Information Technology Reference
In-Depth Information
Programming Models and Synchronization
Techniques for Disconnected Business
Applications
A V R A H A M L E F F A N D J A M E S T. R A Y F I E L D
IBM T.J. Watson Research Center
P.O. Box 704
Yorktown Heights, NY 10598
USA
Abstract
Programming models usefully structure the way that programmers approach
problems and develop applications. Business applications need properties such
as persistence, data sharing, transactions, and security, and various programming
models exist—for connected environments—that facilitate the development of
applications with these properties. Recently, it has become possible to con-
sider running business applications on disconnected devices. Developers thus
confront two areas of concern. The first is to solve the pragmatic problems of
how to implement the properties required by business applications in a discon-
nected environment. The second is to determine whether programming models
for disconnected environments exist (as they do for connected environments) that
facilitate the development of business applications.
This chapter discusses these two areas of concern. We explain why busi-
ness applications are particularly hard to “project” to disconnected devices. We
then introduce some of the approaches used to solve these problems (focusing
especially on
data replication
and
method replay
techniques), and the program-
ming models that exist for the disconnected environment. Finally, we analyze
whether connected programming models for business applications can be use-
fully projected to disconnected environments. We compare the data replication
and method replay approaches, discuss the features of each, and show that a
connected programming model is useful even in a disconnected environment.
