creating a POC which shows the capability of restfull api implementation for spark jobs .Web ui making call to spark job using restfull api. You can use spark job server manager ,[url removed, login to view] , play 2 or akka-http.
Two main features of POC should be
Have long running SparkContexts that can be used for multiple Spark jobs, by multiple clients
Share cached RDDs or Dataframes across multiple jobs and clients
If play offers this feature i am fine using PLay 2 . Spark and webui can be as simple as you want with few lines of code . Let me know your thoughts and rough estimate