Similarities to Knative Serving

I happened to find the Knative Serving documentation and it appears that this is a very similar concept to what I have been suggesting.

https://github.com/knative/docs/tree/master/serving

Note: I have adapted the entry point in the system to be an Istio Virtual Service instead of an Envoy Filter.

In the above diagram, the red and green boxes show the boundary of a proposed "service graph"

Below, imagine a system that has several services that use a stateful component.  This component has a method getMax that returns the maximum value of all the values it has processed.  If only one service in the graph has updated data that results in a new getMax value; then it will be the only one in the graph of related services to return the new value.  If your system depends on consistent results across a set of interrelated services this could be a problem.  This could be handled using synchronization logic inside of the individual services but another approach could be to keep service graphs consistent per snapshot.