Lingue Protocol (Draft)

Scope and Transport

Default environment: XMPP with MUC for human-visible messages and private chat stanzas for structured exchange.
No custom XMPP extension required initially; rely on XEP-0030 (disco#info) for capability discovery and XEP-0045 for rooms. Payloads may carry RDF/Turtle, Prolog, or plain text in <body> or Lingue payload elements.

Roles

Lingue Agent: advertises capabilities, negotiates, executes ASK/TELL.
Human: participates via lng:HumanChat; may trigger negotiations.

Capability Advertisement

Use disco#info features with Lingue IRIs, e.g.:
- http://purl.org/stuff/lingue/feature/lang/human-chat
- http://purl.org/stuff/lingue/feature/lang/ibis-text
- http://purl.org/stuff/lingue/feature/lang/prolog
- http://purl.org/stuff/lingue/feature/lang/agent-profile-exchange
- http://purl.org/stuff/lingue/feature/channel/xmpp-muc

Minimal Negotiation Flow

Discover — request disco#info; inspect shared features.
Offer — post to room: “Lingue-capable; supports IBIS and Prolog; reply ‘yes ibis’ to enable structured exchange.”
Accept — peer responds privately (NL or form) selecting a feature/lang/*.
Exchange — switch to agreed mode; structured payload + short human summary posted to room (meta-transparency).
Close — send summary to room; optionally provide link/IRI for persisted artifacts.

Payload Conventions

Agent profile exchange: Turtle/XML carrying lng:Profile and dependencies; include a one-line purpose.
Human-like chat: free text in <body>.
IBIS-augmented text: plain text plus optional RDF snippet (Turtle) in a payload; always include one-line IBIS summary in the room.
Prolog: text/x-prolog clauses in a payload; include intent (“query for issue-12 positions”) and expected bindings.
Status/meta-transparency: payload in lng:HumanChat mode with JSON { type: "status", ... } and empty <body> when suppressing chat noise.

ASK/TELL Semantics

ASK: request graph pattern or capability; in RDF, use lng:asks linking agent to an lng:Exchange that contains the graph pattern. Include a paraphrase in <body>.
TELL: assert graph; use lng:tells; include provenance (who/when) and mode (lng:IBISText or lng:PrologProgram). Always pair with a plain-language summary to the room when exchanged privately.

Example Stanzas

Discovery result

<iq type="result" from="agent@example.org">
  <query xmlns="http://jabber.org/protocol/disco#info">
    <feature var="http://purl.org/stuff/lingue/feature/lang/human-chat"/>
    <feature var="http://purl.org/stuff/lingue/feature/lang/ibis-text"/>
    <feature var="http://purl.org/stuff/lingue/feature/lang/prolog"/>
    <feature var="http://purl.org/stuff/lingue/feature/lang/agent-profile-exchange"/>
    <feature var="http://purl.org/stuff/lingue/feature/channel/xmpp-muc"/>
  </query>
</iq>

Offer structured exchange (private)

<message to="peer@example.org" type="chat">
  <body>I can share IBIS RDF or Prolog queries. Choose a mode?</body>
  <x xmlns="jabber:x:data" type="form">
    <field var="mode" type="list-single">
      <option label="IBIS Text"><value>http://purl.org/stuff/lingue/feature/lang/ibis-text</value></option>
      <option label="Prolog"><value>http://purl.org/stuff/lingue/feature/lang/prolog</value></option>
    </field>
  </x>
</message>

TELL (IBIS snippet + NL summary)

<message to="peer@example.org" type="chat">
  <body>Summary: Position = migrate to CoAP; supports: lower overhead, IoT fit.</body>
  <payload xmlns="http://purl.org/stuff/lingue/" mime="text/turtle" mode="http://purl.org/stuff/lingue/IBISText"><![CDATA[
@prefix ibis: <https://vocab.methodandstructure.com/ibis#> .
@prefix lng:  <http://purl.org/stuff/lingue/> .

:pos-001 a ibis:Position ;
  ibis:responds-to :issue-12 ;
  rdfs:label "Migrate to CoAP" .
  ]]></payload>
</message>

Status payload (room transparency)

<message to="room@conference.example.org" type="groupchat">
  <body></body>
  <payload xmlns="http://purl.org/stuff/lingue/" mime="application/json" mode="http://purl.org/stuff/lingue/HumanChat">
    {"type":"status","sessionId":"abc-123","message":"MFR solution request for abc-123","timestamp":"2025-12-28T09:20:21.448Z"}
  </payload>
</message>

Error and Fallback

If no shared features are discovered, remain in lng:HumanChat and state that structured exchange is unavailable.
On timeouts or rejections, announce to the room: e.g., “Structured exchange declined; continuing in plain chat.”

Security and Integrity (initial)

Do not transmit secrets; Prolog payloads MUST be sandboxed by receivers.
Agents SHOULD sign or provide retrievable IRIs for profile documents; consumers validate before execution.

Open Items for Review

Confirm IRIs for protocol states (e.g., negotiation open/closed).
Add SHACL for MUC initiation policy and feature intersection validation.
Decide where IBIS/Prolog artifacts are persisted (room log vs. external store).

Change Notes

0.1.1: clarified payload elements (mode/mime metadata) and status JSON for meta-transparency.