Hi Alex, doesn't all that polling you're doing introduce a lot of unnecessary requests to the server.
There can be up to 200 persons logged in at the same time at the site where I'm using websockets now, that would be 100 HTTP POSTS per second with full HTTP headers etc just to check for notifications that perhaps 1 or 2 of them would get per 10 seconds. See figure 3 here: http://www.websocket.org/quantum.html On Mon, Jul 14, 2014 at 2:44 PM, Alexander Burger <a...@software-lab.de> wrote: > Hi Henrik, > > first of all, thank you for the article and the good work! > > However, I must say that I have doubts about the benefits of WebSockets > in general. I cannot see that they are worth the overhead. > > > They introduce a complicated machinery, which is not just a simple > protocol extension, but a fundamental change in the HTTP transaction > principles. As that, it violates the PicoLisp philosophy of "minimizing > the number of concepts". > > Second, they require a browser which can handle them. This excludes, for > example, text browsers like 'w3m'. > > Third, I'm still waiting for the killer-application which really needs > them. All scenarios I have seen so far can be handled with the standard > PicoLisp framework much more easily - without explicit maintenance tasks > lile "clearing out disconnected clients" and "sending a ping ... to keep > the connection alive". All this is already done automatically. > > > To keep with the typical "realtime chat", a minimal setup could be: > > ######################################################################## > #!/usr/bin/pil > > (load "@lib/http.l" "@lib/xhtml.l" "@lib/form.l") > > (de chat () > (app) > (action > (html 0 "Chat" "@lib.css" NIL > (form NIL > (gui 'log '(+FileField) "chat.log" 60 20) > (--) > (gui 'msg '(+TextField) 60) > (gui '(+Click +Auto +Button) 2000 'This 2000 "Chat" > '(when (val> (: home msg)) > (out "+chat.log" (prinl @)) > (clr> (: home msg)) ) ) ) ) ) ) > > (server 8080 "!chat") > (wait) > ######################################################################## > > Put this into a file called "chat", set it to executable, and start it > as: > > $ ./chat > > Then point some browser windows to "http://localhost:8080";. Everything > typed into the 'msg' text field (and even in the 'log' field above it) > appears in all other connected clients after maximally 2 seconds. > > Note that also text browsers like w3m can be used. Just the automatic > firing of the button won't happen without JavaScript, so the user must > press the "Chat" button whenever he wants an update. Also note that due > to the same-origin-policy of JavaScrpt (repeatedly discussed here) the > "Chat" buttun must be pressed in the beginning once, unless - as usually > recommended - 'httpGate' is running and the client connected directly to > "http://localhost";. > > > Other features like a notification system can be implemented even > simpler. You could, for example, clone the existing 'ping' and '<ping>' > functions in "@lib/xhtml.l" and extend them to carry a payload. > > ♪♫ Alex > -- > UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
