How to parse OMMMsg in a simple way

peng.xiaoliang
peng.xiaoliang Newcomer
in RFA

i run the example code ,and receive the next text:

AttribInfo
		ServiceName: ELEKTRON_DD
		ServiceId: 257
		Name: JPY=
		NameType: 1 (RIC)
	Payload: 2081 bytes
		FIELD_LIST
			FIELD_ENTRY 1/PROD_PERM: 213
			FIELD_ENTRY 2/RDNDISPLAY: 153
			FIELD_ENTRY 3/DSPLY_NAME: MDM BANK     MOW
			FIELD_ENTRY 5/TIMACT: 07:31
			FIELD_ENTRY 11/NETCHNG_1: 0.17
			FIELD_ENTRY 12/HIGH_1: 108.91
			FIELD_ENTRY 13/LOW_1: 108.68
			FIELD_ENTRY 15/CURRENCY: JPY (392)
			FIELD_ENTRY 17/ACTIV_DATE: 24 APR 2018
			FIELD_ENTRY 19/OPEN_PRC: 108.69
			FIELD_ENTRY 21/HST_CLOSE: 108.70
			FIELD_ENTRY 22/BID: 108.87
			FIELD_ENTRY 23/BID_1: 108.87
			FIELD_ENTRY 24/BID_2: 108.86
			FIELD_ENTRY 25/ASK: 108.88
			FIELD_ENTRY 26/ASK_1: 108.88
			FIELD_ENTRY 27/ASK_2: 108.89

what i want is like JSON format :

{"CURRENCY": "JPY","BID":"108.87","ASK":"108.88"}

I only want the three Fields "CURRENCY ,BID ,ASK", but the parse way is too hard to understand. I don't know how to fix the code.

Would you please give me a simply way to parse the OMMMsg?

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Best Answer

  • pimchaya.wongrukun01
    pimchaya.wongrukun01 LSEG
    Answer ✓

    Hello @peng.xiaoliang

    RFA Java package provides the GenericOMMParser class which is
    used to read and initialize dictionaries and parse any OMM messages. Hence, you
    may modify GenericOMMParser class to get your preference fields from the response
    and keep them in the map. Then, you can create them as your preference format
    i.e. JSON. The example source code is here:

     //Add the method to GenericOMMParser.java to get CURRENCY, BID and ASK field
        public static HashMap<String,String> parseOMMData(OMMData data)
        {
        	HashMap<String,String> preferredFields = new HashMap<String,String>();
        	String valueStr;
        	if(CURRENT_DICTIONARY==null) 
    	//make sure that RDMdictionary is loaded already
        		CURRENT_DICTIONARY = getDictionary(1);
            for (Iterator iter = ((OMMIterable)data).iterator(); iter.hasNext();)
            {
                OMMEntry entry = (OMMEntry)iter.next();
                if(entry.getType()==OMMTypes.FIELD_ENTRY) {
                	OMMFieldEntry fe = (OMMFieldEntry)entry;
                	FidDef fiddef = CURRENT_DICTIONARY.getFidDef(fe.getFieldId());
                	OMMData aValue = null;
                	if(fe.getFieldId() == 22 || fe.getFieldId()==25) { 
    		//BID or ASK field
                		aValue=  fe.getData(fiddef.getOMMType());
                		if(!aValue.isBlank()) 
    			//not blank value, get value as a String
                			valueStr = aValue.toString();
                		else
                			valueStr = ""; //otherwise, set blank value
                		preferredFields.put(fiddef.getName(), valueStr);
                	}
                	else if(fe.getFieldId() == 15)//CURRENCY which is enum type
                    {
                		aValue=fe.getData(fiddef.getOMMType());
                		if(!aValue.isBlank()) 
    			//not blank value, get String of the enum value 
                			valueStr=CURRENT_DICTIONARY.expandedValueFor((short)15, ((OMMEnum)aValue).getValue());  
                		else
                			valueStr = ""; //otherwise, set blank value
                		preferredFields.put(fiddef.getName(), valueStr);
                    }	
                }
            }
            return preferredFields;
        }
    ...
    //in your application at the method to process data(item events)
    public void processEvent(Event event)
    {
    	...
    	OMMItemEvent ie = (OMMItemEvent)event;
            OMMMsg respMsg = ie.getMsg();
            GenericOMMParser.parse(respMsg);
          //If it is Refresh or Update data message, get data
            if((respMsg.getMsgModelType() == RDMMsgTypes.MARKET_PRICE) && 
            		( respMsg.getMsgType() == OMMMsg.MsgType.REFRESH_RESP || respMsg.getMsgType() == OMMMsg.MsgType.UPDATE_RESP))
            {
            	//Get CURRENCY, BID and ASK field
            	HashMap<String,String> preferredFields= GenericOMMParser.parseOMMData(respMsg.getPayload());
            	//Create JSON format
            	//{"CURRENCY": "JPY","BID":"108.87","ASK":"108.88"}  
            	StringBuffer jsonDataFormatStrBuf = new StringBuffer("{");
            	if(preferredFields.containsKey("CURRENCY"))
            		jsonDataFormatStrBuf.append("\"CURRENCY\":\"" + preferredFields.get("CURRENCY")+"\",");
            	if(preferredFields.containsKey("BID")) 
            		jsonDataFormatStrBuf.append("\"BID\":\""+ preferredFields.get("BID"));
            	if(preferredFields.containsKey("ASK")) 	
            		jsonDataFormatStrBuf.append("\",\"ASK\":\"" + preferredFields.get("ASK") + "\"}");
            	if (jsonDataFormatStrBuf.toString().length() > 1) //contain at least 1 field
            		System.out.println("Json Data format is " + jsonDataFormatStrBuf.toString());	 
            }

    The example Refresh
    message output:

    Msg Type: MsgType.REFRESH_RESP
    	…
    	Payload: 2060 bytes
    		FIELD_LIST
    			FIELD_ENTRY 1/PROD_PERM: 213
    			FIELD_ENTRY 2/RDNDISPLAY: 153
    			FIELD_ENTRY 3/DSPLY_NAME: BARCLAYS     LON
    			FIELD_ENTRY 5/TIMACT: 09:34
    			FIELD_ENTRY 11/NETCHNG_1: 0.20
    			FIELD_ENTRY 12/HIGH_1: 109.26
    			FIELD_ENTRY 13/LOW_1: 108.80
    			FIELD_ENTRY 15/CURRENCY: JPY (392)
    			FIELD_ENTRY 17/ACTIV_DATE: 25 APR 2018
    			FIELD_ENTRY 19/OPEN_PRC: 108.80
    			FIELD_ENTRY 21/HST_CLOSE: 108.81
    			FIELD_ENTRY 22/BID: 109.01
    			FIELD_ENTRY 23/BID_1: 109.02
    			FIELD_ENTRY 24/BID_2: 109.02
    			FIELD_ENTRY 25/ASK: 109.04
    			FIELD_ENTRY 26/ASK_1: 109.04
    			FIELD_ENTRY 27/ASK_2: 109.04
    …
    Json Data format is {"CURRENCY":"JPY","BID":"109.01","ASK":"109.04"}

    The example Update
    message output:

    	Msg Type: MsgType.UPDATE_RESP
    	…
    	Payload: 212 bytes
    		FIELD_LIST
    			FIELD_ENTRY 22/BID: 109.02
    			FIELD_ENTRY 393/PRIMACT_1: 109.02
    			FIELD_ENTRY 25/ASK: 109.05
    			FIELD_ENTRY 275/SEC_ACT_1: 109.05
    			…
    Json Data format is {"BID":"109.02","ASK":"109.05"}

    Note: an Update message
    contains only change fields so CURRENCY may not in the Update message.

    If you would like to get
    only your preference fields(CURRENCY, BID and ASK) from the server which is ADS(one
    component of TREP), you can use Dynamic View feature which allows ADS sends
    only fields specified in the request message to your application. For more
    details and example application, please refer to How to request particular fields of an item (RIC) via RFA API

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