Subscribing to RIC multiple times

I have a subscription to a set of RICs (e.g. VOD.L) open which processes deltas and populates a cache

Another operation we want to support is the ability to do an AdHoc market data request for a RIC to get a snapshot in time.

If I request VOD.L for an AdHoc snapshot, while our cache service is running (processing changes to existing subscriptions (inc. VOD.L)), no event is received, but if I do an AdHoc request for a RIC we are not currently subscribing to then it will produce a result.

Is it not possible then to request for a RIC while already subscribing to it?

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Accepted answers

Lars-at-Addicticks

Yes, I believe the RFA library will not let you do two subscriptions on the same item.

I suppose by AdHoc you mean snapshot? What you can do is to ask for a REFRESH on the existing stream. This would give you a snapshot-within-the-stream, so to speak.

The way to do that is to call OMMConsumer.reissueClient(...) method.

Here's how it will work using a real-life example:

1. Configure TRexplorer to use message tracing as described here.

2. Open a subscription in streaming mode. In this example I use "EUR=". Streaming mode is simply the same as not ticking "Snapshot". In the Item Viewer you'll now see the data item continuously updating. You'll notice that with every update only some fields actually change.

3. Press the "Refresh" button as indicated below.

4. Watch what happens in the Item Viewer when Refresh button is pressed: all fields are updating.

5. Check the exchanged messages in the Output Window. You'll see a message like the one below:

Every time you press the "Refresh" button you'll get a REFRESH_RESP message. You'll notice in the message it says that the refresh was solicited, meaning you asked for it explicitly. (yes, there's also such a thing as an unsolicited refresh, typically happens after an outage has restored itself)

The above is what it will look like in your application too.

All comments

Lars-at-Addicticks

Yes, I believe the RFA library will not let you do two subscriptions on the same item.

I suppose by AdHoc you mean snapshot? What you can do is to ask for a REFRESH on the existing stream. This would give you a snapshot-within-the-stream, so to speak.

4. Watch what happens in the Item Viewer when Refresh button is pressed: all fields are updating.

5. Check the exchanged messages in the Output Window. You'll see a message like the one below:

The above is what it will look like in your application too.

tina.murthy

Can you please tell me which API you are using. I just tested with RFA C++, and I do get a streaming response followed by a non streaming response. I modified the starterConsumer example. Here is a snippet of my output:

2016 Nov 25 12:37:56.678 ST GMT-06:00 199C 3C7C 608 TRACE <- Received MMT_MARKET_PRICE Refresh TRI.N

serviceName : ELEKTRON_DD

symbolName : TRI.N

streamState : Open

2016 Nov 25 12:38:21.410 ST GMT-06:00 199C 3C7C 608 TRACE <- Received MMT_MARKET_PRICE Refresh TRI.N

serviceName : ELEKTRON_DD

symbolName : TRI.N

streamState : NonStreaming

Lars-at-Addicticks

Information you ask for is already in OP's tags. :-)

Ethan Wong

Using the RFA Java API

I can't seem to get a response if I request a duplicate RIC on an existing consumer

Ethan Wong

How can we go about asking for a REFRESH message with an existing request?

Lars-at-Addicticks

@ethanwong. I've updated my anwer.

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