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The Java Platform Micro Edition Java ME

The Java Platform Micro Edition Java ME. Dr. Miguel A. Labrador Department of Computer Science & Engineering labrador@csee.usf.edu http://www.csee.usf.edu/~labrador. Outline. The Java platform The Java ME platform The Connected Limited Device Configuration (CLDC) 1.1

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The Java Platform Micro Edition Java ME

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  1. The Java Platform Micro EditionJava ME Dr. Miguel A. Labrador Department of Computer Science & Engineering labrador@csee.usf.edu http://www.csee.usf.edu/~labrador

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

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

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

  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 • 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(http://www.csee.usf.edu); • Connector.open(“socket://192.168.0.2:2800”); • Connector.open(“comm:0;baudrate=4800”); • Connector.open(“datagram://192.168.0.2:2800”);

  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

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