Enabling Technologies for Wireless E-Business phần 9 pdf

12 Mobile Services Computing 307

12.5.1 Scenario

A car is parked in a parking lot, and the owner of the car gets off and walks

somewhere. Before he gets off the car, he turns on the alarm system. The owner

carries a cell phone with him, with the phone connected to a wireless alarm system

(WAS) in the car. WAS has sensors that detect whether the car is touched by

someone. If the car is touched, the WAS sends an alert to the owner’s cell phone.

Thereafter, the owner sends a command to the WAS to protect his car from being

stolen. Based on the thief’s reaction, different requests/commands are sent to the

WAS and the WAS gives feedbacks to the thief until the car engine is locked

finally. The WAS works based on not only the owner’s commands, but also

context information, such as the time, thief’s attempt, and resources available.

The complete scenario of the WAS is shown in Fig. 12.2 and is explained as

follows:

• A thief touches a car.

• The detector (sensor) of the car gets the information and sends it to the

owner’s cell phone.

• The owner of the car sends an alert invocation command to the WAS.

• The WAS gives a speech-based alert to the theft, and the volume of

the alert is determined by time: if it is daytime, the volume may be

higher; otherwise, it is lower.

• The thief continues to tamper the car.

• The detector gets the information, sends it to the owner’s cell phone,

and prompts that the alert does not take effect.

• The owner sends a picture-taking alert command to the WAS.

• The WAS sends a speech-based alert that a picture will be taken if the

theft continues.

• The thief still continues to tamper the car.

• The detector gets the information, sends it to the owner’s cell phone,

and prompts that the taking-picture alert did not take effect.

• The owner sends a picture-taking command to the WAS.

• The WAS invokes the corresponding service and a picture is taken of

the thief and a speech alert is broadcast; if the disk space is not enough

to save the picture, the resource manager is invoked and virtual

memory is added.

• The thief continues to tamper the car.

• The detector gets the information, sends it to the owner’s cell phone,

and prompts that the picture-taking did not take effect.

• The owner of the car sends a command to the WAS to lock the engine.

• The WAS invokes the service to lock the engine.

• Hopefully the thief leaves the car alone.

• Optionally, the WAS can also connect to police either automatically or

based on the owner’s instruction, at any stage, to report the case.

308 L.-J. Zhang, B. Li, and Y. Song

Fig. 12.2. Scenario of WAS

12.5.2 Solution

The architecture of the WAS is shown in Fig. 12.3. This is an example of a

typical context-sensitive mobile service. Four services are available in the WAS,

namely detector service, context service, alert service, and camera service. Since

media data (pictures) must be saved, a resource manager is designed in case that

there is no adequate disk space. It is also possible that different types of cell

phones are used in the WAS so that a device moderator is designed to support

communications between cell phones and mobile devices.

In this implementation, the service is provided by a small device that is

connected to the car. In general, HTTP protocol is not supported by it. So a

specific communication protocol must be used, for example, 802.11. In addition,

the cell phone might be connected to the Internet by GPRS. Therefore, a

multimodal adaptation is required. The cell phone must have the capability to

detect location and the current time, since this information is the context that

supports the mobile service. In summary, each mobile device satisfies the basic

requirements of mobile services, i.e., multimodal adaptor, context adaptor, and

context information collector are included in each of them.

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Fig. 12.3. The architecture of WAS

12.6 Summary

Web service is an effective technique for improving business efficiency by

automating the collaboration of heterogeneous information systems. Its potential

application in the real world is limitless and has been enthusiastically embraced by

the IT industry. By extending it to the wireless and mobile world, much more

people can be connected to the enormous Web of information and services,

anywhere and anytime. The scope and effectiveness of those information services

will transcend to a new level, where unlimited new business opportunities exist.

Some examples are mobile entertainment, mobile enterprise, and mobile law

enforcement. Particularly, mobile Web service is an important approach for

realizing m-commerce, which is expected to become increasingly popular,

following successful desktop e-commerce. Mobile service is the next direction of

Web service. Unique technical challenges lie ahead, if mobile services are to be as

successful as regular Web services.