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Domain Bridge#

The domain bridge connects Agnocast publishers and subscribers that run under different ROS_DOMAIN_IDs on the same machine — with zero copy. You register a rule for a topic, and Agnocast delivers that topic across the two domains by sharing the publisher's shared-memory message directly: no serialization, no relay process.

This is not the Agnocast–ROS 2 Bridge

The Bridge connects Agnocast nodes to standard ROS 2 (RMW) nodes. The domain bridge on this page connects Agnocast nodes in one ROS_DOMAIN_ID to Agnocast nodes in another. They are independent features that happen to share the word "bridge".

Domain isolation#

Agnocast honors ROS_DOMAIN_ID: a publisher and a subscriber connect only when they share the same domain, matching ROS 2 semantics. (Earlier versions ignored the domain — every Agnocast endpoint in an IPC namespace connected to every other one.)

The domain bridge is the opt-in exception to that isolation. It re-connects specific topics across one specific pair of domains, and nothing else.

Scope#

  • Zero copy, same IPC namespace only. The bridge shares the publisher's memory directly, so both domains must be on the same machine and in the same IPC namespace. Crossing ECUs or IPC namespaces is not covered here — that goes through the Agnocast–ROS 2 Bridge over DDS, with a copy. See Limitations.
  • Agnocast ↔ Agnocast only, in performance mode.

Next steps#

  • Configuration — write a rule file and register it with register_domain_bridge before your nodes start.
  • Constraints & differences — how the Agnocast domain bridge differs from the ROS 2 domain_bridge.