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When you are simply reporting values from an industrial controller or similar data source, all the web-displays for all users should show the same values. However, when a request is made from the UI it's possible that the values should be sent only to that display. A common example of this is the display of data from a database. Each user can select their own lookback period and display data unique to them.

Another example is using an on-screen component to cause a popup window to appear, for example asking for additional information. An example of this is in our SECS/GEM data collection solution where, once the user enters a lot-id, they are automatically prompted for an operator Id.

In this case, we want only the application into which the lot-id was entered to prompt for the operator, but all application to be updated with both the lotid and the operator.