HTTP headers vs payload

[cportele]

One design question is whether information about a resource returned by the server should be put in the HTTP headers or included in the payload.

Advantages of using HTTP headers:

• If well-known headers exist like "Date" (for the timestamp) or "Link" (for qualified links), using those generic Web mechanisms would seem clearer than defining OGC/API-specific payload.
• If existing payloads cannot be extended with additional information (e.g. a GML-SF0 feature collection or a PNG), using headers enables the direct reuse of such payloads, too.

Disadvantages of using HTTP headers:

• For responses that will benefit from "streaming" (i.e., starting the response before the complete response is known), e.g. a query response, some information may not be available when the headers are written. numberMatched or some resource links are examples.
• If only the payload is saved, the information in the header is "lost". It is unclear, if this is really an issue.

[cportele]

Discussion in meeting 2017-11-28: Include links in the payload, but add recommendation to include links also in the header if there are not too many and the links are known, when the response is started.