An HTTP 200 Does Not Mean the Operation Succeeded

Mon, 01 Jan 2018 00:00:00 +0000

Two requests reach the same JSON application.

The first lacks authentication. The server returns HTTP 200 with this body:

{
 "status": 0,
 "error": {
 "code": 401,
 "message": "Unauthenticated"
 }
}

The second is authenticated but lacks permission to browse a collection. It also returns HTTP 200, this time with an empty array:

[]

Both behaviors are pinned by retained tests. Neither can be interpreted from the status code alone. Worse, the empty array is indistinguishable from an authorized search which genuinely found nothing.

A Timeout Is Part of the Contract

Fri, 01 Jul 2016 00:00:00 +0000

One remote accounting service would disappear for long periods and sometimes return with an expired TLS certificate. Another integration scheduled maintenance during peak operating hours. Work which normally completed quickly could occupy application capacity while the dependency was unable to help.

A timeout would not have made either provider reliable. It would have answered a question our callers still needed answered:

How long may this attempt wait before its result is no longer useful?

That answer belongs to the operation’s contract. Leaving it to a client library’s default lets a transport decide how much of the customer’s time and our worker capacity one dependency may consume.

Http on Brian Faust

An HTTP 200 Does Not Mean the Operation Succeeded

A Timeout Is Part of the Contract