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any other third-party application. The only difference is that it is a very
big application. The phrase 'the tip of the iceberg' describes quite well
the Java ME subsystem as seen from the point of view of the user of Java
applications. Only a small part of something largely hidden can be seen
(see Figure 10.1). Underneath every lightweight Java application, there is
a very big and highly complex engine. There is a very good reason for
that. The Java ME platform is a huge abstraction layer (composed of many
internal abstraction layers) that lets you deploy and run a 'Hello, World'
application in less than 10 lines of Java code on a variety of completely
different platforms!
Figure 10.1 An iceberg
The Java ME specifications define a few core logical entities (see
Figure 10.2), such as the application management system (AMS), the
profile (MIDP) and the configuration (VM and base classes). However,
the separation between entities is mostly logical, which leaves room for
different possible implementations.
Java ME platform
Native platform
Figure 10.2 Core logical entities of Java ME
Although we discuss only the implementation on Symbian OS, there
are other implementation models. For example, the open-source PhoneME
project 2
takes a highly generic and modular approach that is designed
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