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Recovery Models

Roadmap concept, introduced with Partition Tolerance
The current developer preview does not expose a recovery or consistency model for each Cell. Today, Cells declare capability tags. Recovery models are the future declaration axis for authority and recovery behaviour.

A recovery model answers how a Cell should behave when the swarm is partitioned or its serving Node disappears.

Consistent​

Consistent declares that the Cell must not diverge. It may become unavailable when a majority of its voter set cannot be reached.

Its additional configuration includes:

  • an odd replica band,
  • an action to take after failure.

A Consistent Cell can range from one unreplicated instance to a replicated deployment. Replicated data arrives later with Durability.

Convergent​

Convergent declares that segments may diverge and later reconcile under a defined merge rule.

Availability and merge behaviour are not current guarantees. A defensible merge model belongs to the Secure Swarm roadmap stage and must be demonstrated before it is claimed.

Dataflow​

Dataflow declares best-effort stream processing at a stated level. It uses neither replicated authority nor replicated State.

Restart policy is separate​

A restart policy answers what happens after a process restart, reboot, or site-wide power loss.

That is different from deciding whether authority and data are replicated. The two settings must remain separate.

Orthogonal concerns​

A recovery model does not replace:

  • capability tags, which decide where a Cell may run,
  • execution shape, such as continuous stream processing,
  • Cell patterns, which describe the role a Cell plays in the Application.

When recovery models arrive, Myrmic will refuse a replicated stream deployment rather than silently degrade it.

Sovereign Cells​

A Sovereign Cell is a Cell that outlives the Node it runs on. A Consistent Cell becomes sovereign when it has both:

  • replicated authority from Partition Tolerance,
  • replicated committed data from Durability.

Partition Tolerance decides who may serve. Durability preserves what the Cell knows.

See also​

  • Roadmap - what future stages are intended to add
  • Guarantees - what the current release promises, and what it doesn't yet
  • Cell Patterns - recurring designs for combining Cells, Adapters, Agents, and Bridges
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