Java Reference
In-Depth Information
CHAPTER 18
Seeking a Common
Platform
T
he balkanization of the Java ME platform is undoubtedly its weakest point. As you've
seen in the chapters throughout this part, a number of optional APIs enable you to
create compelling applications for the platform. Unfortunately, it's often difficult to
determine which devices support which of these APIs, and if you use more than a few
optional APIs in your application, you'll need to manage the combinatorial explosion
that results from the number of different optional APIs that may or may not be on tar-
get devices in the market. This fragmentation is an undesirable side effect of the JCP;
as vendors attempt to extend Java ME to support their device's features, they propose
new extensions to the Java ME platform. The JCP works reasonably well in ensuring
that when different vendors differentiate products, the new features are available via a
common API. However, it suffers from the presence of too many optional APIs from
which to choose. Many organizations active in the JCP recognize this problem and have
proposed several JSRs to address this problem.
In this chapter, I discuss the Java ME fragmentation problem in more detail, helping
you understand both why it occurs and what you can do to plan around it in your devel-
opment efforts. I talk more about the actual contents of the typical JSR, because for you
to become truly fluent as a Java ME developer, you need to be able to understand what a
JSR does and does not provide. I then examine in detail the three key JSRs that address
Java ME fragmentation today: JSR 185, which defines the Java Technology for the Wireless
Industry ( JTWI); JSR 248, which defines the Mobile Service Architecture (MSA) 1.0; and
JSR 249, which defines MSA2.
Understanding the Role JSRs Play
in Fragmentation
As you saw in Chapter 1, Java ME's roots as a platform for small computing devices drove
its creators to take a minimalist, lowest-common-denominator approach in which the
basic platform would contain little functionality. By adding new modules to the platform,
523
