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| 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. |
| |
| <h3>Type Codes</h3> |
| |
| Each typed bytes sequence starts with an unsigned byte that contains the type code. Possible values are: |
| <p> |
| <table border="1" cellpadding="2"> |
| <tr><th>Code</th><th>Type</th></tr> |
| <tr><td><i>0</i></td><td>A sequence of bytes.</td></tr> |
| <tr><td><i>1</i></td><td>A byte.</td></tr> |
| <tr><td><i>2</i></td><td>A boolean.</td></tr> |
| <tr><td><i>3</i></td><td>An integer.</td></tr> |
| <tr><td><i>4</i></td><td>A long.</td></tr> |
| <tr><td><i>5</i></td><td>A float.</td></tr> |
| <tr><td><i>6</i></td><td>A double.</td></tr> |
| <tr><td><i>7</i></td><td>A string.</td></tr> |
| <tr><td><i>8</i></td><td>A vector.</td></tr> |
| <tr><td><i>9</i></td><td>A list.</td></tr> |
| <tr><td><i>10</i></td><td>A map.</td></tr> |
| </table> |
| </p> |
| The type codes <i>50</i> to <i>200</i> are treated as aliases for <i>0</i>, and can thus be used for |
| application-specific serialization. |
| |
| <h3>Subsequent Bytes</h3> |
| |
| These are the subsequent bytes for the different type codes (everything is big-endian and unpadded): |
| <p> |
| <table border="1" cellpadding="2"> |
| <tr><th>Code</th><th>Subsequent Bytes</th></tr> |
| <tr><td><i>0</i></td><td><32-bit signed integer> <as many bytes as indicated by the integer></td></tr> |
| <tr><td><i>1</i></td><td><signed byte></td></tr> |
| <tr><td><i>2</i></td><td><signed byte (<i>0 = <i>false</i> and <i>1</i> = <i>true</i>)></td></tr> |
| <tr><td><i>3</i></td><td><32-bit signed integer></td></tr> |
| <tr><td><i>4</i></td><td><64-bit signed integer></td></tr> |
| <tr><td><i>5</i></td><td><32-bit IEEE floating point number></td></tr> |
| <tr><td><i>6</i></td><td><64-bit IEEE floating point number></td></tr> |
| <tr><td><i>7</i></td><td><32-bit signed integer> <as many UTF-8 bytes as indicated by the integer></td></tr> |
| <tr><td><i>8</i></td><td><32-bit signed integer> <as many typed bytes sequences as indicated by the integer></td></tr> |
| <tr><td><i>9</i></td><td><variable number of typed bytes sequences> <<i>255</i> written as an unsigned byte></td></tr> |
| <tr><td><i>10</i></td><td><32-bit signed integer> <as many (key-value) pairs of typed bytes sequences as indicated by the integer></td></tr> |
| </table> |
| </p> |
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