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Ketting support for deprecation warnings

syndicated from on February 1, 2021

Ketting is the generic REST client for Javascript.

Version 7 is currently in beta, and will have support for Deprecation and Sunset headers as well as deprecated links.

Deprecating Endpoints/Resources

There’s currently work done on a new internet standard: draft-cedik-deprecation-header, a.k.a.: “The Deprecation HTTP Header Field”.

The way this works is that the server may emit a header such as one of these:

HTTP/1.1 200 OK
Deprecation: Mon, 1 Nov 2021 00:00:00 GMT
Deprecation: true

If a server emits these, it tells the client that the endpoint should no longer be used, or will be removed at a future date.

If specified, Ketting will now send warnings to the console via console.warn, making it easier to spot reliance on deprecated endpoints.

The draft also defines the following additional headers:

HTTP/1.1 200 OK
Sunset: Wed, 1 Dec 2021 00:00:00 GMT
Link: </docs/update-2021>; rel="deprecation"

These headers allow a server to tell a client when the endpoint will stop responding, and point to additional information about the deprecation.

If either of these are specified, Ketting will provide this information in the console.

Aside from entire resources being deprecated, individual links may also get deprecated. Given a HAL document, this may look like the following:

  "_links": {
    "next": {
      "href": "/next-page",
      "hints": {
        "status": "deprecated"

The format for ‘hints’ is documented in draft-nottingham-link-hint.

When you follow the next link with Ketting, Ketting will now also emit a console warning.

// Emits warning
const nextResource = await resource.follow('next')

Want to give this a shot? Update to the latest Ketting with:

npm i ketting@beta