EXI for JSON - How EXI can be used to represent JSON data efficiently
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README.md

Overview

exificient-for-json is an implementation of the EXI4JSON specification (see https://www.w3.org/TR/exi-for-json/) in Java. EXI4JSON converts JSON to event streams which result in a very processing efficient and compact format. Lossless round-trip conversion back to the original JSON structures is supported. EXI4JSON is based on EXI and uses its built-in datatypes.

The project uses MIT license.

Build Status

Background

Due to its EXI/XML nature EXI4JSON can be serialized/visualized as XML. Most of the use-case do not need this features but in some situation it may turn out very hand.

A JSON example

{
  "keyNumber": 123,
  "keyArrayStrings": [
    "s1",
    "s2"
  ]
}

can be transformed to

<j:map xmlns:j="http://www.w3.org/2015/EXI/json">
  <j:keyNumber>
    <j:number>123</j:number>
  </j:keyNumber>
  <j:keyArrayStrings>
    <j:array>
      <j:string>s1</j:string>
      <j:string>s2</j:string>
    </j:array>
  </j:keyArrayStrings>
</j:map>

How to get it

Released with Maven

<dependency>
    <groupId>com.siemens.ct.exi</groupId>
    <artifactId>exificient-for-json</artifactId>
    <version>1.0.0</version>
</dependency>

or also as snapshot.

<dependency>
    <groupId>com.siemens.ct.exi</groupId>
    <artifactId>exificient-for-json</artifactId>
    <version>1.0.1-SNAPSHOT</version>
</dependency>

How to use the library

Java API for JSON Processing

// generate by simply providing input and output
EXIforJSONGenerator e4jGenerator = new EXIforJSONGenerator();
e4jGenerator.generate(isJSON, osEXI4JSON);
// Note: one can also fire events like writeStartObject(),  writeKeyName(key) etc

// parse by simply providing input and output again
EXIforJSONParser e4jParser = new EXIforJSONParser();
e4jParser.parse(isEXI4JSON, osJSON);
// Note: one can again read events by readNextEvent(), getKeyName(),  getValueString() etc

Jackson

EXI4JSONFactory fEXI = new EXI4JSONFactory();
ObjectMapper mapperEXI = new ObjectMapper(fEXI);
ObjectMapper mapperJSON = new ObjectMapper();

String carJson =
    "{ \"brand\" : \"Mercedes\", \"doors\" : 5 }";
JsonNode car = mapperJSON.readTree(carJson); 

// generate
OutputStream e4jOS = ...; // output stream
mapperEXI.writeTree(fEXI.createGenerator(e4jOS), car);
// parse
OutputStream e4jIS = ...; // input stream
EXI4JSONParser eparser = fEXI.createParser(e4jIS);
JsonNode carAgain = mapperJSON.readTree(eparser);

Compression Results

See test-data in https://github.com/EXIficient/exificient-for-json/tree/master/src/test/resources.

TestCase JSON [Size in Bytes] CBOR [Size in Bytes] Smile [Size in Bytes] EXI4JSON [Size in Bytes]
glossary.json 605 311 309 322
gpx\sample-set-1\gpx-1-100pts.json 11007 7378 6592 6210
gpx\sample-set-1\gpx-1-10pts.json 1318 898 832 778
gpx\sample-set-1\gpx-1-1pts.json 314 248 254 223
gpx\sample-set-1\gpx-1-200pts.json 21661 14578 12992 12179
gpx\sample-set-1\gpx-1-20pts.json 2424 1618 1472 1395
gpx\sample-set-1\gpx-1-2pts.json 426 322 320 284
gpx\sample-set-1\gpx-1-300pts.json 32452 21778 19392 18216
gpx\sample-set-1\gpx-1-30pts.json 3480 2338 2112 1984
gpx\sample-set-1\gpx-1-3pts.json 537 394 384 346
gpx\sample-set-1\gpx-1-400pts.json 43257 28978 25792 24239
gpx\sample-set-1\gpx-1-40pts.json 4562 3058 2752 2588
gpx\sample-set-1\gpx-1-4pts.json 648 466 448 408
gpx\sample-set-1\gpx-1-500pts.json 53988 36178 32192 30256
gpx\sample-set-1\gpx-1-50pts.json 5634 3778 3392 3191
gpx\sample-set-1\gpx-1-5pts.json 760 538 512 469
gpx\sample-set-1\gpx-1-600pts.json 64758 43378 38592 36284
gpx\sample-set-1\gpx-1-60pts.json 6720 4498 4032 3801
gpx\sample-set-1\gpx-1-6pts.json 872 610 576 531
gpx\sample-set-1\gpx-1-700pts.json 75518 50578 44992 42285
gpx\sample-set-1\gpx-1-70pts.json 7778 5218 4672 4396
gpx\sample-set-1\gpx-1-7pts.json 983 682 640 593
gpx\sample-set-1\gpx-1-800pts.json 86292 57778 51392 48293
gpx\sample-set-1\gpx-1-80pts.json 8859 5938 5312 5000
gpx\sample-set-1\gpx-1-870pts.json 93786 62818 55872 52476
gpx\sample-set-1\gpx-1-8pts.json 1094 754 704 655
gpx\sample-set-1\gpx-1-90pts.json 9942 6658 5952 5609
gpx\sample-set-1\gpx-1-9pts.json 1206 826 768 716
json-generator.com\2015-01-06\01.json 1103353 490133 351756 310012
json-generator.com\2015-01-06\02.json 2203693 979469 703115 606056
json-generator.com\2015-01-06\03.json 3238056 1438370 1032056 881484
json-generator.com\2015-01-06\04.json 4320187 1918771 1376620 1168143
json-generator.com\2015-01-06\05.json 5425885 2409849 1728913 1461451
json-generator.com\2015-01-06\06.json 6509681 2890828 2073670 1749445
json-generator.com\2015-01-06\07.json 7620054 3383755 2427181 2044025
json-generator.com\2015-01-06\08.json 8880856 3943588 2828669 2379084
json-generator.com\2015-01-06\09.json 9982416 4433013 3179808 2672229
json-generator.com\2015-01-06\10.json 11080993 4920626 3529384 2965358
openweathermap.org\sample-set-1\owm-1-1000cities.json 622540 514167 311697 223442
openweathermap.org\sample-set-1\owm-1-100cities.json 62024 51074 30877 23032
openweathermap.org\sample-set-1\owm-1-10cities.json 6170 5069 3205 2629
openweathermap.org\sample-set-1\owm-1-1cities.json 615 502 464 486
openweathermap.org\sample-set-1\owm-1-200cities.json 123811 101857 61272 44954
openweathermap.org\sample-set-1\owm-1-2cities.json 1231 1011 773 726
openweathermap.org\sample-set-1\owm-1-300cities.json 185699 152787 91855 67573
openweathermap.org\sample-set-1\owm-1-400cities.json 247718 203877 122640 90258
openweathermap.org\sample-set-1\owm-1-500cities.json 309532 254791 153303 112848
openweathermap.org\sample-set-1\owm-1-50cities.json 31048 25557 15534 11820
openweathermap.org\sample-set-1\owm-1-5cities.json 3136 2587 1728 1535
openweathermap.org\sample-set-1\owm-1-600cities.json 371839 306314 184489 133633
openweathermap.org\sample-set-1\owm-1-700cities.json 433746 357313 215231 156390
openweathermap.org\sample-set-1\owm-1-800cities.json 498084 411365 249407 179022
openweathermap.org\sample-set-1\owm-1-900cities.json 560315 462826 280620 201229

On average "EXI4JSON" is about 48% of the original JSON filesize! On average "EXI4JSON" is about 50% smaller than the CBOR binary encoded file!

Compression Figure