Java Reference
In-Depth Information
There are countless packages for Java ME; many of the now-standard interfaces that
are part of successful MIDP-based devices are in fact packages. In this topic, you will
learn how to use several packages, including
• The GCF, documented in JSR 30
• The
FileConnect
interface, which provides local file access on MIDP and is
documented in JSR 75
• The Java Bluetooth API, documented in JSR 82
• The Wireless Messaging API, documented in JSR 120
• The Web Services API, documented in JSR 172
• The Java Advanced Graphics and User Interface (AGUI) API, for CDC devices,
documented in JSR 209
• The Java Mobile Service Architecture (MSA), documented in JSR 248
Planning Your Approach to Java ME Development
Java ME's strength is rooted in the ubiquity of Java today. However, with this ubiquity
comes challenges. The multitude of APIs and the diversity of distribution channels make
planning the technical and business aspects of your application equally important.
Selecting Appropriate Device Targets
As you've seen, the triad of configurations, profiles, and packages means managing a
lot
of different APIs. For many kinds of applications, this may not be a serious problem—
most productivity and network applications need just a network layer, some GUI
elements, and a persistent store, which is available under just about any combination
of configuration and profile you might encounter.
That's not always the case, however. Your application might depend on functional-
ity present in only a specific package, perhaps, either by design (say, a Bluetooth-
derived application for proximity detection) or product differentiation. There's always
the temptation of using an optional package to speed time to market, too, only to find
later that it's not available on the next target for your product.
Consequently, if portability is important, you should base your application on as
few Java ME packages as you possibly can. Obviously, this doesn't mean creating your
own control framework from scratch or implementing your own web services frame-
work from scratch if you don't have to. But it does mean understanding what APIs are
