Also i need more guidance on issue of differentiating data read from different socket

[jpn]

You should cast the QObject pointer to an appropriate type.
Eg.

QTcpSocket* socket = dynamic_cast<QTcpSocket*>(sender());
if (socket)
{
    // do something
}

QTcpSocket* socket = dynamic_cast<QTcpSocket*>(sender());
if (socket)
{
    // do something
}

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And how about something like this for the data storage:

QHash<int, HistoryData>
// where int is QTcpSocket::socketDescriptor()
// and HistoryData is any storage you decide to use, eg. QStringList

QHash<int, HistoryData>
// where int is QTcpSocket::socketDescriptor()
// and HistoryData is any storage you decide to use, eg. QStringList

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