Java Reference
In-Depth Information
Symbian OS is an open platform which allows installation of after-
market applications. Symbian OS devices can be customized by licensees
to be shipped with a large number of pre-integrated applications which
must interoperate and provide a consistent user experience. Symbian OS
is a multitasking operating system that can run more than one application
at the same time.
If the Java ME subsystem were not integrated with the native services,
the user experience of after-market applications would be different from
one application to another and also from pre-integrated applications.
Specifically, we would have noticed the following fragmentation:
From a user-interface (UI) perspective: Java applications would look
different to the native UI platform (e.g., different background and fore-
ground colors, different skins, and different locations of soft buttons)
From a multimedia perspective: Playing and recording of multimedia
formats and content would not have uniform support for Java and
native applications
From a phone-usage perspective: Java applications would not enjoy
the rich usability features of native applications (e.g., task manager,
touch-screen support, support for multiple languages)
From a multitasking perspective: Java applications might have prob-
lems competing for system resources while running at the same time
as native applications
From a developer perspective: some of the application-level protocols
would behave differently in Java applications compared to native
applications (and that could possibly impact
the features of
applications using the specific application-level protocol).
More examples could be given and, in many low-end mobile platforms,
it is indeed the case that, due to the lack of native services, the Java ME
platform comes with an internal implementation for some JSRs (in low-end
devices, Java is sometimes the only downloadable applications execution
environment and therefore there is no other alternative: you either use
Java ME or only pre-installed applications).
However, having an application execution environment showing dif-
ferent behavior to native applications is not acceptable in a high-end
mobile platform with high standards of interoperability, such as Symbian
OS. The strategic approach, from the early days of Java on Symbian OS
and to provide consistent application execution environments and user
experience, is to tightly integrate the Java ME APIs with native Symbian
OS services, which ensures that high standards of interoperability are
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