json mapper

[Peter Ertl]

Hi flink users,

I just wanted to ask if this kind of scala map function is correct?

object JsonMapper {
  private val mapper: ObjectMapper = new ObjectMapper()
}

class JsonMapper extends MapFunction[String, ObjectNode] {
  override def map(value: String): ObjectNode = 
JsonMapper.mapper.readValue(value, classOf[ObjectNode])
}

Is using a static reference to ObjectMapper fine or will this cause issues on a 
distributed cluster / with checkpoint / serializing state / whatever ?

Or should I instead use a non-transient property initialized in ctor 
(ObjectMapper is java.io.Serializable) ?

Or should I initialize it with RichMapFunction.open into a transient property?

Also I am wondering if replacing 'class' with 'object' (=> singleton)

object JsonMapper extends MapFunction[String, ObjectNode] { /* ..*/ }

is ok (actually the mapper is stateless so no obvious need to re-instantiate it 
again and again ? )

Thanks and best regards
Peter