SSE

[manson]

Hi!
I'm here with another issue. I've been playing lately with SSE and used you example:

// will be hitted every 1-2 sec, you can check anything if change and send data on the fly using c.StreamResponse
app.SSE("/sse/logs",func(c *kamux.Context) {
lenStream := len(logger.StreamLogs)
if lenStream > 0 {
	lastOne := lenStream-1
	err := c.StreamResponse(logger.StreamLogs[lastOne])
	if err == nil{
		logger.StreamLogs=[]string{}
	}
}
})

1. It's a bit old: now instead of StreamResponse the Stream is used. Now it looks like this:

sbus.App.SSE("/sse/logs",func(c *kmux.Context) {		
		lenStream := len(logger.StreamLogs)
		if lenStream > 0 {
			lastOne := lenStream-1
			lastLog := logger.StreamLogs[lastOne]
			c.Stream(lastLog)
                        return
		}
		c.Stream("")
	})

2. Logs in example could be lost if they appear faster than handler run period, but ok, this is only an example, but should be noted.
3. It's a bit strange way to periodically call sse handler - never met like this before, but ok, I even found this useful to make not direct call to Stream right away when data appeared but in time, filling a queue and later (1-3 seconds ok) send back. But exactly this example won't work - it will rise an exception on client side EventSource's response has a MIME type ("text/plain") that is not "text/event-stream". Aborting the connection.. This is if no logs exist. But if I put c.Stream("") in the end it will work ok and data will come to client, but if no data, it will send to client empty strings. This is not good. Wrong. Stream should result to client only when I want, when data exists, but not periodically. I.e. It's ok to periodically call a handler, but only I should decide whether to send back data or not in it.

Theoretically I could workaround this like in WS example - storing connection of caller and later send to stream, but in this case I cannot off this periodical handler calls. Besides, I suppose, you are already storing these connections to process periodic handler and additional copy I could do is not good.

So I think there needs to be made next changes:

1. Ability to off and on periodic sse handler call - sometimes it is useful, but sometimes not needed. Maybe 2 handlers? Usual and periodic?
2. Remove client-side exception if handler does not send back data to the stream during handler call. I don't exactly remember, but SSE is simple only at first glance - it has its internal mechanism to keep connection alive (reestablish connections, internal pings etc.), it checks if data lost during connection break by monitoring packet ID (on connection client sends last packet ID it received, and server resends packets starting from that id, etc.).

Without this It looks like SSE not much useful...

[kamalshkeir]

@manson Hi bro,
indeed SSE is less powerful than websockets, for instance sse can handle only 5 connections i think, and it's not me who is calling the handler, it is called every 1-2 seconds by the browser automatically (not sure but firefox also may have some different behavior like calling the endpoint more or less frequentily), this is how sse protocol is implemented, so it's like browser pooling for and endpoint that you cannot stop.
I think there is nothing you can do with SSE that you cannot do with a simple pooling or websockets, and it is used for push notifications usually, and overall my bus implemantation can make handling these ws connections way easier using the python, js, and go client in a pubsub style

[kamalshkeir]

@manson

updated version of kmux :

func WrapRegexParam(name, typeToValidate string) string {
	var wrappedString string
	switch typeToValidate {
	case "int":
		wrappedString = `(?P<` + name + `>\d+(?:-\d+)*)` //  '/name:int' can handle /2 /2-3 /2-3-4
	case "float":
		wrappedString = `(?P<` + name + `>[+-]?([0-9]*[.])?[0-9]+(?:[+-]?([0-9]*[.])?[0-9]+)*)` //  '/name:float' can handle /2.2 /2.2-3.3 /2.2-3.343-4
	case "any":
		wrappedString = `(?P<` + name + `>[^\/]+)` //  '/name:any' can handle all previous and in this case /favicon.ico
	default:
		wrappedString = `(?P<` + name + `>[a-z0-9]+(?:-[a-z0-9]+)*)` //  '/:name' no more str or string or slug, the default now is slug so it will work with /abc-123 but not with /favicon.ico and /abc-2.3
	}
	return wrappedString
}

this will not break previous use of /name:str or others
you can execute go get -u to update kmux

[manson]

@kamalshkeir
Thanks. I needed "any" as a parameter. Now it works in my routes, but admin part is broken - when entering to tables, it says "not found" :-(

[kamalshkeir]

@kamalshkeir
Thanks. I needed "any" as a parameter. Now it works in my routes, but admin part is broken - when entering to tables, it says "not found" :-(

ah, thanks, i will check it

[kamalshkeir]

@manson , fixed, go get -u , kmux is at version v1.9.2

[manson]

@manson , fixed, go get -u , kmux is at version v1.9.2

Thanks! Looks like it works now

[manson]

maybe i'm not understanding your problem, if so, give me an example
I needs param to be "abc" and "123-234" at the same route. I.e. - no limits. Well, letters, digits, and some meaningful chars (.-+^$#_=!@) Well, why cant it just be splitted by "/"? Say, if no type supplied "/:id" or "/id:any" so in this case just split by "/" and pass like that without regex?