino, Raspberry Pi, Intel's Galileo and Edison, and a diverse world of sensors are making the IoT a great toy box for developers in all these areas. In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists discussed what things are the most important, which will have the most profound e...
    Multiple data types are pouring into IoT deployments. Data is coming in small packages as well as enormous files and data streams of many sizes. Widespread use of mobile devices adds to the total. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the tools and environments that are being put to use in IoT deployments, as well as the team skills a modern enterprise IT shop needs to keep things running, get a handle on all this data, and deli...
    With billions of sensors deployed worldwide, the amount of machine-generated data will soon exceed what our networks can handle. But consumers and businesses will expect seamless experiences and real-time responsiveness. What does this mean for IoT devices and the infrastructure that supports them? More of the data will need to be handled at - or closer to - the devices themselves.
    SYS-CON Events announced today that Grape Up will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct. 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Grape Up is a software company specializing in cloud native application development and professional services related to Cloud Foundry PaaS. With five expert teams that operate in various sectors of the market across the U.S. and Europe, Grape Up works with a variety of customers from emergi...
    @ThingsExpo has been named the Most Influential ‘Smart Cities - IIoT' Account and @BigDataExpo has been named fourteenth by Right Relevance (RR), which provides curated information and intelligence on approximately 50,000 topics. In addition, Right Relevance provides an Insights offering that combines the above Topics and Influencers information with real time conversations to provide actionable intelligence with visualizations to enable decision making. The Insights service is applicable to eve...
    DevOps is often described as a combination of technology and culture. Without both, DevOps isn't complete. However, applying the culture to outdated technology is a recipe for disaster; as response times grow and connections between teams are delayed by technology, the culture will die. A Nutanix Enterprise Cloud has many benefits that provide the needed base for a true DevOps paradigm.
    Bert Loomis was a visionary. This general session will highlight how Bert Loomis and people like him inspire us to build great things with small inventions. In their general session at 19th Cloud Expo, Harold Hannon, Architect at IBM Bluemix, and Michael O'Neill, Strategic Business Development at Nvidia, discussed the accelerating pace of AI development and how IBM Cloud and NVIDIA are partnering to bring AI capabilities to "every day," on-demand. They also reviewed two "free infrastructure" pr...
    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 ...
    NHK, Japan Broadcasting, will feature the upcoming @ThingsExpo Silicon Valley in a special 'Internet of Things' and smart technology documentary that will be filmed on the expo floor between November 3 to 5, 2015, in Santa Clara. NHK is the sole public TV network in Japan equivalent to the BBC in the UK and the largest in Asia with many award-winning science and technology programs. Japanese TV is producing a documentary about IoT and Smart technology and will be covering @ThingsExpo Silicon Val...
    New competitors, disruptive technologies, and growing expectations are pushing every business to both adopt and deliver new digital services. This ‘Digital Transformation’ demands rapid delivery and continuous iteration of new competitive services via multiple channels, which in turn demands new service delivery techniques – including DevOps. In this power panel at @DevOpsSummit 20th Cloud Expo, moderated by DevOps Conference Co-Chair Andi Mann, panelists will examine how DevOps helps to meet th...
    Five years ago development was seen as a dead-end career, now it’s anything but – with an explosion in mobile and IoT initiatives increasing the demand for skilled engineers. But apart from having a ready supply of great coders, what constitutes true ‘DevOps Royalty’? It’ll be the ability to craft resilient architectures, supportability, security everywhere across the software lifecycle. In his keynote at @DevOpsSummit at 20th Cloud Expo, Jeffrey Scheaffer, GM and SVP, Continuous Delivery Busine...
    SYS-CON Events announced today that Hitachi, the leading provider the Internet of Things and Digital Transformation, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Hitachi Data Systems, a wholly owned subsidiary of Hitachi, Ltd., offers an integrated portfolio of services and solutions that enable digital transformation through enhanced data management, governance, mobility and analytics. We help globa...
    SYS-CON Events announced today that T-Mobile will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. As America's Un-carrier, T-Mobile US, Inc., is redefining the way consumers and businesses buy wireless services through leading product and service innovation. The Company's advanced nationwide 4G LTE network delivers outstanding wireless experiences to 67.4 million customers who are unwilling to compromise on ...
    With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo 2016 in New York. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place June 6-8, 2017, at the Javits Center in New York City, New York, is co-located with 20th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry p...
    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.
    SYS-CON Events announced today that SoftLayer, an IBM Company, has been named “Gold Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York, New York. SoftLayer, an IBM Company, provides cloud infrastructure as a service from a growing number of data centers and network points of presence around the world. SoftLayer’s customers range from Web startups to global enterprises.
    With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend @CloudExpo | @ThingsExpo, June 6-8, 2017, at the Javits Center in New York City, NY and October 31 - November 2, 2017, Santa Clara Convention Center, CA. Learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
    SYS-CON Events announced today that Hitachi Data Systems, a wholly owned subsidiary of Hitachi LTD., will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City. Hitachi Data Systems (HDS) will be featuring the Hitachi Content Platform (HCP) portfolio. This is the industry’s only offering that allows organizations to bring together object storage, file sync and share, cloud storage gateways, and sophisticated search an...
    Most technology leaders, contemporary and from the hardware era, are reshaping their businesses to do software in the hope of capturing value in IoT. Although IoT is relatively new in the market, it has already gone through many promotional terms such as IoE, IoX, SDX, Edge/Fog, Mist Compute, etc. Ultimately, irrespective of the name, it is about deriving value from independent software assets participating in an ecosystem as one comprehensive solution.