New I/O (JSR 51)

1
New I/O (JSR 51)

• Robert Rock Howard
• Chief Technology Officer
• Tower Technology

2
New Features

• Scalable Network I/O
• High Performance File I/O
• Pluggable Characters Sets
• Character conversion
• Regular Expressions
• Features considered but not included
• Formatting and scanning
• Improved filesystem interface

3
New Abstractions

• Channels
• Connections for I/O
• Buffers
• Containers for primitive data
• Charsets (decoders, encoders)
• Pattern Matchers
• Selectors
• Selectable channels

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Channels

• Defined by interface classes
• Reading, writing
• Inherit both for bi-directional I/O
• Asynchronous Closing and Interruption
• Defined methods are a grab bag of utilities for
  buffer manipulation.

5
Buffers

• Based on primitive types
• For int, long, float, double, char, etc.
• On Heap or else managed directly (not GCd)
• Memory mapped files are allowed
• Indexes are managed wrt. of primitives
• Big or little endian hidden in implementation
• Nice set of operators for manipulating buffers
  (reading, writing, managing indices, etc.)

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Random Notes New I/O

• Buffer operations return the buffer so that they
  can be chained
• MyIntbuffer.clear().write(17)
• Selector allows monitoring of many channels via a
  single thread
• Old I/O unchanged and retained in entirety

7
Random Notes JDK 1.4

• The thread stack size can be set via a new Thread
  constructor
• JVMPI and JVMDI (profiling and debugging
  interfaces) are being replaced
• See JSRs for debugging, profiling, monitoring
• New Assert capability can be enabled
• Usage assert expression
• Optional Usage assert expression error_message
  
• Generates AssertionError if triggered
• Make sure there are no side effects in assert
  expression!

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Conclusion

• The new I/O mechanism is sufficiently powerful
  and scalable that I expect all major commercial
  Java frameworks to be rewritten for them within 6
  to 12 months.
• The APIs are simple enough that you can pick them
  up in about one day of concentrated effort.

Go For It!