# Binary Formats

Though JSON is a ubiquitous data format, it is not a very compact format suitable for data exchange, for instance over a network. Hence, the library supports

- [BSON](bson.md) (Binary JSON),
- [CBOR](cbor.md) (Concise Binary Object Representation),
- [MessagePack](messagepack.md), and
- [UBJSON](ubjson.md) (Universal Binary JSON)
- BON8

to efficiently encode JSON values to byte vectors and to decode such vectors.

## Comparison

### Completeness

| Format      | Serialization                                 | Deserialization                              |
|-------------|-----------------------------------------------|----------------------------------------------|
| BSON        | incomplete: top-level value must be an object | incomplete, but all JSON types are supported |
| CBOR        | complete                                      | incomplete, but all JSON types are supported |
| MessagePack | complete                                      | complete                                     |
| UBJSON      | complete                                      | complete                                     |
| BON8        | complete                                      | not yet implemented                          |

### Binary values

| Format      | Binary values | Binary subtypes |
|-------------|---------------|-----------------|
| BSON        | supported     | supported       |
| CBOR        | supported     | supported       |
| MessagePack | supported     | supported       |
| UBJSON      | not supported | not supported   |
| BON8        | not supported | not supported   |

See [binary values](../binary_values.md) for more information.

### Sizes

| Format             | [canada.json](https://github.com/nlohmann/json_test_data/blob/master/nativejson-benchmark/canada.json) | [twitter.json](https://github.com/nlohmann/json_test_data/blob/master/nativejson-benchmark/twitter.json) | [citm_catalog.json](https://github.com/nlohmann/json_test_data/blob/master/nativejson-benchmark/citm_catalog.json) | [jeopardy.json](https://github.com/nlohmann/json_test_data/blob/master/jeopardy/jeopardy.json) | [sample.json](https://github.com/nlohmann/json_test_data/blob/master/json_testsuite/sample.json) |
|--------------------|-------------|--------------|-------------------|---------------| ------------- |
| BSON               | 85,8 %      | 95,2 %       | 95,8 %            | 106,7 % (1)      | N/A (2)      |
| CBOR               | 50,5 %      | 86,3 %       | 68,4 %            | 88,0 %        | 87,2 %        |
| MessagePack        | 50,6 %      | 86,0 %       | 68,5 %            | 87,9 %        | 87,2 %        |
| UBJSON             | 53,2 %      | 91,3 %       | 78,2 %            | 96,6 %        | 88,2 %        |
| UBJSON (size)      | 58,6 %      | 92,3 %       | 86,8 %            | 97,4 %        | 89,3 %        |
| UBJSON (size+type) | 55,9 %      | 92,3 %       | 85,0 %            | 95,0 %        | 89,5 %        |
| BON8               | 50,5 %      | 83,8 %       | 63,5 %            | 87,5 %        | 85,6 %        |

Sizes compared to minified JSON value.

Notes:

- (1) The JSON value is an array that needed to be wrapped in an object to be processed by BSON. We used an empty object key for minimal overhead.
- (2) The JSON value contained a string with code point `U+0000` which cannot be represented by BSON.

The JSON files are part of the [nlohmann/json_test_data](https://github.com/nlohmann/json_test_data) repository.