XPression Bridge Protocol and Payload Reference

Choose among WebSocket DataLinq, captioning TCP server/client, RSS over HTTP, and UDP with simple-text, JSON, or XML payloads.

Best for: XPression operators, graphics engineers, caption operators, broadcast engineers, production IT, and licensed desktop administrators.

Before you start

Requires an active 4All organization/event, authorized desktop account, eligible XPression Bridge license, supported app build, and a network path to 4All plus the selected XPression protocol.

• Document the 4All event/language and XPression scene/DataLinq design.
• Know the bridge/XPression machines, IP interfaces, protocol, direction, port, firewall owner, and final program return.
• Prepare a backup output and an off-air test scene.

Reference

1. WebSocket DataLinq. Use when XPression/DataLinq or a compatible client connects to a WebSocket endpoint and benefits from continuous structured state.
2. Captioning TCP. Choose server or client mode according to connection ownership and caption ingest design.
3. RSS HTTP. Expose a polled HTTP feed where DataLinq expects RSS/XML-style retrieval.
4. UDP. Use low-overhead datagrams only on a trusted engineered network; delivery is not guaranteed.
5. Simple text. Best for a single text field or simple parser.
6. JSON. Use for caption, lines, speaker, language, sequence, time/latency, and structured mapping.
7. XML. Use when XPression/DataLinq mapping expects XML fields.
8. Test parser compatibility. Inspect payload preview and special characters.
9. Document network contract. Direction, host, port, format, refresh/reconnect.

Use this reference to confirm: The Bridge transports the correct 4All caption state to the intended XPression scene with verified formatting, timing, monitoring, and recovery.

Validation checks

• The chosen client receives parseable payloads and mapped fields update correctly after reconnect.

Compatibility notes

Connected but no fields

Payload format/path does not match parser/mapping.

UDP loss

Use engineered LAN or a connection-oriented protocol.

TCP direction wrong

Correct server/client ownership and firewall.

Limits and cautions

• Restrict bind interfaces/ports.
• Do not transmit sensitive captions over untrusted networks without approved protection.
• Exact payload schema should be versioned with graphics templates.

Related guides

• Install and Update 4All XPression Bridge
• XPression Bridge Protocol and Payload Reference
• Collect XPression Bridge Logs and Diagnostics

Documentation status: Draft based on XPression Bridge repository version 0.1.59. Validate the installed release, supported OS, license policy, and live graphics workflow before publishing.