Can my application request the same RIC multiple times?

mark.ringrose1
mark.ringrose1
in EMA

I have a question about what happens if my application requests the same RIC multiple times. What happens? Will the API warn me that I already have it? What should I do to check or guard against this happening? I saw this article (link) but it didn't answer my question. Thank you. API is EMA Java v4.1.


https://community.developers.refinitiv.com/questions/10057/subscribing-to-ric-multiple-times.html

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Best Answer

  • zoya faberov
    zoya faberov
    Answer ✓

    Hello @mark.ringrose,

    For EMA this is a valid request, so there will be no warning. EMA will establish two streams on behalf of the consumer, each with it's own streamId. The consumer will process every update twice, once on each stream ID, so if one is printing the updates, each update will be seen twice.

    For example:

    UpdateMsg
        streamId="5"
        domain="MarketPrice Domain"
        updateTypeNum="0"
        name="JPY="
        serviceId="300"
        serviceName="ELEKTRON_EDGE"
        Payload dataType="FieldList"
            FieldList
                FieldEntry fid="114" name="BID_NET_CH" dataType="Real" value="0.47"
                FieldEntry fid="372" name="IRGPRC" dataType="Real" value="0.44"
            FieldListEnd
        PayloadEnd
    UpdateMsgEnd

    EmaRdm.INSTRUMENT_UPDATE_UNSPECIFIED
    UpdateMsg
        streamId="6"
        domain="MarketPrice Domain"
        updateTypeNum="0"
        name="JPY="
        serviceId="300"
        serviceName="ELEKTRON_EDGE"
        Payload dataType="FieldList"
            FieldList
                FieldEntry fid="114" name="BID_NET_CH" dataType="Real" value="0.47"
                FieldEntry fid="372" name="IRGPRC" dataType="Real" value="0.44"
            FieldListEnd
        PayloadEnd
    UpdateMsgEnd

    If you would prefer for this not to happen, at the point of registerClient, would check if the subscription is unique.

    Does this address the question?

Answers

  • mark.ringrose1
    mark.ringrose1

    Zoya,


    Thank you very much for your prompt reply. It does address the question. One further question on your reply: In your final sentence you say: "If you would prefer for this not to happen, at the point of registerClient, would check if the subscription is unique."

    Does the registerClient method respond with a flag or indicator to tell me if the subscription is unique? So, do I just have to check this flag or do I need to do something special to find out if the subscription is unique?

    Thank you.

  • zoya faberov
    zoya faberov

    @mark.ringrose,

    Each subscription returns a handle. Please look up registerClient() and handle(), in Reference.

    Each event carries the handle, i.e. event.handle, so one can match the two, the registration and the event, this way. The intention of the handle:

    • is to match the event seen in a callback with subscription
    • to unregister
    • to reissue
    • not to determine if it is unique in terms of item

    In order not to register for the same item twice, the consumer keeps track of and controls what it passes into registerClient

    Please note that one may also require register for two of the same item with different Domain Model, i.e. L1 and L2, which is also a legit use, and will result in two different handles with two different streamIds.

    Please note, that one can pass parameter closure into registerClient that may help keeping track of uniqueness, among other things. If we generate a closure in a way that uniquely defines every item registration, and store and keep the closures that have been used prior, we can always check if the registration is unique.

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