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michael.watrous avatar image
3 ●0 ●2 ●3

Getting A18: Unknown service when using websockets to subscribe to MRN_STORY

I am trying to use the websocket example t mrn_console_app.py python script to subscribe to MRN_STORY from our internal TREP infrastructure. I am able to subscribe to a websocket enabled ads using the following rmdstestclient command:

rmdstestclient -h ncmdplm13202-364.dc.gs.com -S IDN_RDF -u BGS -md 33 -itemList MRN_STORY -d 3 -X -dfile $SC/RDMFieldDictionary.GS -l stdout

PROD_PERM : UINT 2 : [10001]

ACTIV_DATE : DATE 4 : [14 MAY 2022]

RECORDTYPE : UINT 1 : [30]

RDN_EXCHD2 : ENUM 2 : [1370]

TIMACT_MS : UINT 4 : [59114397]

GUID : STRING 0 : []

CONTEXT_ID : REAL 3 : [3752]

DDS_DSO_ID : UINT 2 : [8328]

SPS_SP_RIC : STRING 10 : [.[SPSML0L1]

MRN_V_MAJ : STRING 1 : [2]

MRN_TYPE : STRING 5 : [STORY]

MDU_V_MIN : UINT 0 : []

MDU_DATE : DATE 0 : []

MRN_V_MIN : STRING 2 : [10]

MRN_SRC : STRING 9 : [HDC_PRD_A]

MDUTM_NS : TIME 0 : []

FRAG_NUM : UINT 1 : [1]

TOT_SIZE : UINT 1 : [0]

FRAGMENT : STRING 0 : []


When I try to do it with the webscoket example I see that I am setting the service correctly from the initial output:

SENT:

{

"Domain":"Login",

"ID":1,

"Key":{

"Elements":{

"ApplicationId":"256",

"Position":"10.50.92.16"

},

"Name":"XXX",

"Service":"IDN_RDF"

}

}

RECEIVED:

[

. . .


"State":{

"Data":"Ok",

"Stream":"Open",

"Text":"Login accepted by host ncmdplm13202-364.dc.gs.com."

},

"Type":"Refresh"

}

]

but the subscription closes with:

RECEIVED: Status Message

{

"Domain":"NewsTextAnalytics",

"ID":2,

"Key":{

"Name":"MRN_STORY",

"Service":0

},

"State":{

"Code":"SourceUnknown",

"Data":"Suspect",

"Stream":"Closed",

"Text":"A18: Unknown service."

},

"Type":"Status"

}

What am I doing wrong? Note that I am able to succefully subscribe to a MarketByPrice domain instrument (e.g. INTC.O) from this same ads using webscokets

Thanks


websocketsnewsrmds-test-clientnews-text-analytics
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wasin.w avatar image   wasin.w

Hello @michael.watrous

Thank you for your participation in the forum. Is the reply below satisfactory in resolving your query?


If so please can you click the 'Accept' text next to the appropriate reply? This will guide all community members who have a similar question.

Thanks,


AHS

2 Answers

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zoya faberov avatar image
32.2k ●40 ●11 ●20

Hello @michael.watrous ,

Are you including SERVICE in MRN request? If not, try adapting the example code like this: 

def send_mrn_request(ws):
    """ Create and send MRN request """
    mrn_req_json = {
        'ID': 2,
        "Domain": mrn_domain,
        'Key': {
            'Name': mrn_item,
            "Service":"IDN_RDF"
        }
    }

Let us know how this works on your side

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michael.watrous avatar image michael.watrous
This worked great. Thanks.
Upvote
wasin.w avatar image
24.6k ●54 ●17 ●14

Hello @michael.watrous

The WebSocket API request message basic structure is the following:

{
  "ID":<int>,
  "Domain" : "Domain Name"
  "Key":{
    "Name":"<RIC Code>"
    "Service": "Service Name"
  }
}
  • If the JSON message does not contain the "Domain" attribute, it will default to "MarketPrice"
  • The "Service" attribute is an optional parameter. If absent, the ADS will use the service defined in ADS' *ads*defaultJsonServiceId configuration.

The Status "Text": "A18: Unknown service." means the Service ID value in ads*defaultJsonServiceId configuration is not the correct Service ID or did not set. If the ADS cannot find the service for the request message, it sends this error message to the application.

I suggest you add the service name to the JSON request message as suggested by my colleague @zoya faberov.

Alternatively, you can check if the ads*defaultJsonServiceId parameter is configured to the correct Service ID.

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