RFR: 8355572: Support HTTP Range requests in Simple Web Server [v2]

[Daniel Fuchs]

On Wed, 29 Oct 2025 10:54:58 GMT, Peyang <duke at openjdk.org> wrote:

>> In addition should the Etag be considered weak as there is no way to guarantee that the file won't be modified between the time the attributes are read and the time the file content is read?
>
> Thank you for your reviews.
> I initially added `ETag` header for `If-Range` because I misunderstood it was a requirement, but it is actually not mandatory. So I will remove it from this patch.
> If a follow-up ticket could be created, since I don’t have permissions, I’d be happy to take it on.
> However, whether supporting ETag here is truly necessary is still open for discussion.

Do we also need/want to support `If-Range`? The thing is that we can't guarantee that the file will not be modified (either externally or by other threads in the same VM) after having read the last modified date. How strong is the guarantee provided by `If-Range` supposed to be?

[RFC 9110](https://www.rfc-editor.org/rfc/rfc9110.html#name-last-modified) seems to imply that `Last-Modified` only provides a weak guarantee - as it is documented as "the date and time at which the origin server believes the selected representation was last modified". 

Does the same apply for `If-Range`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/28021#discussion_r2474374557