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No, this is simply not true. If you change "example-1.2.3.js" to "example-1.2.4.js" in the response to `/{resource}/{id}`, it does not change the underlying res

by Timon3 2y ago

No, this is simply not true. If you change "example-1.2.3.js" to "example-1.2.4.js" in the response to `/{resource}/{id}`, it does not change the underlying resource. The included script is simply a part of the representation of the resource, but it's not the resource itself. The representation of the resource can change without the resource itself changing. https://httpwg.org/specs/rfc9110.html#rfc.section.3.2 https://httpwg.org/specs/rfc9110.html#rfc.section.3.2 You can change "index.html" as much as you want to, as long as the resource it represents stays the same. "index.html" is not a resource, it's a representation of a resource. If you still disagree, please explain how "index.html" and "index.json" can be representations of the same resource.

kbolino 2y ago
They are not the same resource. Every resource is uniquely identified by its URI (normalized, ignoring the fragment), and so https://example.com/index.html https://example.com/index.html and https://example.com/index.json https://example.com/index.json are therefore not the same resource. Perhaps what you are thinking of is content negotiation. I can request https://example.com/index.html https://example.com/index.html and (despite the name) get JSON back, either because the server is cheeky or because I said "Accept: application/json" or similarly expressed a preference for JSON over HTML. Assuming both JSON and HTML exist at the same URI, these would be two representations of the same resource (accessed from the same URI, but with different headers). Broadly speaking, however, this mechanism is not often used outside of certain specialized protocols, and so it generally doesn't matter: changing the HTML bytes of index.html changes the resource because HTML is the only representation. Per the contract that specifies method idempotence and safety, GET index.html should therefore never cause the HTML content I receive back to change. However, the HTML content can change between requests for other reasons. Whether changing only one representation of a resource is the same as changing the "whole" resource somehow is a bit moot, because the specific representation is what's consumed by the client and stored by caches. The ETag and cache parameters are tied to the specific representation as well, and can't be "smeared" across all representations. Practically speaking, the resource is inseparable from its representation, and thus two different representations are treated by well behaved HTTP clients and caches the same as two different resources, even if a higher-level protocol (SOAP, WebDAV, etc.) might treat them as semantically equivalent. This is my read of RFCs 9110 and 9111; if you have strong evidence otherwise, I'm open to it.

by Timon3 2y ago

kbolino 2y ago

They are not the same resource. Every resource is uniquely identified by its URI (normalized, ignoring the fragment), and so https://example.com/index.html https://example.com/index.html and https://example.com/index.json https://example.com/index.json are therefore not the same resource. Perhaps what you are thinking of is content negotiation. I can request https://example.com/index.html https://example.com/index.html and (despite the name) get JSON back, either because the server is cheeky or because I said "Accept: application/json" or similarly expressed a preference for JSON over HTML. Assuming both JSON and HTML exist at the same URI, these would be two representations of the same resource (accessed from the same URI, but with different headers). Broadly speaking, however, this mechanism is not often used outside of certain specialized protocols, and so it generally doesn't matter: changing the HTML bytes of index.html changes the resource because HTML is the only representation. Per the contract that specifies method idempotence and safety, GET index.html should therefore never cause the HTML content I receive back to change. However, the HTML content can change between requests for other reasons. Whether changing only one representation of a resource is the same as changing the "whole" resource somehow is a bit moot, because the specific representation is what's consumed by the client and stored by caches. The ETag and cache parameters are tied to the specific representation as well, and can't be "smeared" across all representations. Practically speaking, the resource is inseparable from its representation, and thus two different representations are treated by well behaved HTTP clients and caches the same as two different resources, even if a higher-level protocol (SOAP, WebDAV, etc.) might treat them as semantically equivalent. This is my read of RFCs 9110 and 9111; if you have strong evidence otherwise, I'm open to it.