EMAJ: [OmmConsumer batch] Can I dynamiclly change the itemlist during running?

loy.longyi
loy.longyi
in EMA

Regarding sample example370__MarketPrice__Batch

consumer  = EmaFactory.createOmmConsumer(EmaFactory.createOmmConsumerConfig().host("localhost:14002").username("user"));
            
ElementList batch = EmaFactory.createElementList();
OmmArray array = EmaFactory.createOmmArray();
            
array.add(EmaFactory.createOmmArrayEntry().ascii("TRI.N"));
array.add(EmaFactory.createOmmArrayEntry().ascii("IBM.N"));

batch.add(EmaFactory.createElementEntry().array(EmaRdm.ENAME_BATCH_ITEM_LIST, array));
            
consumer.registerClient(EmaFactory.createReqMsg().serviceName("DIRECT_FEED").payload(batch), appClient);

Can I change the content of ENAME_BATCH_ITEM_LIST after registerClient()?

Much appreciated for any suggestion!

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Best Answer

  • pimchaya.wongrukun01
    pimchaya.wongrukun01
    Answer ✓

    Hello @loy.longyi

    If you mean to modify ENAME_BATCH_ITEM_LIST of the batch stream the application has opened (registerClient(..) has called already), based on my test it seems to be impossible. Since batch stream is closed after the batch steam request is sent to the server like the message below:

    Item Name: <not set>
    Service Name: API_ELEKTRON_EPD_RSSL
    Item State: Closed / Ok / None / 'Stream closed for batch'

    Hence, there is no batch stream to be modified. Then, ADS responds by sending the items as if they were opened individually like the diagram below:

    image

    When I tried to modify the batch stream, I got the following error:

    Jan 20, 2020 10:34:22 AM com.thomsonreuters.ema.access.BatchItem modify
    SEVERE: loggerMsg
        ClientName: BatchItem
        Severity: Error
        Text:     Invalid attempt to modify batch stream. Instance name='Consumer_1_1'.
    loggerMsgEnd

    If you want to add new RICs, you have to create a new batch request and call registerClient(..).

Answers

  • wasin.w
    wasin.w admin

    Hello @loy.longyi

    You can not change the subscription RICs on existing item streams as mention by my colleague above.

    You can pause-resume, change subscription View and increase-decrease the streams priority on existing streams with "reissue" function only.

  • pimchaya.wongrukun01
    pimchaya.wongrukun01

    Hello @loy.longyi

    For the example of reissue, please look into example301__MarketPrice__PriorityChange

  • veerapath.rungruengrayubkul
    veerapath.rungruengrayubkul

    Batch Stream will be closed automatically after server receives a batch request. Consumer application will receive item response on individual streams. To remove subscription for an item, the application needs to get handle of item stream via OmmConsumerEvent,handle() in onRefreshMsg(), and then use the handle in the OmmConsumer.unregister() method.

        public void onRefreshMsg(RefreshMsg refreshMsg, OmmConsumerEvent event)
        {
            System.out.println("Handle: " + event.handle());
            System.out.println("Item Name: " + (refreshMsg.hasName() ? refreshMsg.name() : "<not set>"));

    Sample output 

    Handle: 2
    Item Name: TRI.N
    Service Name: XXX
    Item State: Open / Ok / None / 'All is well'
    Fid: 1 Name = PROD_PERM DataType: UInt Value: 6562
    Fid: 2 Name = RDNDISPLAY DataType: UInt Value: 64
    ...
    Handle: 3
    Item Name: IBM.N
    Service Name: XXX
    Item State: Open / Ok / None / 'All is well'
    Fid: 1 Name = PROD_PERM DataType: UInt Value: 62
    Fid: 2 Name = RDNDISPLAY DataType: UInt Value: 64
  • loy.longyi
    loy.longyi

    Pimchaya.Wongrukun

    Thank you for your reply!

    Per ur suggestion, I can create a new batch request and call registerClient(..) to subscribe new RICs, and ignore the ones which I don't need.

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