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state and not even visible to the entire community. However, it's worth discussing both,
because it's not clear which the market will eventually adopt, and both provide an excel-
lent framework for discussing the immediate future of the Java ME platform.
Like the JTWI before it, the MSA defines a collection of APIs that conformant devices
must support, and it provides specific clarifications regarding ambiguities surrounding
many of those APIs. Together, MSA 1.0 and MSA2 define five different permutations of
optional Java ME APIs for mass-market phones using technologies and APIs readily avail-
able either now or in the near future.
Understanding MSA 1.0
The efforts to craft MSA 1.0 began some two years after the completion of the JTWI, and
you can see this clearly when you look at the number and types of optional interfaces it
requires for conformance. The JSR defining MSA 1.0 specifies mandatory components
and requirements that must be fulfilled, as well as
conditionally mandatory
requirements
that must be fulfilled if specific conditions set out in the JSR are met.
The JSR contains five key sections that describe the mandatory component JSRs,
additional clarifications about component JSRs, additional platform requirements
above and beyond the JSRs, various recommendations for developers, and a roadmap
detailing a tentative future for Java ME and the MSA. The expert group behind the
specification consists of major players in the Java ME market, including hardware
manufacturers such as Motorola, Nokia, Research In Motion, Samsung, Siemens,
and Sony, as well as network operators including Cingular Wireless (now part of AT&T
Mobility), NTT docomo, Orange, Sprint, T-Mobile, and Vodafone, as well as of course
Sun. The specification defines two platforms:
MSA
and
MSA Subset
. (To avoid confu-
sion with MSA2 that JSR 249 defines, I'll refer to these as MSA 1.0 and MSA Subset 1.0.)
As the name suggests, MSA 1.0 is a full software stack, while MSA Subset 1.0 eliminates
several optional software packages for lower-cost, less-powerful devices. In order to
meet the requirements of either of these platforms, a compliant implementation must
implement or comply with
•
JSRs
: It must implement every JSR indicated as a required component for the plat-
form as specified by MSA 1.0 or MSA Subset 1.0
•
Additional clarifications for JSRs
: It must comply with any additional MSA 1.0 or
MSA Subset 1.0 requirements as detailed in the JSR's relevant “Additional Clarifica-
tions” section
•
Additional requirements:
It must comply with all of the additional MSA require-
ments set out in JSR 248
