Deprecation Warnings

If your API has endpoints that are scheduled for deprecation, or are deprecated, Ketting can emit warnings in the console, so they are more likely spotted by a developer.

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:

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:

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 depreciation.

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

Deprecating links

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][3].

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

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

[3]: https://tools.ietf.org/html/draft-nottingham-link-hint-02 HTTP Link Hints