record stores allowed in the RMS, Unicode support and some threading
requirements. While this was a great start, more needed to be done. JTWI
served as a necessary consolidation point in the evolution of the mobile
industry, but there were still many JSRs in the world of Java ME.
The Mobile Services Architecture 16 (JSR-248, MSA), finalized in
December 2006, mandated that an MSA-compliant device is JTWI-
compliant and implements a much wider range of JSRs. The specification
defines two categories of MSA, known as Full MSA and MSA Subset (see
Figure 1.6 Mobile Services Architecture: a) Full MSA and b) MSA subset (adapted from
[Ortiz 2007, Figure 3])
MSA is a huge step forward and the number of MSA-compliant devices
available in the market is increasing all the time. Have a look at the Java
ME device registry at Sun, which lists some of them, to see how MSA has
raised the bar. (For more information on MSA, see Chapter 6.)
1.6 Why Use Java ME on Symbian OS?
Why not just use Symbian C++? That's a good question. To answer it, we
need to look firstly at what people do with their smartphones and then
how it is achieved technically.