> - spinning up a new chatting client goroutine (mainly the quoted code > in OP) when a new user logs in, then there will be a new net.Conn for > the client > - since I'm only doing server side programming and one server needs to > serve different clients, the only way I can think of is to store their > own net.Conn in their own cookies to track individual status > - to avoid users hitting refresh and losing all past conversations, I > think I have to store the conversation (since login) in cookies as > well.
Cases where the client echos back its connection are usually suspect since that's information the server already knows by virtue of receiving the request. It sounds like this is trying to use a transport layer construct as an application layer identifier, and it’ll likely be easier (and a better learning exercise) to use a proper application layer identifier instead. That’ll also sidestep a pile of edge cases. An interesting thing about browsers is that, in contrast to CLI client, mobile clients, etc., you have very little control over the connections themselves. You control the requests, and the browser is responsible for servicing it - it may close connections, open new connections, use multiple connections, and so on. It looks like you have a simulated login flow. One way this could work is by setting a session cookie after login - that gets you an application layer identifier that may map to one or multiple changing transport identifiers (net.Conns). You could then buffer unsent messages per session ID, send them regardless of what transport they come over, and delete buffers for old sessions after all their transports are closed and a timeout period has passed (which prevents the unbounded growth problem you’d mentioned). That’s close to how an actual system may work, with the big exception that in production the session ID must be encrypted server-side to prevent the client from tampering/spoofing (though that’s unnecessary for a learning demo). > Hmm... on second thought, since I'm planning to let users do their > manual refreshing, maybe store the whole conversation on the server > and when refresh, it prints from the 1st line again might be another > option. > > What would you think is the easiest thing to do here? Thanks! Manually refreshing and echoing back the conversation from the beginning sounds like a great first version to me! You may encounter some odd cases where the full chat history is echoed back or a client unexpectedly disconnects due to the whims of the browser’s connection pooling logic, but no big deal. If you finish that and are interested in learning more or making a second version, I’d then consider either going down the session ID path, or looking into WebSockets (which is what I meant to say earlier instead of WebTransport, oops - that’s a slightly different thing). WS would require a little client work, but would still be primarily server-side changes; it’s essentially a browser-supported API that gets you a TCP connection, so you could fully mimic the netcat behavior from the example. -eli >> On Jul 22, 2023, at 11:26 PM, Tong Sun <suntong...@gmail.com> wrote: >> >> I know web based chatting service can be as complicated as possible, but I >> want to build a web based chat server that is as simple as possible. >> >> And the chapter 8 of the book "The Go Programming Language" at >> https://github.com/adonovan/gopl.io/tree/master/ch8/chat >> seems to be a perfect starting point to learn the asynchronous web based >> chat service building. >> >> I've built a whole (simplest) web service that support user login and >> logout, at: >> https://github.com/suntong/lang/blob/master/lang/Go/src/net/HttpD/demo-redirect.go >> and was planning that the next logic steps would be to >> >> - incorporate the chat server as another goroutine besides my web server, and >> - add the chatting to my web service by spinning up a new chatting client >> goroutine when a new user logs in. >> >> However, it is incorporating the chatting client into my web service that >> made my head spinning none-stop. IE, for the following few lines of code from >> https://github.com/adonovan/gopl.io/blob/master/ch8/netcat3/netcat.go >> >> done := make(chan struct{}) >> go func() { >> io.Copy(os.Stdout, conn) // NOTE: ignoring errors >> log.Println("done") >> done <- struct{}{} // signal the main goroutine >> }() >> mustCopy(conn, os.Stdin) >> conn.Close() >> <-done // wait for background goroutine to finish >> >> I'm having a hard time putting it into my code. Specifically, how to handle >> incoming new chats message and push to all web base clients. What's the >> simplest solution for it? >> Note, to avoid user hitting refresh and lost all past conversation, I was >> planning to store all of them, including the connect variable returned from >> `net.Dial` into cookies. I know that there is a 4K size limit to total >> cookies size, but that's OK with me for such a simplest chatting service, >> which would add as minimum to the solution from ch8/chat as possible. >> >> Anybody can help please? >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/e3327bc2-4f2f-4038-b38d-0c9794ec6235n%40googlegroups.com. >> >> > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CAMmz1Ofwc1DY7U6Xbzq04KmD4%3DJaP632ZKP8N_NW7jwEnXTraQ%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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