Google unveiled its plans what do you have about removing support for Server Push with Chrome 106, (which is scheduled for September 27) and that the change will also affect other browsers based on the Chromium code base.
For those of you who are new to Server Push technology, you should know that is defined in the HTTP/2 and HTTP/3 standards, and allows the server to send resources to the client without waiting for them to be explicitly requested.
It's supposed to be this way the server can speed up the page load, as the CSS files, scripts, and images needed to render the page will already be transferred to your side by the time the client requests it.
Analysis of HTTP/2 Server Push usage has mixed results ( Chrome , Akamai ), with no clear net performance gain and in many cases performance regressions.
Push was not implemented in many HTTP/3 servers and clients, although it was included in the . For much of the web using the newer HTTP/3 , Push has already been retired. Rerunning that analysis more recently, we see that the 1,25% HTTP/2 support by sites dropped to 0,7%.
As a reason for end of support unnecessary complication of implementation is mentioned of technology in the presence of simpler and no less effective alternatives, such as the label , from which the browser can request a resource without waiting for it to be used on the page. On the one hand, prefetch, compared to Server Push, generates an additional packet exchange (RTT), but on the other hand, it avoids sending resources that are already in the browser's cache. In general, the differences in delays when using Server Push and preloading are marked as negligible.
To initiate proactive loading on the server side, it is proposed to use the HTTP response code 103, which allows you to inform the client about the content of some HTTP headers immediately after the request, without waiting for the server to perform all operations. associated with the request and start serving the content.
103 Early Hints is a much less error-prone alternative with many of the same advantages as Push, and far fewer disadvantages. Instead of the server sending resources, 103 Early Hints sends only hints to the browser of resources that it can benefit from requesting them immediately. This leaves the browser in control of deciding whether or not it needs them, for example if it already has those resources in the HTTP cache.
Critical resource preloading is another alternative that allows the page and browser to work together to preemptively load critical resources early in the page load.
Similarly, it can provide hints about elements associated with the rendered page, which can be preloaded (for example, links to the CSS and JavaScript used in the page can be provided). Having received information about such resources, the browser can start downloading them without waiting for the end of the return of the main page, which reduces the total time of processing the request.
In addition to optimizing the load of resources, the Server Push mechanism could also be used to transmit data from the server to the client, but for these purposes, the W3C consortium develops the WebTransport protocol. The communication channel in WebTransport is organized over HTTP/3 using QUIC protocol as transport, WebTransport offers advanced features like multicasting, one-way broadcasting, out-of-order delivery, reliable and unreliable delivery modes.
According to Google statistics, Server Push technology has not received adequate distribution. Although Server Push is present in the HTTP/3 specification, in practice many client and server software products, including the Chrome browser, did not natively implement it. In 2021, about 1,25% of websites running on HTTP/2 used Server Push. This year, this figure has dropped to 0,7%.
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