Listening to Session Events

The OnixS C++ FIX Engine exposes OnixS::FIX::ISessionListener class whose virtual members are called by an instance of OnixS::FIX::Session class as response to a particular event occurred during session life-time.

To be notified about particular session event overwrite appropriate member of OnixS::FIX::ISessionListener class and supply descendant instance to OnixS::FIX::Session's constructor.

The following table describes the meaning of all events exposed by the OnixS::FIX::Session class in terms of of OnixS::FIX::ISessionListener class members.

Method (Event handler)	Description
OnixS::FIX::ISessionListener::onStateChange	Session state is changed.
OnixS::FIX::ISessionListener::onError	Error condition is detected.
OnixS::FIX::ISessionListener::onInboundApplicationMsg	Application-level message is received from the counterparty.
OnixS::FIX::ISessionListener::onInboundSessionMsg	Session-level message is received from the counterparty.
OnixS::FIX::ISessionListener::onOutboundApplicationMsg	Application-level message will be sent to the counterparty. This callback could be used to change fields that are set by the FIX Engine.
OnixS::FIX::ISessionListener::onOutboundSessionMsg	Session-level message will be sent to the counterparty. This callback could be used to change fields that are set by the FIX Engine.
OnixS::FIX::ISessionListener::onResendRequest	Sent application-level message is about to be resent to the counterparty.
OnixS::FIX::ISessionListener::onWarning	Warning condition is detected.

Note:

Session event handling/listening is synchronous operation. For this reason it is recommended to do not perform time-consuming tasks inside event handlers. For the same reason it is not recommended to call from the event handler any Session method that could change Session state.

Example

class SessionStateListener : public ISessionListener
{
public:

    virtual void Listener::onStateChange(
        Session::State newState, Session::State prevState, Session* sn)
    {           
                std::clog 
            << "\nSession's state is changed"
            << ". Previous state was " << Session::state2string(prevState) 
            << ", new state is " << Session::state2string(newState) 
            << std::endl;
        }
};