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| Java ME |
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Getting Hands On to Java ME
Writing a Java ME application is different fromwriting the classical java application. Though it
uses the same basics programming constructs
as used with Java SE applications. Java ME
platform provides a better space to develop
games and applications for small devices like
PDA’s and handheld devices.
Basically there are two types of configurations
involved in Java ME application development
which are:
- CLDC (Connected Limited Device Configuration)
- CDC (Connected Device Configuration)
Architecture
Java ME architecture consists of layers highly
compatible with the native environment (i.e. OS)
of the device. These layers are collectively known
as the Connected Limited Device Configurations
(CLDC). The CLDC installed on the OS forms a
tine environment for small computing device.
The Java ME Architecture comprises of three
software layers:
- The first layer is the configuration layer
that includes the JVM, which directly
interacts with the native OS. The
Configuration layer also handles the
interaction between the profile and the
JVM.
- The second layer is the profile layer which
consists of the minimum set of application
programming interface (API) for the small
devices.
- The third layer is the Mobile Information
Device profile (MIDP) layer. The MIDP layer
contains java APIs for user network
connections, persistence storage, and the
user interface. It also has access to CLDC
libraries and MIDP libraries.
Connected Limited Device
Configuration (CLDC): This Configuration is
much popular among the developers community
to build the Java ME applications. CLDC defines |
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the core set of API and a virtual machine for
resource-constrained devices like mobile
phones, pagers, and mainstream personal digital
assistants.. There are two versions of CLDC:
First one is CLDC1.0 which was released in 2000
and very soon it was termed as Java
Specification Request (JSR) 30. Second one is
CLDC1.1 or more specifically as JSR 139
However 1.0 is much popular in use. When CLDC
is coupled with a profile such as the Mobile
Information Device Profile (MIDP), it provides a
solid Java platform for developing applications
to run on devices with limited memory,
processing power, and graphical capabilities.
Connected Device Configuration (CDC): Developed under the Java Community Process
(JCP), it is a standard framework of Java
technology used for building and delivering
application that can be shared over a wide range
of networks and devices ranging from pagers,
mobile phones, set top boxes and other PDA
devices. It comes in two flavors: First one is
JSR 36 (CDC 1.0) and second one is JSR 218
(CDC 1.1).
Mobile Information Device Profile (MIDP): The MIDP specification was defined through the
Java Community Process (JCP) by an expert
group of more than 50 companies, including
leading device manufacturers, wireless carriers,
and vendors of mobile software. MIDP provides
a standard Java runtime environment for various
mobile devices. It defines a platform for
dynamically and securely deploying optimized,
graphical, networked applications.
MIDP, when combined with the CLDC, provides
the Java runtime environment for the compact
mobile information devices, such as cell phones
and mainstream PDAs. Developers can develop
application once and then redistribute them into
various mobile information devices in a very small
period of time with help of MIDP. Its principal
functions include to provide the user interface,
network connectivity data storage and overall
application process management. The Mobile
Information Device Profile (MIDP) is a key element
of the Java Platform, ME.
There are two versions of MIDP: First one
MIDP 2.0 or JSR 118 and second one MIDP 1.0 or JSR 37. |
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Oct 2007 | Java Jazz Up | 16 |
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