02 cldc
- 1. CLDC Connected, Limited Device Configuration Cornelius Koo - 2005
- 2. CLDC Devices Characteristics • 160 - 512 kb total memory available for java platform • 16 bit / 32 bit processor • low power consumption, often battery powered • intermitten network connectivity (often wireless), limited bandwith
- 3. Hardware Requirements • CLDC doesnt have specific hardware requirements • Minimal memory requirements : • 128 kb - for running the JVM and CLDC libraries. This memory must preserve its content, even when the device is powered off. (Nonvolatile memory) • 32 kb - available during application runtime for allocation of objects. (Volatile memory / heap)
- 4. Software Requirements • The Operating System must be able to running JVM and managing Java applications on the device including : Select and launch application Remove application
- 5. JVM Specification for CLDC
- 6. Java Language for CLDC • CLDC doesn’t support floating point type. (double and float) • CLDC doesn’t support finalize() method. • CLDC only support limited set of Exception classes for error handling.
- 7. Java Virtual Machine for CLDC • JVM doesn’t support floating point operation. • JVM doesn’t support native interface and native method invocation. • Reflection is not available. • JVM must implement the classloader. • finalize() method is not available. • JVM doesn’t suport ThreadGroup class. • JVM doesn’t support weak references.
- 8. Weak References • Garbage collector recognizes that an object is being referenced, yet the object is still a candidate for garbage collection.
- 9. Security Handling • Any devices running Java application will need protection from malicious codes that may access system information or resources. • This “Low Level” protection is implemented through class file verification.
- 10. CLDC Class File Verification • Class file verification is done in 2 steps in CLDC. • 1st Step is pre-verification. • 2nd Step is in-device verification.
- 11. Pre-Verification • Pre-verification : • A software program is run to insert additional attributes into the class file. • Class file will be approximately 5% larger after pre-verification. • Done as part of development process or before a class file is loaded on a device. • A "Stack Maps" is added to the class file, describing what variables and operands are art of the interpreter stack space.
- 12. In-Device Verification • In-Device verification : • Once a device loads a pre-verified class file, the in-device verifier runs through each instruction. • There are several checks done to validate the code. • At any point the verifier can report and reject the class file. • Code verifier program for KVM is in the range of 10kb and less than 100 bytes of heap space required.
- 13. CLDC Package
- 14. Java Classes
- 15. System Classes • java.lang.Class • java.lang.Object • java.lang.Runnable • java.lang.Runtime • java.lang.String • java.lang.StringBuffer • java.lang.System • java.lang.Thread • java.lang.Throwable
- 16. Data Type Classes • java.lang.Boolean • java.lang.Byte • java.lang.Character • java.lang.Integer • java.lang.Long • java.lang.Short
- 17. Collection Classes • java.util.Enumeration • java.util.Hashtable • java.util.Stack • java.util.Vector
- 18. I/O Classes • java.io.ByteArrayInputStream • java.io.ByteArrayOutputStream • java.io.DataInput • java.io.DataInputStream • java.io.DataOutput • java.io.DataOutputStream • java.io.InputStream • java.io.InputStreamReader • java.io.OutputStream • java.io.OutputStreamWriter • java.io.PrintStream • java.io.Reader • java.io.Writer
- 19. Calendar and Time Classes • java,util.Calendar • java.util.Date • java.util.TimeZone
- 20. Utility Classes • java.util.Math • java.util.Random
- 21. Exception Classes • java.io.EOFException • java.io.InterruptedIOException • java.io.IOException • java.io.UnsupportedEncodingException • java.io.UTFDataFormatException • java.lang.ArithmeticException • java.lang.ArrayIndexOutOfBoundsException • java.lang.ArrayStoreException • java.lang.ClassCastException • java.lang.ClassNotFoundException • java.lang.Exception • java.lang.IllegalAccessException • java.lang.IllegalArgumentException
- 22. Exception Classes • java.lang.IllegalMonitorStateException • java.lang.IllegalThreadStateException • java.lang.IndexOutOfBoundsException • java.lang.InstantiationException • java.lang.InterruptedException • java.lang.NegativeArraySizeException • java.lang.NullPointerException • java.lang.NumberFormatException • java.lang.RuntimeException • java.lang.SecurityException • java.lang.StringIndexOutOfBoundsException • java.util.EmptyStackException • java.util.NoSuchElementException
- 23. Error Classes • java.lang.Error • java.lang.OutOfMemoryError • java.lang.VirtualMachineError
- 24. Internationalization • java.io.InputStreamReader • java.io.OutputStreamWriter • both can be used to convert from bytes to/from unicode.
- 25. Reference • Core J2ME Technology and MIDP. John W. Muchow. Prentice Hall PTR, 2002. • Enterprise J2ME: Developing Mobile Java Applications. Michael Juntao Yuan. Prentice Hall PTR, 2003. • J2ME in A Nutshell. Kim Topley. Oreilly, 2002. • Wireless J2ME Platform Programming. Vartan Piroumian. Prentice Hall, 2002.