You should use Dynamic View feature that allow you to specific filed entries of an item. The request with a view specification will receive a response message that contains only those entries defined by the requested view.
However, ADS your application connects to must have installed the required license (the SNAP_AND_DYNAMIC_VIEW license key) to enable the feature as well.To obtain the licenses for ADS, please contact your Thomson Reuters Account Manager.
Programming with View in RFA Java is explained in section 13.3 Views of RFA Java Developers Guide(RFAJ_DeveloperGuide.pdf). How to specify fields is in section 220.127.116.11 Creating Request Message With View. The example application using View is StarterConsumer_BatchView located in <RFAJ package>\Examples\com\reuters\rfa\example\omm\batchviewcons.
Here is an example command to subscribe MARKET_PRICE data of TRI.N with only BID (FID 22), ASK (FID 25) and TRDPRC_1 (FID 6) fields.
java com.reuters.rfa.example.omm.batchviewcons.StarterConsumer_BatchView -session myNamespace::consSession -serviceName API_ELEKTRON_EPD_RSSL -rdmFieldDictionary ..\etc\RDM\RDMFieldDictionary -enumType ..\etc\RDM\enumtype.def -mmt MARKET_PRICE -itemName TRI.N -sendView true -viewType 1 -viewData 6,22,25 -sendReissue false -reissueWithPAR false -reissueWithPriority false
This following output is showing the result from the example command above.
Further information about StarterConsumer_BatchViewapplications, please refer to package.html file which is located in the source folder of the example.