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Module watch

haystack_server::ops

Module watch 

Source
Expand description

Watch ops — subscribe, poll, and unsubscribe for entity changes.

§Overview

The watch ops allow clients to track changes to a set of entities. A watch is created via watchSub, polled via watchPoll, and torn down via watchUnsub.

§watchSub (POST /api/watchSub)

§Request

Grid meta may contain watchId (Str) to add IDs to an existing watch. Rows contain:

ColumnKindDescription
idRefEntity to subscribe to

§Response

Grid meta contains watchId (Str). Rows are the current state of each subscribed entity (one column per unique tag).

§watchPoll (POST /api/watchPoll)

§Request

Grid meta must contain watchId (Str). No rows required.

§Response

Rows are entities that changed since the last poll. Empty grid if no changes occurred.

§watchUnsub (POST /api/watchUnsub)

§Request

Grid meta must contain watchId (Str). Rows may contain id (Ref) to selectively remove entities. If no rows are present, the entire watch is deleted.

§Response

Empty grid on success.

§Errors

  • 400 Bad Request — missing id rows, missing watchId in meta, or request decode failure.
  • 404 Not Found — watchId does not exist or caller is not the owner.

Functions§

handle_poll
POST /api/watchPoll — poll for changes since last poll.
handle_sub
POST /api/watchSub — subscribe to entity changes.
handle_unsub
POST /api/watchUnsub — unsubscribe from a watch.