1. The Java Platform Micro Edition Java ME
Dr. Miguel A. Labrador
Department of Computer Science & Engineering

2. Outline The Java platform The Java ME platform
The Connected Limited Device Configuration (CLDC) 1.1
The Mobile Information Device Profile (MIDP) 2.0
Optional packages

3. Operating System Java Virtual Machine
The Java Platform
Operating System
Java Virtual Machine
Java Enterprise Edition
(Java EE)
Java Standard Edition
(Java SE)
Java Micro Edition
(Java ME)
TV set up boxes, cellular phones, smart phones, PDAs
PCs, laptops
Servers

4. The Java Platform
Source: Sun Microsystems white paper “Java 2 ME Building Blocks for Mobile Devices”

5. The Java Platform Micro Edition (Java ME)
Java platform for mobile devices and embedded systems
Resource-constrained in terms of CPU, memory, energy
Smallest footprint and smallest VM
Differentiates between different types of resource-constrained devices
Some with more resources, such as set up boxes, automobile navigation systems
More constrained devices, such as cellular phones, PDAs, pagers
Architecture has four layers
JVM that sits on top of the operating system
The configuration layer
The profile layer
Optional packages layer

6. Operating System Java Virtual Machine
The Java ME Platform
Operating System
Java Virtual Machine
Optional Packages
Connected Limited Device Configuration
(CLDC)
Connected Device Configuration
(CDC)
Mobile Information Device Profile
(MIDP)
Foundation Profile
Personal Profile

7. More resource-constrained devices
The Java ME Platform
More resource-constrained devices
Operating System
Java Virtual Machine
Optional Packages
Connected Limited Device Configuration
(CLDC)
Connected Device Configuration
(CDC)
Mobile Information Device Profile
(MIDP)
Foundation Profile
Personal Profile

8. The CLDC 1.1
Targets devices with 192KB of memory, 16-bit or 32-bit processors, low power consumption, intermittent connectivity and limited bandwidth
Cell phones, pagers, PDAs, and the like
Contains core Java libraries (java.lang.*; java.utili.*) and APIs for input/output, security, and networking
Java programming language and VM features
Libraries and APIs

9. Java Programming Language and VM features
Floating point support
Float and Double
Calendar, Date, Timezone, and Thread objects redesigned to be more Java SE-compliant
JVM the same as the one used in Java SE, except:
No finalization of class instances
Method Object.finalize() not included
Exemption and error handling limitations
User-defined class loaders are not supported
Thread groups not supported; only individual threads
Class file verification not supported
Only offline preverification with stack maps

10. The Preverification Process
Source: Sun Microsystems white paper “Java 2 ME Building Blocks for Mobile Devices”

11. Libraries and APIs
For upward compatibility, CLDC 1.1 includes libraries that are a subset of the standard libraries included in Java SE and EE platforms
System classes essential to the Java programming language
Java.lang package: java.lang.Object, *.Class, *.Runtime, *.System, *.Thread, *.Runnable, *.String, *.StringBuffer, *.Throwable
Data type classes
Java.lang.Boolean, *.Byte, *.Short, *.Integer, *.Long, *.Float, *.Double, *.Character
Collection classes
Java.util.Vector, *.Stack, *.Hastable, *.Enumeration, *.Random, *.Math
Input/Output classes
Java.io.InputStream, *.OutputStream, *.ByteArrayInputStream, *.ByteArrayOutputStream, *.DataInput, *.DataOutput, *.DataInputStream, *.DataOutputStream, *.Reader, *.Writer, etc.

12. Libraries and APIs CLDC also includes some specific classes
Calendar and Time classes
Java.util.Calendar, *.Date, *.TimeZone
Exception and Error classes
Java.util.Exception, *.AruthmeticException, *.ArrayStoreException, *.NullPointerException, *.NumberFormatException, *.RuntimeException, *.SecurityException, others.
Java.lang.Error, *.NoClassDefFoundError, *.OutOfMemoryError, *.VirtualMachineError
CLDC also includes some specific classes
Described within the Generic Connection Framework (GCF)
Provide minimum input/output and networking support needed by all devices while opening the door for extending these capabilities and implementing new ones as needed by specific devices
Reduces footprint

13. Libraries and APIs
GCF included in the javax.microedition.io package and implements six basic Connection APIs
InputConnection
openInputStream and openDataInputStream methods
OutputConnection
openOutputStream and openDataOutputStream methods
StreamConnection
Combines InputConnection and OutputConnection interfaces
Two way communication
ContentConnection
Sub-interface of the StreamConnection interface that provides basic information contained in HTTP connections
StreamConnectionNotifier
acceptAndOpen method to block client program and wait for connection

14. Libraries and APIs
DatagramConnection
Implements several methods to handle input/output of datagrams
Receive(), send(), getMaximunLength()
The GCF includes a general abstraction to handle all forms of communications
Connector.open (“<protocol>:<address>;<parameters>”);
Connector.open(
Connector.open(“socket:// :2800”);
Connector.open(“comm:0;baudrate=4800”);
Connector.open(“datagram:// :2800”);

15. The MIDP 2.0
If the CLDC is a contract between the device and the Java programming language, the MIDP is a contract between the Java programming language and the application developer
MIDP is the profile defined for CLDC devices
Minimum set of APIs required to develop graphical and networked applications for resource-constrained mobile devices or MIDlets
User Interface APIs, Game APIs, Networking APIs, Security APIs, Sound APIs, Storage APIs
MIDlets and MIDlets development will be covered right after this topic

16. Optional Packages
The Java ME platform is very rich in additional packages
Mobile Media API (JSR 135)
Access and control multimedia resources and files. The Sound API included in MIDP is a subset of this API
Security and Trust Services API (JSR 177)
Session Initiation Protocol API (JSR 180)
Mobile 3D Graphics API (JSR 184)
Event Tracking API (JSR 190)
Wireless Messaging API (JSR 120)
Location API (JSR 293)
Java ME Web Services API (JSR 172)
Many others