websocket websocket webinar webinar elektron websocket api websockets api elektron api edp python authentication websocket api market data sample request ewa websockets connection trep posting api batch snapshot ert in cloud python api cloud license websocket java connectivity login error refresh ADS marketbyorder trep elektron aws webscoket ert disconnect documentation streaming node.js Service state historical conflation analytics market status symbology streamstate dds_trce fields keys OMM deniedbysrc performance tsa delayed error message marketprice exception wss composite exchange codes c# .net ric api call date erp api-key ws fx sso test access reuters api rmtes client 502 c# caching address error code 400 failure MarketFeed unable redundancy domain authhostname post dds testing sink_driven_src eikon bid csharp economic indicators realtime web api status time and sales elektron connect fx rate web sockets json eap news analytics override trkd websockets java streaming qos historical data access trkd streaming news symbol subscriptions suspect api requests descriptions connection closed json access denied trkd posting websockets timeout webscoket api failover login #python key ric composite synchronous production url bad gateway c# .net api limitation credentials error 400 websockets post trep api batchrequest view ric multiple samples record creation and updating. authentication token port ews token mitch contribution simplified stream websock partial level 2 chain ric elektron_dd tick ask websocket android rfa java phyton ezd real-time-data .net approval