title: OPC UA server historical access support
body: <p>We are looking for a solution for collecting data from different SCADA systems. It seems that OPC UA is a good approach for that. Data collection will be done from a single system to multiple SCADA systems over the internet (https). So, we are planning to develop a OPC UA client that can connect to multiple OPC UA servers. Data will be collected with a given interval. The system should be able to handle if the connection between client and server is lost for a period of time. In that case, I assume we need to get the data by looking into historical data. Hence, we need a server that support HA (Historical Access).
  Are there any servers supporting this or do we need to develop our own server implementation?
  Or is there a better approach than the one described above?
  Any help or hints on this would be appreciated.</p>