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J2MEFAQ_WhatIsJ2ME
The JVM for CLDC devices is called KVM with its name refering to the fact that the JVM is in kilobytes in size. This KVM is limited in that only a subset of the standard bytecode verifier is present. Native methods cannot be added at runtime.
The JVM for CDC devices is caleld the CVM with its name refering to being a network connected device.
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J2MEFAQ_WhatIsJ2ME
What is J2ME
J2ME is designed to fit a specific edition of java on mobile devices such as PDAs, handsets, set boxes, and embedded devices in transport vehicles. Sun first introduced J2ME during the JavaOne conference in 1999. Other explorations into Java on Mobile devices before J2ME were PersonalJava and JavaPhone.Configurations
J2ME is divided into configurations and profiles. Configurations simply specify a Java Virtual Machine(JVM) and a core set of APIs for a specific family of devices. There are two configurations in J2ME, CLDC and CDC.Connected Limited Device Configuration(CLDC)
The CLDC covers those devices in the famliy of connection limited deivces that are in the 160k to 512k memory range. Connected Limited refers to the fact that the network connection is intermittent.The JVM for CLDC devices is called KVM with its name refering to the fact that the JVM is in kilobytes in size. This KVM is limited in that only a subset of the standard bytecode verifier is present. Native methods cannot be added at runtime.
Connected Device Configuration(CDC)
The CDC covers those devices in the family of connected devices in the memory range fo 512k or higher. Connected Device refers to the fact that the network connection is not intermittent but steady, ie sockets.The JVM for CDC devices is caleld the CVM with its name refering to being a network connected device.
Profiles
Profiles add functionality to a famliy of devices that support through added classes and a packages in that Profile API. Profiles that are within the J2ME famliy at the moment are:- MIDP-CLDC based devices
- PDAP-CLDC based devices for low end PDAs
- Foundation-CDC based devices
- Personal-CDC based contains the APIS from PersonalJava
- RMI-CDC based devices
- Personal Basis-CDC based devices
- Multimedia-CLDC and CDC based devices
- Gaming-CDC and CLDC based devices
- Telephony(WTCA)-CDC and CLDC based devices
- Information Module Profile(IMP)-CLDC based devices with limited graphics such as alarms and etc
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