docs: modernize HTTP/2 ALPN and h2c guidance - #1253
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samueleresca merged 2 commits intoSep 6, 2026
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Motivation: The HTTP/2 server-side doc still described ALPN as requiring separate negotiation setup and documented a JDK <= 9 fallback where curl could not determine h2 support, plus it presented the HTTP/1.1 h2c Upgrade mechanism without noting it is now obsolete per RFC 9113. Apache Pekko HTTP's minimum supported JDK has since moved to 17, where ALPN is natively part of JSSE and the RFC 7540 Upgrade path has been superseded. Modification: Reword the ALPN section to state it needs no extra provider or boot classpath configuration on supported JDKs, and link to RFC 7301/RFC 9113 instead of RFC 7540. Add a warning that h2c Upgrade is obsolete in RFC 9113 and should only be used for older-client compatibility, rename the "h2c with prior knowledge" section to "Cleartext HTTP/2 with prior knowledge", and drop the outdated JDK <= 9 curl fallback example that no longer applies on the project's supported JDKs. Result: The doc reflects the project's current JDK baseline and RFC 9113 guidance without the stale JDK <= 9 ALPN caveat or unlabeled deprecated h2c Upgrade mechanism. Tests: Not run - docs only References: None - documentation accuracy update
pjfanning
reviewed
Aug 30, 2026
pjfanning
reviewed
Aug 30, 2026
pjfanning
reviewed
Aug 30, 2026
pjfanning
reviewed
Aug 30, 2026
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@samueleresca would you time to have a look at my review comments? The changes themselves are useful. |
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Taking a look at it later |
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@pjfanning This should now be updated. |
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Motivation:
The HTTP/2 server-side doc still described ALPN as requiring separate negotiation setup and documented a JDK <= 9 fallback where curl could not determine h2 support, plus it presented the HTTP/1.1 h2c Upgrade mechanism without noting it is now obsolete per RFC 9113. Apache Pekko HTTP's minimum supported JDK has since moved to 17, where ALPN is natively part of JSSE and the RFC 7540 Upgrade path has been superseded.
Modification:
Reword the ALPN section to state it needs no extra provider or boot classpath configuration on supported JDKs, and link to RFC 7301/RFC 9113 instead of RFC 7540. Add a warning that h2c Upgrade is obsolete in RFC 9113 and should only be used for older-client compatibility, rename the "h2c with prior knowledge" section to "Cleartext HTTP/2 with prior knowledge", and drop the outdated JDK <= 9 curl fallback example that no longer applies on the project's supported JDKs.
Result:
The doc reflects the project's current JDK baseline and RFC 9113 guidance without the stale JDK <= 9 ALPN caveat or unlabeled deprecated h2c Upgrade mechanism.
Tests:
Not run - docs only
References:
None - documentation accuracy update