EMA C++ RDM Usage Guide : 3 Login Domain : 3.2 Usage : 3.2.12 Login Generic Message Use
 
3.2.12 Login Generic Message Use
3.2.12.1 RTT Login Generic Message
A Round Trip Time (RTT) Login Generic Message exchange is initiated by the Interactive Provider application. This message must contain the Ticks count, which is set by the provider before sending the message to a consumer that supports RTT functionality. The CPU tick count can be retrieved using the {getTicks} call. When the consumer receives the RTT message, the consumer automatically sends it back to the interactive provider with the Ticks value unchanged. The interactive provider calculates the round trip time by subtracting the Ticks value from the message from its current time given by the {getTicks} call. In its subsequent RTT requests to the consumer, a provider can include the previously calculated RoundTripLatency value, in microseconds.
Handling RTT Login Generic messages on the provider’s side should be implemented in the user application. On the consumer side, the Watchlist automatically mirrors the provider’s RTT request back to the provider when RTT handling is configured. The consumer can listen for these messages and implement specific business-logic to further handle them.
 
Table 12: RTT Login Generic Message Member Use  
COMPONENT
DESCRIPTION / VALUE
DomainType
Required. MMT_LOGIN = 1
PartNum
Not used.
SeqNum
Not used.
SecondarySeqNum
Not used.
PermissionData
Not used.
extendedHeader
Not used.
ServiceId
Not used.
NameType
Not used.
Name
Not used.
Filter
Not used.
Identifier
Not used.
Attrib
Not used.
Payload
Required. Payload is sent as an ElementList type and must contain an ElementEntry with the ticks count that represents the time on the provider’s side. Additionally, Payload can contain two optional entries: RoundTripLatency and TcpRetrans. For further details, refer to Section 3.3.2.