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Smile

Smile is a binary encoding of the JSON data model, designed by the Jackson project. A Smile document usually starts with a four-byte header: the ASCII smiley :) , a newline, and a flags byte (3A 29 0A plus flags). The living spec is smile-specification.md (BSD-2-Clause).

There is no official OSI-licensed test corpus. Cases are original (names n, kelp, harbor). Token byte values are facts from the spec, not a copied example file.

Versions

Version Parser-visible difference
1.0 Header, literals (null / true / false / empty string), small integers, short ASCII strings, arrays (0xF8…0xF9) and objects (0xFA…0xFB).
1.0 shared names Flags bit 0 is set. After the decoder has seen a field name, a later object may repeat that name with a one-byte back-reference instead of writing the letters again.
1.0.4 Clarifications in the 2013 spec: 32-bit int token 0x24, 32-bit float 0x28, optional end marker 0xFF, reserved 0xFE, and a version nibble that must be 0.

A back-reference is a short token that means “the same string as slot k in the table I have been building.” A nibble is four bits. The high nibble of the flags byte is the format version; only version 0 is defined.

What the cases cover

  • Literals, small integer 7, string kelp, empty array and object
  • Object {n: 7} and {harbor: kelp}
  • Shared-name header and a two-object array that reuses key n
  • 32-bit integer 31, float 1.5, null followed by 0xFF
  • Rejects: missing or truncated header, bad magic, unclosed array, reserved 0xFE, unused token 0x00, version nibble 1

Catalog: compliance/data/smile/. Inputs are hex.

Python serializer

newsmile.SmileDecoder. The older PyPI package pysmile 0.2 is Python 2 and is not a dependency.

Typical catalog pattern (report-only):

  • pass the 1.0 literals and containers
  • fail the shared-name back-reference if the decoder never stored the first key
  • fail the “version nibble must be 0” reject if the decoder ignores the nibble and still reads the value