org.apache.hadoop.typedbytes (Hadoop 0.20.1+169.88 API)
Date: 2010-05-20

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## Package org.apache.hadoop.typedbytes

Typed bytes are sequences of bytes in which the first byte is a type code.

See:
Description

Class Summary
TypedBytesInput | Provides functionality for reading typed bytes.
TypedBytesOutput | Provides functionality for writing typed bytes.
TypedBytesRecordInput | Serializer for records that writes typed bytes.
TypedBytesRecordOutput | Deserialized for records that reads typed bytes.
TypedBytesWritable | Writable for typed bytes.
TypedBytesWritableInput | Provides functionality for reading typed bytes as Writable objects.
TypedBytesWritableOutput | Provides functionality for writing Writable objects as typed bytes.

Enum Summary
Type | The possible type codes.

## Package org.apache.hadoop.typedbytes Description

Typed bytes are sequences of bytes in which the first byte is a type code. They are especially useful as a (simple and very straightforward) binary format for transferring data to and from Hadoop Streaming programs.

### Type Codes

Each typed bytes sequence starts with an unsigned byte that contains the type code. Possible values are:

Code | Type
--- | ---
0 | A sequence of bytes.
1 | A byte.
2 | A boolean.
3 | An integer.
4 | A long.
5 | A float.
6 | A double.
7 | A string.
8 | A vector.
9 | A list.
10 | A map.

The type codes 50 to 200 are treated as aliases for 0, and can thus be used for application-specific serialization.

### Subsequent Bytes

These are the subsequent bytes for the different type codes (everything is big-endian and unpadded):

Code | Subsequent Bytes
--- | ---
0 | <32-bit signed integer> <as many bytes as indicated by the integer>
1 | <signed byte>
2 | <signed byte (0 = false and 1 = true)>
3 | <32-bit signed integer>
4 | <64-bit signed integer>
5 | <32-bit IEEE floating point number>
6 | <64-bit IEEE floating point number>
7 | <32-bit signed integer> <as many UTF-8 bytes as indicated by the integer>
8 | <32-bit signed integer> <as many typed bytes sequences as indicated by the integer>
9 | <variable number of typed bytes sequences> <255 written as an unsigned byte>
10 | <32-bit signed integer> <as many (key-value) pairs of typed bytes sequences as indicated by the integer>

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