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.

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!