question: public Tuple read ( ) throws IOException { try { Map fields = jsonTupleStream . next ( ) ; if ( fields == null ) { Map m = new HashMap ( ) ; m . put ( "EOF" , true ) ; return new Tuple ( m ) ; } else { String msg = ( String ) fields . get ( "EXCEPTION" ) ; if ( msg != null ) { HandledException ioException = new HandledException ( msg ) ; throw ioException ; } if ( trace ) { fields . put ( "_CORE_" , this . baseUrl ) ; if ( slice != null ) { fields . put ( "_SLICE_" , slice ) ; } } if ( fieldMappings != null ) { fields = mapFields ( fields , fieldMappings ) ; } return new Tuple ( fields ) ; } } catch ( HandledException e ) { throw new IOException ( "--> " + this . baseUrl + ":" + e . getMessage ( ) ) ; } catch ( Exception e ) { throw new IOException ( "--> " + this . baseUrl + ": An exception has occurred on the server, refer to server log for details." , e ) ; } }
target:  Reads a Tuple from the stream. The Stream is completed when Tuple.EOF == true.