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IProvider downloading dictionary and serviceName\serviceId parameter

Hi, I'm trying to implement the Dictionary downloading mechanism in an EMA C++ Interactive Provider.
To do so, I'm playing with the '350__Dictionary__Streaming' example of the EMA SDK.
I have a question regarding the following instruction: provider.registerClient(ReqMsg().name("RWFFld").filter(DICTIONARY_NORMAL).serviceName("DIRECT_FEED").domainType(MMT_DICTIONARY), appClient);
As far as I understood, any client registration in EMA where the serviceName is specified, requires that EMA knows such service in advance, otherwise the operation is rejected. For instance, a consumer that registers a client for a MarketPrice item on the service DIRECT_FEED will be able to perform the request only if the required info about the DIRECT_FEED service has been received previously on the DIRECTORY domain.
So my question is: where does the IProvider get this information to register a client on the MMT_DICTIONARY domain and specifying the service name?
So far, the only way I found to make EMA see the service is to declare the service among the ones provided by the IProvider itself. If I don't do it, EMA does not accept the registerClient(...) requests using that service, and a status message is received with text "Closed / Suspect / Source unknown / 'Service name of 'DIRECT_FEED' is not found.'".
Ps: to make some tests, I connected an ETA based NIProvider (able to handle dictionary requests) to my IProvider. I understand that this isn't a real use case, hoping that it isn't the root cause of my issue..
By the way, if I make the dictionary requests without specifying the service, and edit the NIProvider to send refresh without specifying the service, everything works well.

Please help me clarifying this.



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1 Answer

11.3k 25 8 14

Hi @Paolo Parlapiano

I also cannot find a way for EMA IProvider to get service information available on connected ADH. Also as you mentioned, EMA allows only service that it have information to be registered, so, in this scenario, the application can only use the service name declared in DIRECTORY response sent by provider side.

I have also tested the dictionary request to ADH without service name specified, ADH can provide dictionary properly. From my understanding, this feature is to download dictionary from ADH component, not service.

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Thank you for the analysis.