Professional JMS
Overview
The emergence of mobile devices and packet-oriented wireless bearers is generating a new mass market that is expected to surpass one billion users this decade. The new Wireless Net, connecting mobile devices using wireless bearers, promises exciting new opportunities.
After analysing problems and requirements of next-generation wireless services, we will conclude that JMS, when implemented correctly, offers an ideal middleware solution for such services.
The chapter is structured as follows:
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We'll first look at current market trends in the mobile messaging world
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We'll give an overview of current-generation and next-generation wireless bearers
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We'll then describe the mobile device platforms that are being considered for the new generation of mobile phones and communicators, namely Symbian, Palm OS, and Windows CE
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We'll cover some of the technical issues facing mobile applications
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By taking those issues as a starting point, we'll derive some requirements for mobile applications middleware
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We'll show how JMS can be used for developing wireless applications that are interactive and able to deliver richer content to the user
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Finally, we'll give example applications enabled by mobile JMS technology
First of all, however, let's make sure we are on the same page with some definitions of the different technologies in this area.
Terminology
The growth of the mobile applications industry has given rise to a vocabulary of new acronyms and terms, some of which will be familiar, and some not. In this preliminary section we present the main terms used in this chapter for quick reference:
| Acronym | Expansion | Description |
|---|---|---|
| GSM | Global System for Mobile Communication | A mobile telephone system widely used in Europe |
| SMS | Short Message Service | A service for sending messages of up to 160 characters to mobile phones that use GSM |
| AMPS | Advanced Mobile Phone Service | A mobile telephone system widely used in the United States |
| GPRS | General Packet Radio Service | A packet-based wireless bearer based on the GSM standard |
| EDGE | Enhanced Data Rates for Global Evolution | A packet-based wireless bearer based on the GSM standard |
| UMTS | Universal Mobile Telecommunications System | A third-generation wireless bearer |
| i-mode | - | A mobile telephone system widely used in the United States |
| WAP | Wireless Application Protocol | A standard to enable users to access Internet services via their cellular phones |
| GPS | Global Positioning System | GPS-enabled devices are able to compute their geographic location by processing signals received from GPS satellites |
Market Trends
The next few years will be characterized by:
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The appearance of new types of mobile devices or "communicators", unifying the features of cellular phones and PDAs.
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The appearance of packet-oriented wireless bearers, such as GPRS, EDGE, and UMTS. Such bearers allow a communicator to be "always on", meaning always able to receive e-mail notifications and the like, without requiring the user to dial into the network service.
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Communicator devices outnumbering personal computers with Internet access.
The Y-axis in the graph opposite shows worldwide mobile Internet subscribers versus fixed Internet subscribers. The numbers are given in millions. Countries such as Finland already have high Internet and mobile device penetration rates and might reach the crossing point earlier than 2004:
| Note | For further resources in this area, see The Wireless Internet, Nomura Equity Research, September 2000: http://www.nomura.co.uk. |
Fatter Clients
The accepted wisdom today is that communicator devices will run fatter client applications than earlier realized. With microprocessor power on mobile devices increasing more rapidly than wireless bandwidth, and with mobile users demanding applications such as chat, multimedia messaging, and trading, it makes sense to deploy custom software on the mobile device. This will allow the user to display richer content, and to use a mobile application when the mobile device is temporarily disconnected from the network. Java, XML, and messaging middleware will undoubtedly play important roles in the Wireless Net.
Machine-to-Machine Communication
At the moment, wireless communication is still used predominantly for voice calls (80% of the total traffic), but the traffic generated by data services (Internet surfing, SMS) is growing rapidly. Whereas most of the communication is occurring in human-to-human or human-to-machine forms, machine-to-machine communication is expected to become very important on the Wireless Net. The reasons are the following:
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Automobiles, streetcars, vending machines, and other devices are being equipped with powerful CPUs as well as with wireless modems. For example, certain Coca-Cola vending machines allow you to purchase a can by dialing into the machine or by sending an SMS message to it. A can is released immediately and charged to your phone bill.
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Embeddable wireless modems are getting cheaper. For example, the Siemens DECT Engines product line consists of wireless transceivers that can be embedded into consumer products and other devices.
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It is more cost effective to monitor and administer a vending machine remotely than by sending staff into the field. A vending machine can send an alert notification to a service center shortly before running out of supply. The same idea can be applied to the reading of gas-meters, the remote administration of parking meters, and so on.
The following table provides examples of wireless interactions occurring from human to human, human to machine, and machine to machine. A distinction is made whether interactions are voice-enabled or data-driven:
| Type | Voice | Data |
|---|---|---|
| Human-Human | Phone calls, phone conferences | Short messages (SMS), Voice-over-IP |
| Human-Machine | Flight confirmation, phone banking | Web browsing, WAP, i-mode, SMS services (weather, movies, etc.) |
| Machine-Machine | N/A | Remote monitoring, alerting, remote administration, manufacturing control |
In short, today it's normal for people to carry a cellular phone. In the near future, it will become normal for home appliances, vehicles, and parking meters to be wireless-enabled as well.
Location
At the beginning of this chapter, we stated that the combination of mobile devices and packet-oriented wireless bearers enable interesting new applications and services. But there is a third important ingredient, namely location information.
Consider what shopping could be like in two to three years from now. Walking along Sixth Avenue, your communicator beeps. You open it up and activate the Buddies application. This application has a radar-sweep interface, in which you see that one of your friends or relatives is located within 200 yards from you. Now both you and your friend receive an alert notification from the nearby Starbucks, offering you a discount on a tall latt$eA in case you decide to meet at that coffee shop within 30 minutes. You can accept or deny the invitation, or simply enter a private chat session with your friend to figure out whether you want to get together or not.
Location information is likely to play an important role in mobile shopping, wireless advertising, entertainment, anti-theft systems, and so forth. Location information enables an application running on a mobile device to obtain position information about the user of the device (if the user allows this), about other users, or about objects of common interest (museums, galleries, restaurants, etc.).
There are two main techniques for providing location information to mobile applications: putting a GPS (Global Positioning System) module onto the device, or, in case of a mobile phone, using the geographical location of the nearby base stations to compute the location of the mobile device. Many different solutions are being tested today. They typically differ in:
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Accuracy
A high-quality positioning system can provide location information with an accuracy of 10 feet.
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Efficiency
A high-quality positioning system can compute the location of a mobile device in 1 to 2 seconds. However, GPS can incur a substantial computational burden on the mobile device.
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Cost
GPS-based location systems require the presence of a GPS hardware module on the device. The extra cost can be substantial. Positioning systems relying on base station information are often less accurate than GPS, but do not require any special hardware on the device.
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Power Consumption
Positioning solutions differ further in their power consumption. Long battery life is an important acceptance criterion for mobile devices, but a GPS module often consumes substantial battery power.
Whatever technique is used, confidentiality remains a key concern for the user of location-based services. Whoever can track your location information can draw conclusions about your shopping patterns or about other personal habits.
Another issue is the lack of application development standards for accessing location information programmatically. For example, there are no standard APIs for requesting location information in a convenient and portable way. Initially, it is expected that location information will be offered to applications via a wireless-messaging bearer, for instance SMS. In this case, a device sends an SMS message containing a special keyword to a service number. A location service sends back a reply message to the application, containing location information of the device itself, or of another device. Eventually, it is expected that APIs will be established for the Java 2 Platform, Micro Edition (J2ME) as well as for other development environments.