IIS 8.5 ARR 3.0 Synchrony Websockets Reverse Proxy Action type Route to Server Farm

[ShipitSmarter]

Dear Community,

Attempting to implement Confluence 6.5 with Collaborative Editing feature.
Confluence is running on a VM behind a Reverse Proxy with IIS8.5/ARR3.0 which is on a separate VM. Because its not co-hosted we use web-farms. We host many other things, not just atlassian. In this case the used server-farm definition contains a single server only, that runs confluence.

Upon executing step by step the document: 
Proxying Atlassian server applications with Microsoft Internet Information Services (IIS)
https://confluence.atlassian.com/kb/proxying-atlassian-server-applications-with-microsoft-internet-information-services-iis-833931378.html

When creating the necessary URL rewrite rules, under Confluence 6.0 specific notes, i do not know how to implement rule = "Synchrony Web Sockets Reverse Proxy"

Normally i would use HTTP or HTTPS from the actions dropdown list, for example:
<action type="Rewrite" url="http://<server-farm>/{R:1}" />

where the custom port is set in the farm definition.

how ever the guide tells to use: 
<action type="Rewrite" url="ws://localhost:8091/{R:1}"

How can the web-sockets ws:// be routed to the designated server-farm?

[ShipitSmarter · Accepted solution]

Created a Farm as below:
<webFarm name="ConfluenceTest_Synchrony" enabled="true">
 <server address="10.0.0.1" enabled="true">
 <applicationRequestRouting httpPort="8091" />
</server>
</webFarm>

Configured it to use passthrough. Then the WebsSocket Rule:

<rule name="Confluence Synchrony Web Sockets Reverse Proxy" enabled="true" stopProcessing="true">
  <match url="ws://(.*)" />
  <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
  </conditions>
  <action type="Rewrite" url="http://ConfluenceTest_Synchrony/{R:1}" />
 </rule>

So ws:// can go to http://