WSP PDU Reference

Status: ACTIVE Date: 2026-03-04

Protocol reference for transport implementation and deterministic encoding/decoding.

Source grounding:

• spec-processing/source-material/WAP-230-WSP-20010705-a.pdf
• spec-processing/source-material/OMA-WAP-TS-WSP-V1_0-20020920-C.pdf

1) Service modes and directionality

• Connection-mode WSP is session oriented and relies on WTP.
• Connectionless WSP is request/reply over datagrams and relies on WDP.
• A configured profile must define active mode(s) and gate illegal operations.

2) Core PDU identifiers

• Connect (0x01)
• ConnectReply (0x02)
• Disconnect (0x05)
• Push (0x06)
• ConfirmedPush (0x07)
• Get method PDU region (0x40 – 0x4f)
• Post method PDU region (0x60 – 0x7f)
• DataFragment (0x80)

3) Abort and status code subset

• PROTOERR 0xE0 — protocol/state error
• DISCONNECT 0xE1 — session disconnected
• SUSPEND 0xE2 / RESUME 0xE3
• USERRFS / USERPND / USERDCR / USERDCU — push-specific outcomes

4) PDU shape

WspPdu {
  pdu_type,
  transaction_id,
  session_id,
  headers,
  content_type,
  body,
  protocol_options,
  capability_state,
}

Important: parsers are pure and should return structured types with all offset/remaining length available for layered validation.

5) Header and token model

• WSP uses tokenized headers/parameters with assigned-number tables (Tables 34/35/38/39 in OMA WSP 1.0).
• Header and content-type encoding should follow the specified uintvar and assignment strategies.
• Header code page 1 is the default page at the start of each header block.
• Header code page shifts use the explicit sequence 0x7F <page>.
• Default transport policy in this repo is strict: unknown tokens and unsupported extension pages reject deterministically.
• Optional header-lenient profile may ignore unsupported extension-page tokens and fall back to textual header encoding for extension headers.
• If the peer omits Encoding-version, assume binary support is 1.2 or lower.
• If a header requires a higher binary encoding version than the negotiated peer version, send it in text form.
• If a received binary header uses an unsupported encoding version or unsupported extension page, the deterministic transport status output is 400 with an Encoding-version response header describing supported versions; for unsupported extension pages, the response omits the version value for that page.

Required codec contract:

• decode_wsp_pdu(input: &[u8]) -> DecodeResult<WspPdu>
• encode_wsp_pdu(pdu: &WspPdu) -> Vec<u8>
• validate_wsp_pdu(pdu: &WspPdu) -> Result<(), ValidationError>
• encode_header(field, value) -> bytes
• decode_header(bytes) -> field/value
• validate_header(field, value) -> Result<(), Error>

Current transport-rust baseline for this lane:

• transport-rust/src/network/wsp/header_block.rs provides the immediate pure header-block decode/encode surface used to apply header token, code-page, and Encoding-version policy before full PDU framing is implemented.
• transport-rust/src/network/wsp/pdu.rs now provides a minimal pure PDU surface for Get, Post, and Reply over that header-block layer.
• transport-rust/src/network/wsp/session.rs classifies those PDUs into narrow WSP method request/result events with explicit connectionless vs connection-oriented mode tags for replay scaffolding.
• transport-rust/tests/fixtures/transport/wsp_pdu_baseline_mapped/pdu_fixture.json carries the replayable baseline corpus for successful Get/Post/Reply framing and deterministic decode failures.
• transport-rust/tests/fixtures/transport/wsp_session_method_baseline_mapped/session_fixture.json carries replayable session-method classification cases that T0-22 can promote into interop replay fixtures.

6) Connection-mode behavior (typical)

1. S-Connect.request
2. S-Connect.indication/reply
3. Method Get/Post request
4. Method reply
5. S-Disconnect on shutdown

On disconnect:

• abort pending transactions,
• invalidate pending confirmations,
• prevent further stateful operations until reconnect or profile reset.

7) Connectionless behavior (typical)

1. method GET/POST request
2. optional server request body (Reply)
3. no stateful transaction service primitives at WSP service interface
4. no connect/disconnect service states

8) Session/service primitives from spec matrix

• Capability negotiation is performed during session setup.
• Session headers and protocol headers carry through to service users.
• Push is unsolicited from peer and can be non-confirmed or confirmed based on feature bits.

9) Immediate parser/output contract for this codebase

Use this shape for transport-facing decode/encode tests:

pub enum WspPdu {
    Connect(WspConnectPdu),
    ConnectReply(WspConnectReplyPdu),
    Disconnect(WspDisconnectPdu),
    MethodGet(WspMethodGetPdu),
    MethodPost(WspMethodPostPdu),
    Reply(WspReplyPdu),
    Push(WspPushPdu),
    ConfirmedPush(WspPushPdu),
    DataFragment(WspDataFragmentPdu),
}

10) Deferred (spec-accurate completion)

• complete confirmed-push timing and delayed-ack policy,
• full appendix-C race-condition handling for incomplete state transitions.