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[REBOL] Re: Understanding tcp

From: Rebolinth:nodep:dds:nl at: 15-Aug-2003 19:39

-- Conversation/lunch: "How do you Eat your Rebol in the Morning?" Quoting patrick Hello Patrick, Here some tips programming servers under rebol, maybe usefull i dont know, but what i know is dat i had to rethink the rebol logic befor i was able to program servers in rebol...but finaly its easy ;-) Make sure what yuo want with your server when opening it: ie. lines based? binary based? blocking or non-blocking? (no-wait) direct? (which is default) Then when you setup a server under rebol like: server: open tcp://:listenport the server will listen on ALL nic's on your machine so the connection coming in could be on ANY ip address on that NIC. the server 'port is now opened and is ready to read incoming sessions, BUT when yuo have a tcp server make a selection to distinguish between the SERVER itself and or a NEW connection. that looks like this: connection: wait server ;; this wait for events on the server 'port when a session comes INto server the 'connection will be SERVER-PORT itself !!! (Depends if yuo have it all inside a forever loop with a wait inside!! because then you might split it with a "either equal? server conenction [yes then][ no then] or use dispatch or port/awake) do a "first" on "connection" and you will get the 'port information from the new remote-client!! like -> client: first connection This client 'port has information like client/remote-ip client/remote-port client/local-ip client/local-port and ie. client/state/flags Now you can read or write to THAT specific client, Still !! If client: first connection you can do read-io write-io on the client-server or insert copy anyting with block related ... STILL keep in mind, that tracking a remote-port disconnect is not possible in rebol, you can only check if the remote hung up by doing am action like insert, first copy on the client port befor you know its closed (irritating..) Anyway.. here my MULTI SESSION ECHHO SERVER ... enjoy, Norman. rebol [ author: "rebolinth nodep dds nl" version: "1.0" ] ports: [] ; ports we listen on clients: [] ; ip:port dbase listener: open/lines/direct tcp://:2000 ports: reduce [ 0:01 listener ] forever [ ;;; wait for 0:01 or ports event, use timer to prevent deadlocks, dispatch ;;; is an option perhpas here, or even WAIT awake port: wait ports if port [ either port = listener [ append ports new: first port print rejoin [ now " [NEW] " new/remote-ip ":" new/remote-port ] append/only clients rejoin [ new/remote-ip ":" new/remote-port ] insert new rejoin [ "Welcome " new/remote-ip ":" new/remote-port ] ][ ;;; try to read a line from the port, if error? then client is gone either error? try [ line: first port ] [ find clients rejoin [ port/remote-ip ":" port/remote-port ] print rejoin [ now " [DIS] " port/remote-ip ":" port/remote-port ] remove find ports port remove find clients rejoin [ port/remote-ip ":" port/remote-port ] ][ print rejoin [ now " [INC] " port/remote-ip ":" port/remote-port " > " line ] ;;; send all ports, because we read a line from one, to all foreach x next next ports [ insert x line ] ] ] ] ] close listener