Editing Web server (section)

=== New challenges (2015 and later years) ===
In 2015, RFCs published new protocol version [HTTP/2], and as the implementation of new specifications was not trivial at all, a '''dilemma arose among developers of less popular web servers''' (e.g. with a percentage of usage lower than 1% .. 2%), about adding or not adding support for that new protocol version.<ref name="http2-faq-http2-replace-http1">{{Cite web|url=https://http2.github.io/faq/#will-http2-replace-http1x|title=Will HTTP/2 replace HTTP/1.x?|author=|publisher=IETF HTTP Working Group|access-date=2021-12-22|archive-date=27 September 2014|archive-url=https://web.archive.org/web/20140927004541/http://http2.github.io/faq/#will-http2-replace-http1x|url-status=live}}</ref><ref name="ws-http2-support">{{Cite web|url=https://github.com/httpwg/http2-spec/wiki/Implementations|title=Implementations of HTTP/2 in client and server software|author=|publisher=IETF HTTP Working Group|access-date=2021-12-22|archive-date=23 December 2021|archive-url=https://web.archive.org/web/20211223003728/https://github.com/httpwg/http2-spec/wiki/Implementations|url-status=live}}</ref>

In fact supporting HTTP/2 often required radical changes to their internal implementation due to many factors (practically always required encrypted connections, capability to distinguish between HTTP/1.x and HTTP/2 connections on the same TCP port, binary representation of HTTP messages, message priority, compression of HTTP headers, use of streams also known as TCP/IP sub-connections and related flow-control, etc.) and so a few developers of those web servers opted for [[Comparison of web server software#Features|not supporting new HTTP/2 version]] (at least in the near future) also because of these main reasons:<ref name="http2-faq-http2-replace-http1" /><ref name="ws-http2-support" />
* protocols HTTP/1.x would have been supported anyway by browsers for a very long time (maybe forever) so that there would be no incompatibility between clients and servers in next future;
* implementing HTTP/2 was considered a task of [[HTTP/2#Criticisms|overwhelming complexity]] that could open the door to a whole new class of [[Software bug|bug]]s that till 2015 did not exist and so it would have required notable investments in developing and testing the implementation of the new protocol;
* adding HTTP/2 support could always be done in future in case the efforts would be justified.

Instead, developers of '''most popular web servers, rushed to offer the availability of new protocol''', not only because they had the work force and the time to do so, but also because usually their previous implementation of [[SPDY]] protocol could be reused as a starting point and because most used web browsers implemented it very quickly for the same reason.  Another reason that prompted those developers to act quickly was that webmasters felt the pressure of the ever increasing [[web traffic]] and they really wanted to install and to try – as soon as possible – something that could drastically lower the number of TCP/IP connections and speedup accesses to hosted websites.<ref name="http2-faq-just-1-connection">{{Cite web|url=https://http2.github.io/faq/#why-just-one-tcp-connection|title=Why just one TCP connection?|author=|publisher=IETF HTTP Working Group|access-date=2021-12-22|archive-date=27 September 2014|archive-url=https://web.archive.org/web/20140927004541/http://http2.github.io/faq/#why-just-one-tcp-connection|url-status=live}}</ref>

In 2020–2021 the HTTP/2 dynamics about its implementation (by top web servers and popular web browsers) were partly replicated after the publication of advanced drafts of future RFC about [[HTTP/3]] protocol.