Use websockets for events (Client limit)

[casdr]

We're having the issue that we want to run 8 dashboards at the same time. Due to the HTTP client limit, we have to open 2 different browsers to make this work.

Switching to websockets seems like a good idea, first of all it's better for the use case and websockets don't have a client limit.

[terraboops]

You will hit the same browser-side connection limit. HTTP/2 should fix the issue you are seeing. Until then, it's domain sharding for you.

There may be other good reasons to switch to WebSockets, but this is not one IMHO.

Source:
http://www.browserscope.org/?category=network

On Jun 20, 2016, at 3:16 AM, Cas de Reuver notifications@github.com wrote:

We're having the issue that we want to run 8 dashboards at the same time. Due to the HTTP client limit, we have to open 2 different browsers to make this work.

Switching to websockets seems like a good idea, first of all it's better for the use case and websockets don't have a client limit.

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[casdr]

Ah, seems like the article I read was wrong. Then I'll stay with running 2 seperate browsers :)

[terraboops]

You can also use a technique called domain sharding. Add DNS entries to your DNS server or local hosts file that all point to the same server. The browser-side limitation is not smart and relies entirely on hostname matching, so it is easy to fool.

For example:

/etc/hosts or c:\Windows\System32\Drivers\etc\hosts

127.0.0.1 dashing-server1
127.0.0.1 dashing-server2
127.0.0.1 dashing-server3

Then you can open 6-10 tabs on each "server" by it's hostname (depending on browser).

http://dashing-server1
http://dashing-server2
http://dashing-server3

[terraboops]

I'll leave this ticket open for a while, in case anybody wants to discuss moving WebSockets for other reasons.

[tokudan]

Why not use Firefox and change the following setting in about:config?
network.http.max-persistent-connections-per-server (default 6, set to e.g. 15)

[kinow]

@tokudan sometimes changes in the browser are not possible. e.g. when someone from another company, or even an executive, or someone without technical skills need to access the dashboard. Would be nice to have a solution without the user having to change any setting in his browser.

[terraboops]

Sometimes a browser change is possible, and I didn't know that this could be done. Thanks for the tip @tokudan!

The only solution to this is domain sharding. On further contemplation, HTTP/2 likely will not solve this problem. WebSockets, I know from experience, suffer the same problem. If you need to make this executive-proof, then use another page that does a 301 redirect or good-old-HTML meta refresh to the sharded domain (dashing-1.dashing.board, dashing-2.dashing.board, etc).

Another option - that is just crazy enough to fix this - would be for new tabs to discover and communicate with the parent window via postMessage, so that the first tab opened would essentially multiplex the connection (SSE or WebSocket). This vastly increases complexity of the base solution, but it would be interesting to add this as a component or dashing-contrib gem. Unfortunately, the current design of Dashing makes it hard to extend or modify core functionality like this (ie: how do you monkey-patch this). This, and many other parts of Dashing, could be refactored to be more extensible.

I am closing this, there are two reasonable solutions suggested. I have linked to this in the Wiki.