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Jruby wrapper for Jackson (and Smile)

README.md

LICENSE applicable to this library:

Apache License 2.0 see http://www.apache.org/licenses/LICENSE-2.0

JrJackson:

a jruby library wrapping the JAVA Jackson jars`

NOTE: Smile support has been temporarily dropped

The code has been refactored to use almost all Java.

There is now a MultiJson adapter added for JrJackson


NEWS

26th October 2013 - Added support to serialize arbitary (non JSON datatypes) ruby objects. Normally the toJava internal metod is called, but additionally to_h, to_hash, to_a and finally to_json are tried. Be aware that the to_json method might invoke a new selialization session and impact performance.


API

JrJackson::Json.load(string, options) -> hash like object
      aliased as parse

By default the load method will return Ruby objects (Hashes have string keys). The options hash respects three symbol keys

  • :symbolize_keys

    Will return symbol keys in hashes

  • :raw

    Will return JRuby wrapped java objects that quack like ruby objects This is the fastest option

  • :use_bigdecimal

    Will return BigDecimal objects instead of Float If used with the :raw option you will get Java::JavaMath::BigDecimal objects otherwise they are Ruby BigDecimal

JrJackson::Json.dump(obj) -> json string
      aliased as generate

The dump method expects that the values of hashes or arrays are JSON data types, the only exception to this is Ruby Symbol as values, they are converted to java strings during serialization. NOTE: All other objects should be converted to JSON data types before serialization. See the wiki for more on this.


Internals

There are two Ruby sub modules of the JrJackson module

JrJackson::Json, this is the general external facade used by MultiJson, and is pure Ruby.

JrJackson::Raw, this is used by the Json module, it is defined in Java with annotations exposing it as a Ruby module with module methods.


Benchmarks

Credit to Chuck Remes for the benchmark and initial investigation when the jruby, json gem and the jackson libraries were young.

I compared Json (java) 1.8, Gson 0.6.1 and jackson 2.2.3 on jruby 1.7.5 and OpenJDK 64-Bit Server VM 1.7.0_25-b30 All the benchmarks were run separately. A 727.9KB string of random json data is read from a file and handled 250 times, thereby attempting to balance invocation and parsing benchmarking.

generation/serialize

                                               user     system      total         real
json mri generate: 250                        12.02       0.00      12.02     ( 12.022)
oj mri generate: 250                           7.18       0.00       7.18     (  7.183)
json java generate: 250                        7.83       0.01       7.84     (  7.289)
gson generate: 250                             5.04       0.00       5.04     (  4.995)
jackson generate: 250                          4.94       0.08       5.02     (  4.811)
jackson generate: 250                          4.85       0.04       4.89     (  4.758)


parsing/deserialize - after jrjackson parsing profiling

                                               user     system      total         real
json mri parse: 250                            8.35       0.02       8.37     (  8.366)
oj mri parse: 250                              6.10       0.13       6.23     (  7.527)

gson parse: 250                               12.02       0.02      12.04     ( 11.774)
json java parse: 250                          10.35       0.01      10.36     ( 10.204)
jackson parse string keys: 250                 5.60       0.00       5.60     (  5.356)
jackson parse string + bigdecimal: 250         5.14       0.01       5.15     (  4.946)
jackson parse symbol keys: 250                 4.16       0.01       4.17     (  3.989)
jackson parse symbol + bigdecimal: 250         3.90       0.03       3.93     (  3.597)
jackson parse raw: 250                         3.08       0.01       3.09     (  2.924)
jackson parse raw + bigdecimal: 250            2.70       0.06       2.76     (  2.493)

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