Re: A talk on Lua: Our experience with LuaJIT in mid-load web-projects (in Russian)

[Tim Mensch <tim-lua-l@...>]

On 5/24/2013 9:23 AM, Daurnimator wrote:
> How is long polling a problem? 

I was under the impression they were using OpenResty, though apparently 
they weren't, and they listed long polling as a "problem" on the slides, 
so I was wondering if they'd since found a solution.

I guess the only problem I'm aware of is that there isn't a nice 
prepackaged library that handles long polling ("Comet" [1] -- something 
like socket.io [2]) reliably across browsers. Ideally there would be a 
WebSocket code path as well. A bit of Googling finds a module for Nginx 
that supports websockets [3], but with no OpenResty support available.

So it looks like my current solution would be one of :

1) Stick with simple long polling in OpenResty and implement the 
handling myself entirely in JavaScript. I'd rather not, since even 
though long polling isn't exactly rocket science, it strikes me as 
something prone to browser-specific issues. Additionally, I'm led to 
believe the server load is higher with long polling than with 
WebSockets, and I know the latency isn't as good if two messages arrive 
in quick succession.

2) Switch to Mongrel2/Tir from OpenResty, though it's not clear to me 
that Tir support for WebSockets is first class yet. Documentation is 
nonexistent, as far as I can tell, and support for existing JavaScript 
libraries is an unknown.

3) Switch to Node.js so I can use socket.io without having to reinvent 
the server or client side of that equation.

#s 1 and 2 keep me with Lua, which is important to me, but if it turns 
out that #3 gives me significantly better scalability on a single server 
(through the use of WebSockets), then I'll swallow my dislike of JS and 
use it. #3 sounds like the "it just works" solution, which is very 
attractive.

Tim


[1] http://en.wikipedia.org/wiki/Comet_%28programming%29

[2] http://socket.io/

[3] https://github.com/wandenberg/nginx-push-stream-module