Apache Tomcat ProxyPass Problem

[Andre Buettemeyer]

Hi Community,

i have installed new AWI Tomcat servers. After configuring Apache ProxyPass and ProxyPassReverse I observed the following problem. 
One can open 5 tabs simultaneously in the browser and work with the AWI with good performance. If you now open one more tab, the 
performance drops drastically. With some more tabs (8 to 10) the error message "Failed to load the widgetset: ./VAADIN/widgetsets/UC4WebUIWidgetset/
UC4WebUIWidgetset.nocache.js?1605695495802" appears. Same behavior with NGINX.

Here is the rudimentary Apache configuration from my sandbox installation:

<VirtualHost *:80>
        ProxyPass / http://10.0.3.8:8080/
        ProxyPassReverse / http://10.0.3.8:8080/
</VirtualHost>

As described in the documentation, you should enable websockets for good performance. It took me quite a while to connect "good performance" with "more than 5 simultaneous connections". 

This configurations solved the problem:

<VirtualHost *:80>
        RewriteEngine on
        RewriteCond %{HTTP:Upgrade} =websocket [NC]
        RewriteRule /(.*) ws://10.0.3.8:8080/$1 [P,L]
        ProxyPass / http://10.0.3.8:8080/
        ProxyPassReverse / http://10.0.3.8:8080/
</VirtualHost>

For encrypted communication i use this rule.
 
RewriteRule /(.*) wss://10.0.3.8:8443/$1 [P,L]

Maybe someone will help this information.

Regards

André

[Jared Kessans]

I'm sure others might be able to provide more information, but from my understanding, HTTP/1.1 has a limitation and most browsers have a max of 6 connections to the same web servers and some older browsers have a limit of 2. 

We have seen the same thing you have where five are fine, but the sixth is just too much if connecting to the same Automation Engine.

I was just looking into the HTTP/2 which there has been another thread recently that mentions it and that it removes that limitation.  There are some other potential issues, but you might be able to try it out and see if it works for you.

Edit: Here's the link.  https://community.broadcom.com/enterprisesoftware/discussion/automic-awi-login-issue-session-expired