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JSR-353 : Java API for Processing JSON
Jitendra Kotamraju
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intended for information purposes only, and may not be incorporated
into any contract. It is not a commitment to deliver any material, code,
or functionality, and should not be relied upon in making purchasing
decisions. The development, release, and timing of any features or
functionality described for Oracles products remains at the sole
discretion of Oracle.
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Agenda
?? Overview
?? JAX-RS Usage
?? Standardization
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Overview
?? JSON is a light-weight data exchange format
–? Easy for humans/machines to read and write
–? For e.g.:
{"name":"Bob", "age":20, "phone":["276 1234", "123
4567"]}
?? JSON is used by popular web sites in their RESTful
web services
–? Facebook, Twitter, Amazon, …
–? Twitter Streaming API discontinues XML
JSON
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Overview
JSON usages
?? Policy in Amazon SQS
{
...
"Statement": {
"Effect": "Allow",
"Principal": { "AWS": "123456789012” },
"Action": "sqs:SendMessage",
"Resource": "/987654321098/queue1"
}
}
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Overview
?? Followers in Twitter API
{
"previous_cursor": 0,
"ids": [143206502, 143201767, 777925],
"previous_cursor_str": "0",
...
}
JSON usages
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JAX-RS
?? JAX-RS applications handle XML using JAXP API
XML Usage
@Produces(“application/xml”)
public Source getBook(String id) {
return new StreamSource(…);
}
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JAX-RS
?? JAX-RS applications handle XML using JAXB API
XML Usage
@Produces(“application/xml”)
public Book getBook(String id) {
return new Book(…);
}
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JAX-RS
?? JAX-RS content negotiation
DataBinding
XML
JSON
JAX-RS
Book
@Produces({“application/xml”, “application/json”})
public Book getBook(String id) {
return new Book();
}
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JAX-RS
?? A custom MessageBodyWriter that converts to JSON
–? JSONObject (For e.g. json.org’s API) → JSON
–? JAXB → StAX → JSON (For e.g. using jettison)
–? POJO/JAXB → JSON (For e.g. using jackson, eclipseLink
etc.)
?? No standard API
?? Some solutions have technical limitations
?? Applications/Frameworks need to bundle the libraries
JSON Solutions & Limitations
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Standard API
?? Application can use standard types
?? Leaner, portable applications
Advantages
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Standard API
?? Parsing/Processing JSON
?? Data binding : JSON text <-> Java Objects
?? Two JSRs: Processing/Parsing (JSON-P), Binding
(JSON-B)
–? Similar to JAXP and JAXB
–? Close collaboration between the two
Contents
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Java API for Processing JSON (JSON-P)
?? Streaming API to produce/consume JSON
–? Similar to StAX API in XML world
?? Object model API to represent JSON
–? Similar to DOM API in XML world
?? Align with Java EE 7 schedules
?? JSR Supporters
–? fasterxml.com(Jackson), Doug Crockford(json.org)
JSR-353
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JSR-353 : Status
Source: http://blogs.oracle.com/darcy/entry/pictorial_jcp
Here
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JSR-353 Transparency
?? json-processing-spec java.net open source project is
used for JSR-353
?? Mailing lists:
–? users@json-processing-spec.java.net
–? jsr353-experts@json-processing-spec.java.net
?? Issue Tracker:
–? http://java.net/jira/browse/JSON_PROCESSING_SPEC
Open Source Project
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Resources
?? http://json-processing-spec.java.net
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Q&A
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Parsing API
JSON Grammar
Source: http://json.org
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Parsing API
JSON Grammar
Source: http://json.org
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JSR-353 API
?? API initial proposal to EG
–? Based visitor pattern (similar to ASM, JSR 269 API, …)
–? Works nicely with streaming and tree API
–? Providers plug-in their implementations
Processing API
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JSR-353 API
UML class diagram
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