SYS-CON MEDIA Authors: Xenia von Wedel, Peter Silva, Glenn Rossman, Ava Smith, Elizabeth White

Related Topics: Java

Java: Article

Building a J2ME Multimedia Messaging Service Client

Host your own MMS content server and more

The Wireless Messaging API (WMA) reference implementation supports short message service (SMS) text and binary messages, but leaves the implementation of the hot area of multimedia messaging untouched. This article will demonstrate how to build a Multimedia Messaging Service (MMS) client using J2ME so you can get started writing new applications using this technology. By doing your own J2ME client implementation, you can bypass carrier lock-in of the content server or Multimedia Messaging Service Center (MMSC), as well as build your own server-side MMS applications, which you couldn't do before outside of the carrier network.

Software Requirements
A number of software requirements are needed to test the MMS client application. To run the basic emulation environment, make sure you have Sun's Wireless Toolkit 2.1 and JDK 1.4.2 or higher, both downloadable at http://java.sun.com. Download and compile the latest source code for the MMS Client and tools, available at http://sourceforge.net/projects/jvending. Next, set up either a Web or application server to act as the content server for the multimedia messages. Finally, you'll need to download the Nokia Mobile Internet Toolkit 4.0 from www.forum.nokia.com.

MMS Notification and Retrieval
The push registry maintains a list of inbound connections to mobile devices. It's one of the most exciting and least used features of the MIDP 2.0 spec. Under MIDP 1.0, a network-based application needed to constantly establish a connection and poll an application server for events. This ate up airtime and cost the user money, making network-based J2ME applications infeasible in many cases.

You can register inbound connections in the push registry by adding the connection information to the JAD file or by explicitly invoking the registerConnection static method on the PushRegistry class. In the J2SE world, registration is equivalent to opening a ServerSocket connection and waiting for a connection. The snippet below shows how we can register the connections in the JAD.

MIDlet-Push-1: serversocket://:1236, org.jvending.messaging.mmclient.MmsMidlet, *
MIDlet-Push-2: datagram://:1235, org.jvending.messaging.mmclient.MmsMidlet, *
MIDlet-Push-3: sms://:1234, org.jvending.messaging.mmclient.MmsMidlet, *

Why would you need to register so many push connections? There are a number of different ways to push the message notification, depending on the carrier network. You may need to set up push interfaces to cover push-over TCP (serversocket), WDP/UDP (datagram), and SMS. For instance, if we have an active GPRS or CSD connection, the server application may decide to send the MMS notification on the datagram connection, without failing over to the SMS connection. This means our MMS message is effectively lost.

Let's show how notification works in a carrier environment. Prior to the recipient MMS user agent retrieving an MMS message, the network must notify the user agent that the message is awaiting retrieval. There are a number of different ways for this notification to take place. The most common are SMS or WDP/UDP. If the user does not have a data session established, the notification will come over an SMS bearer. If a session has been established, the server just needs to push the request to the device over WDP/UDP (WAP 1.2+) or TCP (WAP 2.0).

Figure 1 shows a typical configuration within a carrier network for connectionless (asynchronous) notification through SMS. In step 1, the MMSC contacts the Push Proxy Gateway (PPG), which handles the pushing of messages to the mobile device. Next, the PPG contacts the Short Message Service Center (SMSC). In steps 3 and 4, the SMS is delivered over the GPRS network to the mobile device. If the MIDlet is not active, the application management software (AMS) detects that an SMS is destined, say, for port 1234. The AMS starts an instance of MmsMidlet, which extracts the MMS notification message from the body of the SMS message to find the MMS content location. In step 5, our application on the mobile device initiates an HTTP/GET connection to the content server.

Keep in mind that in most networks the connection is over the Wireless Session Protocol (WSP), which has an encoding that the content server does not understand. For steps 6 and 7, the network routes the HTTP request to the WAP gateway. The WAP gateway translates the WSP binary encoded HTTP headers into normal HTTP headers and forwards the request (step 8) onto the content server. The content server now delivers the WSP encapsulated MMS message over HTTP back to the mobile device. The MmsMidlet receives the MMS message, decodes it, and displays the graphical content to the user.

Testing Message Notification and Retrieval over an SMS Bearer
Let's test out retrieving an MMS message. First we need to set up a content server, which is merely an application or Web server that stores the MMS content. You can find sample MMS files in the Nokia Mobile Toolkit. Place marketupdate.nosmil.mms on the application server at, say, http://localhost:8080/ ROOT/marketupdate.nos mil.mms.

Now we need to generate an MMS message notification package. Do this by instantiating the org.jvending.tools .mms.MNotificationGenerator class, with parameters filename and content URL location (http://localhost:8080/ ROOT/marketupdate.nosmil.mms), which points to the location of the MMS message on the content server. You now have an MMS notification message stored on your local file system.

Next, open the WMA console within the Wireless Toolkit utilities tool. Make sure you're using version 2.1, since version 2.0 has a problem binary encoding characters within the 128-159 range. Click the "Send SMS" button followed by the Binary SMS tab. Import the contents of the MMS message that you generated with the MNotificationGenerator and type in port number 1234 within the text field.

Open up the emulator and click the MmsMidlet. You'll get a message asking if it's okay to receive text (or SMS) messages. Click OK. Go back to the WMA console and click "Send". This sends the binary SMS that contains the MMS notification to the recipient MMS user agent. Look at the package structure in Figure 2; the SMS body contains the MMS headers.

The MMS client application decodes this message and determines that it is an MMS notification message. The client reads the content URL location, opens an HTTP connection to the content server, pulls down the MMS message containing the mymessage.mms (see Figure 3), and displays the content on the mobile device. I'll explain exactly how to do this in the next sections.

Decoding the Multimedia Message
The MultimediaParser instance has a parse method that takes a PeekInputStream instance and a multimedia message object as parameters. A multimedia message object consists of two primary parts: the MMS headers and the MIME body (see Figure 3). The MultimediaParser instance delegates construction of the multimedia message object to two other objects, the HeaderFieldParser and the MimeParser.

The HeaderFieldParser's primary responsibility is to hand off the PeekInputStream object to an instance of WspTokenizer, which tokenizes the input stream into header fields according to the WSP spec. WSP encoding is a compact binary form that reduces the size of the headers.

The way this works is that if the first octet (or byte) is in the range of 32-127, the header is a text string, which ends with a 0 or null octet. If the first octet is in the range of 128-255, the header is binary encoded. For instance, if the value is 151, this maps to a TO field, which is subsequently followed by an encoded string. The less common values that begin in the range 0-31 are of variable length and center largely around date values.

This type of encoding makes tokenizing of the multimedia messaging surprisingly simple. You can decompose MMS into one of the following tokens: Text-String, Quoted-String, Extension-media, Short-integer, Multi-octet-integer, and Unitvar-Integer. The last two are integers of variable length, not something we have to deal with very often within the Java world. Essentially, they are just 128 base numbers and can be handled accordingly. See the source code to see how to encode/decode multi-octets. (The source code can be downloaded from www.sys-con.com/java/sourcec.cfm.)

With the exception of octets in the range of 0-31, the WspTokenizer object can determine the exact token and how to read the header based on the first octet. If the value is less than 32, however, the tokenizer peeks ahead one octet to determine the path that it needs to tokenize the header (see Listing 1).

After tokenization, the HeaderFieldParser object passes those tokens to an instance of the HeaderFieldAssembler, which takes the tokens and assembles them into easily readable Field objects to store within the target MultimediaMessage object.

Now that the HeaderFieldParser object has finished decoding the MMS headers, the MultimediaParser passes control to an instance of MimeParser, provided that the message contains a Content-Type field. The MimeParser object now assembles the MultipartEntry objects for the various MIME types and places them within the instance of MultimediaMessage. Our target MultimediaMessage object is now complete and ready to pass to the MessageConnection object, covered in the next section.

Extending the Wireless Message API
The wireless message API consists of five interfaces:

  1. BinaryMessage
  2. Message
  3. MessageConnection
  4. MessageListener
  5. TextMessage
The BinaryMessage and TextMessage classes extend the Message interface. For this article, we add an additional class, MultimediaMessage, which also extends the message interface.

The javax.wireless.messaging. MessageConnection class has its own implementation on the mobile devices. Modifying this implementation to return MultimediaMessage objects would require recompiling core MIDP 2.0 classes. Thus, the MMS client has its own implementation called org.jvending.messaging.MessageConnection, which functions in the same way with the same API. Look at the receive method of org.jvending.messaging.MessageConnection. This implementation accepts two kinds of connections: HTTP and SMS, both of which return a Message object of type MultimediaMessage.

If the URL connection is HTTP based, invoking the receive method on the MessageConnection instance results in the mobile device initiating an HTTP connection to the content server and pulling down an MMS message. The MessageConnection object casts the connection as an HttpConnection and invokes the openInputStream method to obtain an InputStream object. This does not involve the WMA messaging functionality

If the connection is SMS, we leverage the WMA by casting the connection as javax.wireless.messaging.MessageConnection and receiving a BinaryMessage. We now need to get it into an InputStream object since this type is required to pass into the instance of MultimediaParser. This requires invoking the getPayloadData() method on the BinaryMessage and feeding this in as a parameter to an instance of ByteArrayInputStream.

Finally, the MessageConnection object creates an instance of PeekInputStream and then invokes the parse method on the MultimediaParser object. The target MultimediaMessage object is now filled with all the MMS headers and MIME entries. Note that the MessageConnection is not concerned with the type of MMS message or how to handle notification and retrieval flow. The MmsMidlet client handles this logic (see Listing 2).

The MMS Client
The org.jvending.messaging. mmsclient package contains two classes: the MmsMidlet, which contains the logic for instantiating MessageConnection classes; and the MultimediaViewer class, which handles the display of the headers and media types. The first thing the MmsMidlet does is open an SMS connection and then wait to receive a MultimediaMessage on port 1234 (of course, in the actual source code this is threaded).

When the MMS notification comes over the SMS bearer, the MmsMidlet strips out the body and confirms that it is an M_NOTIFICATION message type. The MmsMidlet object takes the content URL location from the MMS notification and uses it as a parameter when invoking the open method on the Connector class. As discussed in the previous section, invoking the receive method on the MessageConnection returns a MultimediaMessage object containing the MIME entries. Next the MmsMidlet passes the MultimediaObject to an instance of MultimediaViewer that will, in turn, display the media content on the user's device (see Listing 3).

Conclusion
In the wireless data area, innovation and development are often difficult because carriers tightly couple device applications and server-side services. When you use J2ME and J2EE together to build client and server applications, it enables you to bypass many of these constraints. All it takes is access to basic SMS and HTTP protocols.

This article illustrates this flexibility by showing how building a J2ME MMS client allows developers to host their own MMS content server. This article also covers the basics of MMS retrieval and notification. The source code contains an MMS encoder that allows the user to send MMS messages. When combined with the Mobile Media API (JSR 135), this provides the ability to create a lot of interesting applications. You can find the latest updates and complete source code at http://sourceforge.net/projects/jvending.

Resources

  • Le Bodic, G. (2003). Mobile Messaging Technologies and Services. Wiley.
  • Metsker, S.J. (2001). Building Parsers with Java. Addison-Wesley.
  • now.sms: www.nowsms.com/messages/index.htm
  • Open Mobile Alliance, OMA-MMS-ENC-v1_1-20021030-C: Multimedia Messaging Service Encapsulation Protocol version 1.1, October 2002.
  • WAP Forum, WAP-230-WSP: Wireless Application Protocol, Wireless Session Protocol Specification Version 5, July 2001
  • More Stories By Shane Isbell

    Shane Isbell works as a software architect at a wireless carrier.

    Comments (0)

    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.


    Latest Stories
    The definition of IoT is not new, in fact it’s been around for over a decade. What has changed is the public's awareness that the technology we use on a daily basis has caught up on the vision of an always on, always connected world. If you look into the details of what comprises the IoT, you’ll see that it includes everything from cloud computing, Big Data analytics, “Things,” Web communication, applications, network, storage, etc. It is essentially including everything connected online from ha...
    We are all here because we are sold on the transformative promise of The Cloud. But what good is all of this ephemeral, on-demand infrastructure if your usage doesn't actually improve the agility and speed of your business? How must Operations adapt in order to avoid stifling your Cloud initiative? In his session at DevOps Summit, Damon Edwards, co-founder and managing partner of the DTO Solutions, will highlight the successful organizational, process, and tooling patterns of high-performing c...
    Software-driven innovation is becoming a primary approach to how businesses create and deliver new value to customers. A survey of 400 business and IT executives by the IBM Institute for Business Value showed businesses that are more effective at software delivery are also more profitable than their peers nearly 70 percent of the time (1). DevOps provides a way for businesses to remain competitive, applying lean and agile principles to software development to speed the delivery of software that ...
    Docker offers a new, lightweight approach to application portability. Applications are shipped using a common container format and managed with a high-level API. Their processes run within isolated namespaces that abstract the operating environment independently of the distribution, versions, network setup, and other details of this environment. This "containerization" has often been nicknamed "the new virtualization." But containers are more than lightweight virtual machines. Beyond their small...
    The move in recent years to cloud computing services and architectures has added significant pace to the application development and deployment environment. When enterprise IT can spin up large computing instances in just minutes, developers can also design and deploy in small time frames that were unimaginable a few years ago. The consequent move toward lean, agile, and fast development leads to the need for the development and operations sides to work very closely together. Thus, DevOps become...
    Cloud Expo 2014 TV commercials will feature @ThingsExpo, which was launched in June, 2014 at New York City's Javits Center as the largest 'Internet of Things' event in the world.

    ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ --  IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's

    An entirely new security model is needed for the Internet of Things, or is it? Can we save some old and tested controls for this new and different environment? In his session at @ThingsExpo, New York's at the Javits Center, Davi Ottenheimer, EMC Senior Director of Trust, reviewed hands-on lessons with IoT devices and reveal a new risk balance you might not expect. Davi Ottenheimer, EMC Senior Director of Trust, has more than nineteen years' experience managing global security operations and asse...
    The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com...
    Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at Internet of @ThingsExpo, James Kirkland, Chief Ar...
    Leysin American School is an exclusive, private boarding school located in Leysin, Switzerland. Leysin selected an OpenStack-powered, private cloud as a service to manage multiple applications and provide development environments for students across the institution. Seeking to meet rigid data sovereignty and data integrity requirements while offering flexible, on-demand cloud resources to users, Leysin identified OpenStack as the clear choice to round out the school's cloud strategy. Additional...
    Technology is enabling a new approach to collecting and using data. This approach, commonly referred to as the "Internet of Things" (IoT), enables businesses to use real-time data from all sorts of things including machines, devices and sensors to make better decisions, improve customer service, and lower the risk in the creation of new revenue opportunities. In his General Session at Internet of @ThingsExpo, Dave Wagstaff, Vice President and Chief Architect at BSQUARE Corporation, discuss the ...
    The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, a...
    SYS-CON Media announced today that Aruna Ravichandran, VP of Marketing, Application Performance Management and DevOps at CA Technologies, has joined DevOps Journal’s authors. DevOps Journal is focused on this critical enterprise IT topic in the world of cloud computing. DevOps Journal brings valuable information to DevOps professionals who are transforming the way enterprise IT is done. Aruna's inaugural article "Four Essential Cultural Hacks for DevOps Newbies" discusses how to demonstrate the...
    "BSQUARE is in the business of selling software solutions for smart connected devices. It's obvious that IoT has moved from being a technology to being a fundamental part of business, and in the last 18 months people have said let's figure out how to do it and let's put some focus on it, " explained Dave Wagstaff, VP & Chief Architect, at BSQUARE Corporation, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.