Optimize Jackson extension performance

[jlouvel]

We should facilitate the reuse of expensive objects such as ObjectMapper.

See this discussion thread: http://restlet.tigris.org/ds/viewMessage.do?dsForumId=4447&dsMessageId=3044375

Some references: http://wiki.fasterxml.com/JacksonBestPracticesPerformance https://github.com/Tembrel/restlet-misc/blob/master/src/main/java/net/peierls/restlet/misc/LocalJacksonConverter.java

[qsiebers]

For those running into this:

My current solution is to create a ConverterService subclass that calls JacksonRepresentation.setObjectMapper, JacksonRepresentation.setObjectReader and JacksonRepresentation.setObjectWriter with pre-configured (reused) versions.

I think the main hurdle to solve this in the restlet code base is that the JacksonRepresentation.createObjectMapper method create a different ObjectMapper per MediaType, which makes it hard to reuse it.

[Tembrel]

For an alternative that doesn't involve subclassing ConverterService (but does involve subclassing JacksonConverter), check out this example from nearly six (!) years ago:

https://github.com/Tembrel/restlet-misc

That example is in the context of dependency injection, but the basic idea of subclassing JacksonConverter and registering the subclass with the Restlet engine can be applied anywhere.

[qsiebers]

@Tembrel Yes, I've applied that approach before here.