![](bg5.png)
to the mobile device (through the servlet); if the
device is disconnected from the network, the results
are saved in the user’s profile and an SMS message
is sent to the user informing her that the results are
available. This strategy has been implemented in the
MobiAgent [Mahmoud, 2002] system architecture.
Figure 3 shows a snapshot of how it works.
4.3 Personalization
In the responsibility-driven architecture, new
modules can be easily added to be responsible for
tasks such as location-awareness and
personalization. Personalization means that only
relevant information should be downloaded to the
mobile devices and then present that information
effectively taking into account the user’s preferences
and history along with the task at hand. In
personalization, however, data is persistent by nature
and therefore this is different from maintaining
session states where data is transient.
Personalization is important in mobile enterprise
applications; as an example consider a login screen
where the user needs to enter a valid user name and
password in order to use an application. Such screen
login doesn’t change from session to session. Thus,
the user should be asked to enter the login
information only once.
Personalization is not without privacy and
security issues, however. An automatic login feature
is one way to improve the user experience and avoid
tedious authentication procedures. Personalization
may require storing data on the device and therefore
special care should be taken to protect its integrity
and confidentiality. As an example, consider the
case where a piece of sensitive information is stored
on the device. It should be ok to automatically send
the sensitive information to the server but not
display it on the screen. If the user wishes to view
such sensitive information, the operation should
require the user to enter a password. This is
important so that if the device is lost and someone
finds it, the sensitive information cannot be retrieved
out of the device.
4.4 Benefits of the Proposed
Architecture
The benefits of this responsibility-driven
architecture can be summarized as follows: First, it
is simple but yet quite effective and easy to
implement using existing technologies; it enables
multiple mobile clients to access enterprise services;
the architecture is transparent as the client is not
aware of the location of the enterprise services; it
provides anytime, anywhere access to enterprise
services; it is based on open industry standards, such
as HTTP and XML; it promotes loose coupling
between mobile thin-clients and enterprise servers; it
is inherently scalable since it is based on proven
scalable architectures such as Servlets; and finally it
is Web services ready: the latest release of the J2EE
(J2EE 1.4) enables developers to expose existing
J2EE enterprise applications as Web services that
would be ready to be consumed by mobile clients.
5 CONCLUSION
In this paper we have discussed the characteristics of
the wireless environment and the technologies that
are available for developing mobile applications. A
responsibility-driven architecture for mobile
enterprise applications was discussed. This
architecture provides a software infrastructure for
accessing enterprise applications from mobile
clients. The architecture is simple yet effective since
responsibilities are divided among its components;
such division makes it easier to develop, test, and
maintain mobile enterprise applications. The
architecture is scalable and capable of handling
growth since it is based on proven scalable server
solutions such as servlets and EJBs. Our future work
includes extending this architecture with mobile
middleware that will play a crucial role in mobile
enterprise computing and mobile commerce
systems.
REFERENCES
Beaulieu, M., 2002. Wireless Internet Applications and
Architecture. Addison-Wesley.
Burkhardt, J., Henn, H., Hepper, S., Rintdorff, K., 2002.
Pervasive Computing Technology and Architecture of
Mobile Internet Applications. Addison-Wesley.
Mahmoud, Q.H., 2002. An Agent-based Approach to the
Wireless Internet. In Journal of Internet Technology,
Vol. 3, No. 2, pp. 153 – 158.
Sun Microsystems Inc., (J2ME), 2000:
http://java.sun.com/j2me
White, J., 1997. Mobile Agents. In Bradshaw, J.M. (ed.),
Software Agents, AAAI/MIT Press, pp. 437-472.
Wiederhold, G., 1992. Mediators in the Architecture of
Future Information Systems. In IEEE Computer, 25(3),
pp. 38-48.
Wirfs-Brook, R., McKean, A., 2002. Object Design:
Roles, Responsibilities, and Collaborations. Addison-
Wesley.
A RESPONSIBILITY-DRIVEN ARCHITECTURE FOR MOBILE ENTERPRISE APPLICATIONS
129