ArcGIS Enterprise support for HTTP/2

[BillMitchell]

HTTP/2 provides performance and parallelization improvements over HTTP/1.1, notably solving the head-of-line blocking problem.  This is particularly important when loading minified javascript modules, such as the web map viewer.

Although HTTP/2 effectively requires TLS, the default Enterprise setup uses TLS on ports 7443 and 6443 so this requirement isn't above what is already a default (and good practice).

Apache Tomcat has supported HTTP/2 since version 8.5; version 9 was included with ArcGIS Server 11.2, so this should be stable and may be as simple as a configuration change.  From my testing by editing the tomcat server.xml for both Server and Portal at Enterprise 11.5 on Windows, this does seem to just be that easy.

[BillMitchell]

Another reason it is important to add HTTP/2 support for the back-end services is that if the back-end is only HTTP/1.1 and the front-end server (load balancer) is HTTP/2, there are security issues that stem from that protocol downgrade.  Request smuggling and server desynchronization attacks may be feasible.

[BillMitchell]

We've been testing out the HTTP/2-enabled configuration for a few weeks and have had no issues.

The configuration change wasn't preserved through a 11.2->11.5 upgrade, but given that it's not officially supported this isn't surprising.  It was easy enough to make the change again at 11.5.

[DurmusCesar]

Agree above, ESRI SHOULD SUPPORT HTTP/2 properly across all their products that have web components/exposure either through adaptor or others...

[Geoeki]

I can only support that idea. Very surprised, Esri doesn't support this natively by 2026.

Supporting HTTP/2 in ArcGIS Enterprise would be a significant performance improvement, especially for modern web GIS applications like Experience Builder and custom web clients. HTTP/2 enables multiplexing, which means multiple requests can be handled over a single connection in parallel. This directly reduces latency and improves load times for map-heavy applications where dozens (or hundreds) of resources (tiles, layers, scripts,...) are requested simultaneously.

From an infrastructure perspective, HTTP/2 also reduces connection overhead on the server side, which can improve scalability under load.

[BillMitchell]

Although it isn't officially supported, here's the process to enable HTTP/2 yourself.  We've been running it now for months without any issues (though did need to manually re-enable it after upgrading to a newer version of ArcGIS Enterprise).