StreamLD Subscription and Discovery

Draft Community Group Report,

This version:
https://openfaster.org/streamld/subscription
Issue Tracking:
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Editor:
OpenFASTER Editors

Abstract

Defines how a client discovers a stream’s subscription endpoint(s), independent of which transport binding (StreamLD SSE Binding or StreamLD WebSocket Replication Binding) it then uses. Part of the StreamLD module.

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1. Overview

This document separates *discovering* a stream’s subscribable endpoint from *subscribing* to it over a specific transport — the same separation StreamLD SSE Binding and StreamLD WebSocket Replication Binding rely on, and the same one AsyncAPI draws between its Channel and Operation objects.

2. Discovery

A StreamLD resource MUST advertise its subscription endpoint(s) via one `Link` response header per supported transport binding, using a `rel` value scoped to that binding (e.g. `rel="https://openfaster.org/streamld#sse"` or `rel="https://openfaster.org/streamld#websocket-replication"`). A client MUST NOT assume a fixed URL pattern (such as appending `/subscribe`) — the `Link` header is the only conformant discovery mechanism.

Conformance

Document conventions

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example", like this:

This is an example of an informative example.

Informative notes begin with the word “Note” and are set apart from the normative text with class="note", like this:

Note, this is an informative note.

References

Normative References

[RFC2119]
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: https://datatracker.ietf.org/doc/html/rfc2119