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Update documentation for Zenoh timestamping configuration #889

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Update documentation for Zenoh timestamping configuration #889

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611e675
WIP: update documentation for Zenoh timestamping configuration
jordanburklund Jan 8, 2026
084d8f8
Update docs/design.md and clarify timestamping requirement in configs
JEnoch Jul 22, 2026
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3 changes: 2 additions & 1 deletion docs/design.md
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Expand Up @@ -524,7 +524,8 @@ Here is an incomplete list of some of the settings and the values that they can
* `DEPTH` - The maximum number of samples to keep; this only comes into play when `KEEP_LAST` history is used. If `DEPTH` is set to 0, `rmw_zenoh_cpp` will choose a depth of 42.
* `DURABILITY`
* `VOLATILE` - Samples will only be delivered to subscriptions that are active at the time of publishing. This is the `SYSTEM_DEFAULT` durability.
* `TRANSIENT_LOCAL` - "Late-joining" subscriptions will receive historical data, along with any new data. In `rmw_zenoh_cpp`, this is implemented for publishers via the activation of a cache on the `AdvancedPublisher`. On the subscription side the `AdvancedSubscriber` is configured to query this cache to retrieve the historical data.
* `TRANSIENT_LOCAL` - "Late-joining" subscriptions will receive historical data, along with any new data. In `rmw_zenoh_cpp`, this is implemented for publishers via the activation of a cache on the `AdvancedPublisher`. On the subscription side the `AdvancedSubscriber` is configured to query this cache to retrieve the historical data.
**Note**: Zenoh timestamping has to be enabled by configuration in case of `TRANSIENT_LOCAL`+`BEST_EFFORT` publishers. This allows an `AdvancedSubscriber` to reorder historical data and live publications received at the same time, before delivery to the callback API. `TRANSIENT_LOCAL`+`RELIABLE` `AdvancedPublishers` are configured with `miss_sample_detection` which adds a sequence number to each publication for reordering and detection of missing samples.
* `LIVELINESS`
* `AUTOMATIC` - The "liveliness" of an entity of the system is managed by the RMW layer. This is the only `LIVELINESS` that `rmw_zenoh_cpp` supports.
* `MANUAL_BY_TOPIC` - Not supported. It is up to the application to periodically publish to a particular topic to assert liveliness.
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4 changes: 2 additions & 2 deletions rmw_zenoh_cpp/config/DEFAULT_RMW_ZENOH_ROUTER_CONFIG.json5
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Expand Up @@ -206,8 +206,8 @@
/// Whether data messages should be timestamped if not already.
/// Accepts a single boolean value or different values for router, peer and client.
///
/// ROS setting: PublicationCache which is required for transient_local durability

@jordanburklund jordanburklund Jan 8, 2026

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I wasn't sure what to replace this with, so I left it as a WIP and will update it based on feedback from the maintainers.

/// only works when time-stamping is enabled.
/// ROS setting: timestamping is required for TRANSIENT_LOCAL + BEST_EFFORT publishers.
/// See rmw_zenoh_cpp/docs/design.md - "Quality of Service" chapter - for details.
enabled: { router: true, peer: true, client: true },
/// Whether data messages with timestamps in the future should be dropped or not.
/// If set to false (default), messages with timestamps in the future are retimestamped.
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4 changes: 2 additions & 2 deletions rmw_zenoh_cpp/config/DEFAULT_RMW_ZENOH_SESSION_CONFIG.json5
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Expand Up @@ -216,8 +216,8 @@
/// Whether data messages should be timestamped if not already.
/// Accepts a single boolean value or different values for router, peer and client.
///
/// ROS setting: PublicationCache which is required for transient_local durability
/// only works when time-stamping is enabled.
/// ROS setting: timestamping is required for TRANSIENT_LOCAL + BEST_EFFORT publishers.
/// See rmw_zenoh_cpp/docs/design.md - "Quality of Service" chapter - for details.
enabled: { router: true, peer: true, client: true },
/// Whether data messages with timestamps in the future should be dropped or not.
/// If set to false (default), messages with timestamps in the future are retimestamped.
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