J2ME - Java 2 Micro Edition (J2ME)/ Java, Micro Edition
(JME)
J2ME configurations
The configuration Layer is define the basic
defines the basic run-time environment as a set of core classes and a specific
JVM that run on specific kind of device based on memory constraints and
processor power. These are of two type - Connection Device Configuration
(CDC) use for large memory device, memory more than 2 MB and Connection
Limited Device Configuration (CLDC) use for small memory device, memory
small than 512 KB.
- Connected Device Configuration (CDC)
CDC is a
framework for Java ME defines the basic set of APIs, library, and
virtual-machine features for resource-constrained devices like pager, mobile
phones, and mainstream Personal Digital Assistants (PDAs) and must be
implemented into applications. It provide a standard platform for developers
for developing some complex application for embedded systems( from pager to
set-top boxes) by combined with one or more than one Profiles. CDC was
developed under the Java Community Process. It specifies a full Java
virtual Machine (JVM) called CVM (C Virtual Machine) and is used for 32- bit
architectures requiring more than 2 MB of memory.
CDC Memory - CDC target devices run a 32-bit microprocessor and
have more than 2 MB of memory, which is needed to store the C virtual
machine and libraries.
Specification of CDC launch under the Java
Community Process -
- CDC 1.0.2 (Java
Specification Request (JSR) 36 ).
- CDC 1.1.2 (Java
Specification Request (JSR) 218 ).
CDC requirements -
- Full Java language support
include exception handling and floating pointer support.
- Full Internationalization
support.
- Full Java Virtual Machine
(JVM) support in form of C Virtual Machine (CVM) with large amount of
memory about 2 MB.
Core application programming interfaces
(APIs) of CDC -
CDC support number of optional packages like Java
Remote Method Invocation (RMI) and Java DataBase Connectivity (JDBC), that
allow developers to access extra functionality within the restricted
resource constraints of a Java ME device.
- java.rmi
- java.sql and
javax.sql
- Connected Limited Device Configuration (CLDC)
CLDC is a framework for ME
defines the the basic set of APIs, library, and virtual-machine features for
resource-constrained devices like pager, mobile phones, and mainstream
Personal Digital Assistants (PDAs) and must be implemented into
applications. It provide a standard platform for developers for developing
some complex applications on embedded devices with limited resource such as
phones and pager by combined with one or more than one Profiles. CLDC was
developed under the Java Community Process. CLDC is build on “scale down”
version of Java virtual Machine (JVM) called KVM (Kilobytes Virtual Machine)
for 16 - bit or 32- bit device with limited amounts of memory like 512 KB.
CLDC memory - CLDC target devices with
slow network connections, limited power (often battery operated), 128 KB or
more of non-volatile memory, and 32 KB or more of volatile memory. Volatile
memory is non-persistent and has no write protection, meaning if the device
is turned off, the contents of volatile memory are lost. With non-volatile
memory, contents are persistent and write protected. CLDC devices use
non-volatile memory to store the run-time libraries and KVM, or another
virtual machine created for a particular device. Volatile memory is used for
allocating run-time memory.
Specification of CLDC launch under the Java Community Process
- CLCD 1.0 (Java
Specification Request (JSR) 30).
- CLCD 1.1 (Java
Specification Request (JSR) 139).
CLDC requirements -
- Full Java language support
except error handling, floating pointer support, and finalization.
- Limited
internationalization support.
- Full Java Virtual
Machine (JVM) support in form of Kilobytes Virtual Machine (KVM) with
limited amount of memory.
- Inherited classes - all
classes not specific to CLDC must be subsets of J2SE 1.3 classes.
- Classes specific to CLDC
are in javax.microedition
package and subpackages.
Core application programming interfaces
(APIs) of CLDC -
- java.io
- java.lang
- java.util
- contain Calendar and
Date classes.
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