xml-pipeline/docs/message-pump.md

Message Pump — End-to-End Flow (v2.0)

The AgentServer message pump processes individual messages through a single, linear, attack-resistant pipeline. The outer dispatcher runs a continuous async loop, draining per-thread message buffers (queues) until empty — enabling persistent, branched reasoning without artificial limits.

flowchart TD
    subgraph MessagePump
    subgraph Init
    start([Start])
    raw[/Optional<br>Raw Bytes/]
    wrapstart["Wrap<br>&ltstart&gt{...}&lt/start&gt"]
    end
    enq1([QUEUE 1])
    rawwaiting{Raw<br>Msg<br>Waiting?}
    waitRaw([Wait])
    subgraph Process
    extract["Extract<br>Tree"]
    split["Split<br>Tree"]
    subgraph foreach [For Each Message]
        getmsg[Get Msg]
        badTo{&ltTo&gt Missing?}
        endnoto([Discard])
        addfrom["Add .from"]
        repair[Repair + C14N]
        validate[Validate]
        invalidMsg{Bad<br>Message?}
        badmsg([Discard])
        more{More?}
    end
    enqueue([QUEUE 2])
    xmlWaiting{XML<br>Waiting?}
    waitXml([Wait])
    subgraph Async
    lookup[Lookup Listener] 
    route[Route]
    wait[await Response]
    wrap["Wrap<br>&ltfrom&gt{...}&lt/from&gt"]
    end
    end
    end
    
    start --> raw --> wrapstart --> enq1 --> rawwaiting 
    rawwaiting --> |NO| waitRaw
    rawwaiting ---> |YES| extract
    extract --> split --> foreach
    getmsg --> badTo
    badTo --> |YES| endnoto
    badTo --> |NO| addfrom --> repair --> validate --> invalidMsg
    invalidMsg ---> |NO| more --> |Yes| getmsg
    invalidMsg --> |YES| badmsg
    more --> |NO| enqueue
    enqueue --> xmlWaiting
    xmlWaiting --> |NO| waitXml
    xmlWaiting ---> |YES| lookup --> route --> wait --> wrap --> enq1
    

Detailed Stages (Per-Message)

1. Ingress/Enqueue: Raw bytes → repair → preliminary tree → enqueue to target thread buffer.

2. Dispatcher Loop: Single async non-blocking loop selects next message from per-thread queues (breadth-first default for fairness).

3. Processing:

   • Full repair + C14N.

   • Envelope validation.

   • Routing decision:

     • Meta Branch (https://xml-pipeline.org/ns/meta/v1 namespace): Handled directly by privileged core handler (no listener lookup or XSD validation needed).
       • Purpose: Introspection and reserved organism primitives.
       • Examples:
         • request-schema, request-example, request-prompt, list-capabilities (returns XSD bytes, example XML, prompt fragment, or capability list).
         • Thread primitives like spawn-thread, clear-context.
       • Privileged: Controlled via YAML meta flags (e.g., allow_schema_requests: "admin" or "none"). Remote queries optional.
       • Why separate: Faster, safer (no user listener involved), topology privacy preserved.
     • Capability namespace → normal listener route (XSD validation + deserialization).

   • Typed handler call → raw bytes.

4. Response Handling:

   • Dummy wrap → extract multi-payloads.
   • Each enqueued as new message(s) in appropriate thread buffer(s).

5. Egress: Dequeue → C14N/sign → send.

Key Properties

• Continuous looping until all thread buffers empty — natural iteration/subthreading without one-shot constraints.
• Multi-payload enqueues enable parallel branches/thoughts.
• Scheduling balances deep dives vs fair exploration.
• Attack-resistant at every step.

XML in → queued → processed → multi-out → re-queued. Loops forever if needed. Safely. Permanently.