Thanks Lucas for the KIP. The KIP is already in very good shape and covers the edge cases. I still have a few questions and considerations I’d like to share.
AS01: Are Assignment topology (defined in KIP-1071) and the Description topology (defined in KIP-1331) guaranteed to be consistent views of the same logical topology, or can they drift? Are we guaranteeing that every assignment we surface references only nodes/topics present in the current description topology, or can operators see combinations that don’t line up? AS02: I'm cusrious about the rationale or empirical data behind the 350 KB default (e.g., based on observed real-world topologies)? Also the KIP says the broker measures topology size and rejects oversized payloads with TOPOLOGY_DESCRIPTION_TOO_LARGE. Should the Streams client attempt a best-effort pre-check of the serialized size to avoid repeated failing pushes and log a clearer local error? Or is the intent to keep the client simple and rely entirely on the broker response + plugin behavior for this case? AS03: Why do we introduce a separate Admin-side POJO instead of reusing TopologyDescription from the Streams API—for dependency/semantic reasons? And how do we plan to keep the two representations in sync? AS04: Somewhat related to AS01.... In practice we’ve seen that because members and assignments change so dynamically, a user may see different assignments or members over just a few seconds, or a member with a specific memberId may disappear entirely. Having the topology visible might help users understand what’s going on—but it could also make things more confusing, depending on the situation. AS05: I assume that even with a single plugin, multiple downstream systems can still benefit from it (the plugin can of course fan out to multiple downstream systems). Am I right? Thanks, Alieh On Mon, May 4, 2026 at 11:39 AM Lucas Brutschy via dev <[email protected]> wrote: > Hi all, > > I would like to start the discussion on KIP-1331. The idea is to > optionally make a topology description available to the broker, in the > spirit of KIP-714. Looking forward to your feedback! > > > https://urldefense.com/v3/__https://cwiki.apache.org/confluence/display/KAFKA/KIP-1331*3A*Streams*Group*Topology*Description*Plugin__;JSsrKysr!!Ayb5sqE7!sxqGDUcjOzRpt9Gk0jE1XnVSit-FZMIihk2UsXWUI0jmdYK2nTcO1hP-9WiW5sLBMw8amIUxG2PGvhdRhok$ > > Best, > Lucas >
