Best practice for accessing known fields

anthony.leon

I am migrating from TibMsg to OMM. Our application just needs numerical data (e.g. BID, ASK). So being new to
OMM I would like you advice.

1. Is there a more direct method to get fields?
2. Considering that I know the field and data type in advance, is the code below too defensive? Not defensive
   enough?

public void processEvent(Event event) { 
  if (event.getType() == Event.COMPLETION_EVENT) { 
    log.info("Receive a COMPLETION_EVENT, "+ event.getHandle()); 
    return; 
  } 
  if (event.getType() != Event.OMM_ITEM_EVENT) { 
    log.warning("Received an unsupported Event type."); 
    mainApp.disconnect(); 
    return; 
  } 
  OMMItemEvent ie = (OMMItemEvent) event; 
  OMMMsg respMsg = ie.getMsg(); 

  if (respMsg.getDataType() != OMMTypes.NO_DATA) { 
    OMMData ommPayload = respMsg.getPayload(); 

    if (ommPayload.getType() == OMMTypes.FIELD_LIST) { 
      OMMFieldList ommFieldList = (OMMFieldList) ommPayload; 
      int dictId = ommFieldList.getDictId(); 
      FieldDictionary fd = GenericOMMParser.getDictionary(dictId); 

      for (Iterator<OMMEntry> it = ommFieldList.iterator(); it.hasNext(); ) { 
        OMMEntry ommEntry = it.next(); 

        if (ommEntry.getType() == OMMTypes.FIELD_ENTRY) { 
          OMMFieldEntry ommFieldEntry = (OMMFieldEntry) ommEntry; 
          FidDef fidDef = fd.getFidDef(ommFieldEntry.getFieldId()); 
          String field = fidDef.getName(); 

          if (field.equals("BID") || field.equals("ASK")) { 
            OMMData actualData = ommFieldEntry.getData(fidDef.getOMMType()); 
            double d = ((OMMNumeric) actualData).toDouble(); 
            System.out.printf("Field [%1$s] Value [%2$f]\n", field, d); } 
          } // field_entry
       } // iterator 
     } // field list 
  } // no_data 
}

Sarit Chantasuban

I've tried the code and it worked well. This is a typical and direct way to retrieve fields in OMM so I don't think there is a more direct way for this. And, I don't see any need to perform further defensive type checking - it was sufficient for the task.

Steven McCoy

If not using a "dynamic view" one can see a performance improvement by breaking out from the field enumeration once all desired fields have been extracted.