Interaction Bindings

An interaction binding relates the semantic and structural parts of an interaction at one exact boundary without making them identical. It states how interface contract roles and protocol roles attach through endpoints to exact channel directions, and which realization is authorized to carry them.

Bindings are the reconciliation layer among interface, protocol, channel, endpoint, and realization. An interface can have several bindings; one channel can carry several distinguishable interface roles; one protocol can span several channels; and a new binding can preserve an interface contract while changing transport, topology, or endpoint placement.

Binding Contents

A complete binding may identify:

the boundary, participants, and provided or required interface roles;
exact operation, event, request, reply, stream-item, or other carried contracts;
protocol roles, initiation rules, correlation, and terminal outcomes;
exact channel definition revision and channel directions;
the ports and logical endpoints attached to each direction;
envelope interpretation, framing, codec, and compatibility rules;
routing, addressing, subscription, or response-target rules;
required operational properties at each boundary; and
the attributable realization plan, adapter, and capability evidence.

A binding should reference canonical contracts and channel directions rather than copying them. This preserves identity and evolution independently: revising an endpoint address need not revise a semantic request contract, and revising a contract does not silently retarget an existing channel.

Request and Reply

A request/reply binding maps one request contract and its terminal reply contracts to two independently identified directions. The binding records whether the directions belong to one coupled exchange or to paired one-way channels.

request contract --bound to--> request direction
reply contract   --bound to--> reply direction

The reply direction may be physically coupled to the invocation, selected through an explicit response target, correlated through a shared topic or stream, or observed through another channel. Those choices do not change which reply discharges which request. Correlation, response obligation, timeout, cancellation, and winner rules remain protocol and contract concerns.

Logical and Physical Binding

A logical binding relates contracts, roles, directions, and endpoints in the system graph. A realization binding supplies concrete provider or protocol artifacts such as routes, addresses, topics, subscriptions, stream identifiers, codecs, credentials, and client configuration.

The realization binding must be validated against the exact logical definition and capability context. A stale plan, compatible-looking provider name, or raw transport handle is not sufficient authority. Derived artifacts can change while the logical binding remains stable, but a changed realization must still preserve every demanded property at its declared boundary.

Bindings can be layered. A message publication binding may lower into a broker client protocol binding, which lowers into one or more network-channel bindings. Each layer introduces its own endpoints, identifiers, acknowledgments, failure cuts, and control exchanges. The composed realization must state which upper-layer structure each lower-layer binding preserves and which details it introduces or forgets.

Distinctions

Term	Distinction from a binding
interface	Defines available semantic roles and obligations; a binding attaches those roles to structure.
interaction protocol	Defines legal traces; a binding assigns protocol roles to exact endpoints and directions.
channel	Defines the logical exchange and scoped demands; a binding states what the channel carries for this interaction.
endpoint	Is one attachment locus; a binding relates the loci on all participating sides.
port	Is a component's named provided or required interface role; a binding connects that role to a channel endpoint.
adapter	Translates between bound roles and concrete mechanisms; it is part of realization rather than the binding's semantic authority.
address	Names or selects a path, channel, or endpoint; changing an address need not change the logical binding.

Formal relations

arranges: Interfaces — An interaction binding attaches provided and required interface roles to exact channel directions and endpoints.
arranges: Interaction Protocols — An interaction binding assigns protocol roles to participants and channel directions without redefining their legal traces.