Store and Forward (SaF)

The Store and Forward (SaF) sub-system buffers data which is locally generated or received over a network connection and which needs to be forwarded to another destination. Destinations are either other inmation components or a MongoDB instance as the final destination.

The buffer can be configured to use volatile main memory or persistent hard disk space, involving different trade-offs.

The following example demonstrates a common usage scenario, involving:

  • One Core archiving IO items, log messages and events

  • One Connector supplying IO items and log messages

  • Some IO items on Connector are not archived

Basic Store and Forward (SaF) example scenario
Figure 1. Basic Store and Forward (SaF) example scenario

IO items only use the SaF sub-system if their archiving is switched on. Without archiving activated, only the realtime channel is used, and only recent data changes are transmitted.

So it is possible to configure IO items in one of these 2 modes

  • Realtime only

  • Realtime and history channel (with SaF)

The realtime channel is optimized for fast data delivery, whereas the history channel is optimized for guaranteed delivery of the data. The Current Lag Time performance counter (Channel Diagnostics Group) gives indication about the performance of the realtime channel.