POST requests can be cached?

[ghost]

Re: https://rubenverborgh.github.io/WebFundamentals/web-apis/#soap-generation

Surprisingly, it seems that using POST does not necessarily imply non-cacheability.

From the spec:

Responses to this method are not cacheable, unless the response includes appropriate Cache-Control or Expires header fields.

What do you make of this?

[RubenVerborgh]

It's not just POST, but the way it is used: SOAP endpoints are exposed through a single URL, and the equivalent of resource identification happens through request bodies. In other words, whether the client requests “book 35“ or “song 47”, the requests will not differ in URL but only in request body. And HTTP caching happens by request URL and headers.

So the only way a SOAP response can be cached correctly using HTTP is in the pathological case where the endpoint offers a single response for all of its operations (including errors). In other words: not gonna happen.