Google warned about the disconnection of Server Push technology in the release of Chrome 106, outlined on September 27. Other browsers based on the code base Chromium will also affect the changes. Technology Server Push defined in the standards http/2 and http/3, and allows the server to send resources to the client, not Waiting for their obvious request. It is assumed that in this way the server can speed up the loading of the page, since the CSS files necessary for the page drawing, scripts and images by the time of request by the client will be transferred to his side.
The reason for the termination of support mentions excessive complication of the implementation of the technology in the presence of simpler and no less effective alternatives, such as a tag, on the basis of which a browser can request a resource without waiting for its use on the page. On the one hand, Preload compared to Server Push leads to excess package exchange (RTT), but on the other hand, it allows you to avoid sending resources that are already available in the browser cache. In general, the differences in delays using Server Push and Preload are noted as insignificant.
To initiate a proactive load on the server side, it is proposed to use the HTTP answer code 103 , which allows you to inform the client about the content of some HTTP-heads immediately after the request, without waiting for the server, it fulfills all the operations related to the request and begins the return of the content. Similarly, you can report hints about the elements related to the page given, which can be pre -loaded (for example, links to the CSS and JavaScript page can be given. Having received information about such resources, the browser can start loading them without waiting for the end of the return of the main page, which allows you to reduce the total time processing time.
In addition to optimizing resources loading, the SERVER PUSH mechanism could also be used for streaming data from the server to the client, but for these purposes, the W3C consortium develops the protocol webtransport . The communication channel in Webtransport is organized on top of HTTP/3 using the QUIC protocol as transport. Webtransport offers such advanced opportunities as the organization of transmission to several flows, unidirectional flows, delivery without taking into account the procedure for sending packages (out-off-Order), reliable and unreliable delivery modes.
According to Google statistics, Server Push technology has not received proper distribution. Despite the fact that Server Push is present in the specification http/3, in practice Many server and client software products, including Chrome browser, did not initially sell it. In 2021 about 1.25% of sites operating on http/2, used Server Push. This year this indicator decreased to 0.7%.