6 - Processing Responses

When the Logger processes a command, it generates internal responses indicating state changes (for example, file opened).

It also sends these responses to the network, where the remote control interface receives them. The responses are domain specific and the remote control interface forwards them to the appropriate domain interface. The domain interfaces unify the separate Logger responses into a single response call after receiving one from each connected Logger. In some cases, a response indicates a failure condition (for example, file invalid when expecting file opened). Failure responses are invoked separately for each Logger and they may short circuit an expected response. The responses may modify the domain interfaces state information to reflect the reported state changes (for example, filename, firstTime, lastTime). The state changes can alter the behavior of the interfaces to allow or not allow a given command to become active (for example, play is not active until a fileOpened response has been received). When a command is not active, it returns a sequence number of 0. The state information may be inspected at any time.

Handling Responses

The remote control application can process the responses by overriding the appropriate method in the domain specific interface. The method override must make a call to the base class method so that it can perform its operation first.

void DtPlaybackInterfacePrinter::fileOpened( const DtString& fileName, const DtAbsoluteTime& firstTime, const DtAbsoluteTime& lastTime)
{
   DtRemoteControlPlaybackInterface::fileOpened(
      fileName, firstTime, lastTime);
   DtInfo << "All Loggers report fileOpened: " << fileName << " first:
      " << firstTime << " last: " << lastTime << std::endl;
}

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