thenativeweb/cqrs

documentation for cqrs modules and libraries

cqrs's Issues

View models: sequential processing, discovering (and fixing) "holes" in events

I have some questions regarding the view model "side" of CQRS in your libraries. Let's use the sample app as an example.

I'm using the term "view model" here in the CQRS sense, but it may involve "denormalizer" and "view model" (and possibly even some other libs?) since I am not yet sure what their respective responsibilities and boundaries are.

Suppose the following commands are executed in the following order:

• Item A created (1)
• Item A updated (2)
• Item B created (3)

On the view model, do the libraries support globally sequential processing of these events, so that for example (3) is guaranteed to execute after (2)?

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Let's say there has been a network partition or the view model has been down for a while. In the meanwhile, the following events have been written:

• Item A updated (4)
• Item C created (5)

How can the view model detect this situation and catch up?