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https://issues.apache.org/jira/browse/FLINK-20265?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tzu-Li (Gordon) Tai updated FLINK-20265:
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Summary: Extend invocation protocol to allow functions to indicate
incomplete invocation context (was: Extend invocation protocol to allow
functions to indicate incomplete state context)
> Extend invocation protocol to allow functions to indicate incomplete
> invocation context
> ---------------------------------------------------------------------------------------
>
> Key: FLINK-20265
> URL: https://issues.apache.org/jira/browse/FLINK-20265
> Project: Flink
> Issue Type: Sub-task
> Components: Stateful Functions
> Reporter: Tzu-Li (Gordon) Tai
> Assignee: Tzu-Li (Gordon) Tai
> Priority: Major
> Fix For: statefun-2.3.0
>
>
> Currently, users declare the states a function will access with a module YAML
> definition file. The modules are loaded once when starting a StateFun
> cluster, meaning that the state specifications remain static throughout the
> cluster's execution lifetime.
> We propose that state specifications should be declared by the function
> themselves via the language SDKs, instead of being declared in the module
> YAMLs.
> The state specifications, now living in the functions, can be made
> discoverable by the StateFun runtime through the invocation request-reply
> protocol.
> Brief simplified sketch of the extended protocol:
> - StateFun dispatches an invocation request, with states [A, B].
> - Function receives request, but since it requires states [A, B, C, D], it
> responds with a {{IncompleteInvocationContext}} response that indicates state
> values for [C, D] is missing.
> - StateFun receives this response, and registers new Flink state handles for
> [C, D].
> - Finally, a new invocation request with the same input messages, but
> "patched" with new states to contain all values for [A, B, C, D] is resent to
> the function.
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