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0 points_alphageek4d ago0 comments

>> QUERY request can be cached

I have a weird feeling. Query body is encrypted by https. So CDN will not be able to cache results. In order to make it work right - whole topology of the internet should be redone. Caching on the backend server will not give any real gains for large scale apps.

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6 comments · 1 top-level

CodesInChaos4d ago· 5 in thread

The whole connection is encrypted by https, the request body is treated the same as the url, the headers or the response. The only unencrypted parts are the IP addresses/ports and the domain name (if SNI without ECH is used).

CDNs already terminate TLS connections so they can cache GET requests.

rileymat24d ago

I think a lot of people don’t know the http/1.x protocol from url (header) to body is a stream of text* separated by \r\n.

* the body may be compressed.

vshulcz4d ago

Even past the TLS point (CDNs terminate TLS, so they can read the body) there's a harder problem nobody's solved: to cache a QUERY the cache has to fold the body into the cache key, and there's no standard way to canonicalize a request body. {"a":1,"b":2} and {"b":2,"a":1} are the same query and two different cache entries; whitespace, float formatting, unordered keys all fork the key. GET gets this for free because the URL is already a normalized string. So "cacheable in principle" is real, but "actually cached" needs every layer to agree on a canonical form first - the same coordination problem that killed GET-with-body. I want QUERY for the honest semantics; I just wouldn't budget for cache hits yet

lightningspirit4d ago

> {"a":1,"b":2} and {"b":2,"a":1} are the same query and two different cache entries

These two payloads are actually different. You're talking about semantics, which is determined by the payload format; in the case of JSON, these two are semantically similar.

> GET gets this for free because the URL is already a normalized string

It's the same principle; the order of properties matters too.

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CodesInChaos4d ago

I think the simple approach of using a bitwise comparison will result in satisfactory caching for most applications.

Yokohiii4d ago

Can you elaborate? Do you think the noted issues are non-issues that should be fixed in applications? Which would require a new standard to create stable JSON outputs, which is just one use case that can fail right now.

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