2. JSR 353: Java API for JSON Processing
John Clingan
Java EE and GlassFish Product Manager

3. Agenda
JSON Overview
JAX-RS and JSON
JSR 353
JSON API

4. JSON Overview Lightweight Data Exchange Format
Easy for humans/machines to read and write
Minimal. Compact, textual, and subset of JavaScript
Example: {“name” : “John”, “age”:20, “phone”:[“ ”, “ ”]}
Used heavily in RESTful web services, configuration, databases, browserserver communication

5. JSON Overview Used by popular websites in their RESTful Web Services
Facebook, Twitter, Amazon
Twitter Streaming API discontinued XML

6. Google Custom Search API
ee&alt=json {
"kind": "customsearch#search",
"url": {
"type": "application/json",
"template": " },
"queries": {
"request": [
"title": "Google Custom Search - javaee",
"totalResults": "22",
"searchTerms": "javaee",
"count": 10, }

7. JAX-RS XML Usage JAX-RS applications handle XML using JAXP API
@Produces(“application/xml”)
public Source getBook(String id) {
return new StreamSource(…); }

8. JAX-RS Data Binding JAX-RS applications handle XML using JAXB API
@Produces(“application/xml”, “application/json”)
public Book getBook(String id) {
return new Book(…); }
JAX-RS
Book
XML
JAXB
JSON ?

9. JAX-RS JSON implementations for Java json-simple mjson Json-marshaller
Jackson
SOJO
org.json
json
fastjson
json-taglib
Argo
Stringtree
jjson
google-gson
json-io
Flexjson
Json-smart
Jettison

10. JAX-RS JSON Solutions and Limitations
A custom MessageBodyWriter that converts to JSON
JSONObject (Ex: json.org’s API)  JSON
POJO/JAXB  XML  JSON (Ex: using jettison)
POJO/JAXB  JSON (Ex: jackson, EclipseLink, etc)
No standard API
Some solutions have technical limitations
Applications/frameworks need to bundle implementation

11. Standard API Concepts JSR 353: Parsing/processing JSON JSR Forthcoming
Similar to JAXP
Expert group
Oracle, Red Hat, Twitter
Individuals (GreenTea JUG/Wen Shao, Werner Keil, Christian Grobmeier)
Community
JSR Forthcoming
Data binding - JSON text  Java Objects
Similar to JAXB

12. JSR Transparency
Json-processing-spec.java.net open source project
Mailing lists
Archived
Issue Tracker

13. Java API for JSON Processing
Overview – JSR 353
API to parse and generate JSON
Streaming API
Low-level, efficient way to parse/generate JSON
Provides pluggability for parsers/generators
Object Model
Simple, easy-to-use high-level API
Implemented on top of Streaming API
Binding JSON to Java objects forthcoming
Streaming API is much more efficient, no intermediate objects created
Object model API is built on top of Streaming API
Forward-only parser, each parser can be configured with multiple features

14. JSON Processing API Architecture…
App 1
App 2
App N
Object Model API
Streaming API
SPI
Provider

15. Java API for JSON Processing
Streaming API
Parses JSON in a streaming way from input sources
Similar to StaX’s XMLStreamReader, a pull parser
Created using
Json.createParser(…)
Json.createParserFactory().createParser(…)
Parser state events
START_ARRAY, END_ARRAY, START_OBJECT, END_OBJECT, …

16. Java API for JSON Processing
Streaming Parser {
"firstName": "John", "lastName": "Smith", "age": 25,
"phoneNumber": [
{ "type": "home", "number": " " },
{ "type": "fax", "number": " " } ] }

17. Java API for JSON Processing
Streaming API
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }
START_OBJECT

18. Java API for JSON Processing
Streaming API
KEY_NAME
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }

19. Java API for JSON Processing
Streaming API
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }
VALUE_STRING

20. Java API for JSON Processing
Streaming API
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }
VALUE_NUMBER

21. Java API for JSON Processing
Streaming API
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }
START_ARRAY

22. Java API for JSON Processing
Streaming API
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }
END_ARRAY

23. Java API for JSON Processing
Streaming API
{ "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] } JsonParser parser = Json.createParser(request.getReader()); Event event = parser.next(); // START_OBJECT event = parser.next(); // KEY_NAME event = parser.next(); // VALUE_STRING String name = parser.getString(); // "John”

24. Java API for JSON Processing
Streaming API
JsonGenerator
Generates JSON in a streaming way to output sources
Similar to StaX’s XMLStreamWriter
Created using
Json.createGenerator(…)
Json.createGeneratorFactory().createGenerator(…)
Optionally, configured with features
E.g. for pretty printing

25. Java API for JSON Processing
Streaming API
JsonGenerator jg = Json.createGenerator(…); jg. .writeStartArray("phoneNumber") .writeStartObject() write("type", "home") write("number", " ") writeEnd() writeStartArray() write("type", ”work") write("number", " ") writeEnd() .writeEnd(); jg.close();
"phoneNumber": [
{ "type": "home", "number": ” ” },
{ "type": ”work", "number": ” ” } ]
Typesafe mapping

26. Java API for JSON Processing 1.0
Object Model API
JsonObject/JsonArray – JSON object and array structures
JsonString and JsonNumber for string and number values
JsonObjectBuilder – Builds JsonObject
JsonArrayBuilder – Builds JsonArray
JsonReader – Reads JsonObject and JsonArray from input source
JsonWriter – Writes JsonObject and JsonArray to output source

27. Java API for JSON Processing
Object API
Reads JsonObject and JsonArray from input source
i/o Reader, InputStream (+ encoding)
Optionally, configured with features
Uses pluggable JsonParser
// Reads a JSON object
try(JsonReader reader = Json.createReader(io)) {
JsonObject obj = reader.readObject(); }
Typesafe mapping

28. Java API for JSON Processing
Object API
Writes JsonObject and JsonArray to output source
i/o Writer, OutputStream (+ encoding)
Optionally, configured with features. For e.g. pretty printing
Uses pluggable JsonGenerator
Typesafe mapping
// Writes a JSON object
try(JsonWriter writer = Json.createWriter(io)) {
writer.writeObject(obj); }

29. Java API for JSON Processing
JsonObject
Holds name/value pairs and immutable
Name/value pairs can be accessed as Map<String, JsonValue>
JsonObject obj = reader.readObject();
Map<String, JsonValue> map = obj.getValues();
String str = obj.getStringValue(“foo”);
Set<String> names = obj.getNames();

30. Java API for JSON Processing
Configuration
Support configuration of parser/generator features, extensibility
Pretty Printing, Single-Quoted strings
Can be used in streaming & object-model API
Pass in a map
Json.createBuilderFactory(Map<String, ?> config)
Json.createGeneratorFactory(Map<String, ?> config)
Json.createParserFactory(Map<String, ?> config)
Json.createReaderFactory(Map<String, ?> config)
Json.createWriterFactory(Map<String, ?> config)
Typesafe mapping

31. TOGETHER WE CAN MOVE JAVA EE
Amazing JSR Adopters
TOGETHER WE CAN MOVE JAVA EE
FORWARD
Your JUG
here
Overview of program
Significant contribution, incl SDK – example (verbal only) Tic-Tac-Toe from Belgian JUG and note we will see them later on
These are a sampling of past participating JUGs
Reiterate community value
Note their JUG can be on the list
Transition to JSR videoof what this looks like/value of participation

32. Summary
JSON Overview
JAX-RS and JSON
JSR 353
JSON API