Prototype state flow in F#

Broker peering simulation (part 1)
Prototypes the state flow

#r @"bin/fszmq.dll"
#r @"bin/fszmq.devices.dll"
open fszmq
open fszmq.Context
open fszmq.devices
open fszmq.Polling
open fszmq.Socket

#load "zhelpers.fs"

let main args =
// first argument is this broker's name
// other arguments are our peers' names
match args |> Array.length with
| n when n > 1 ->
let rand = srandom()
let self = args.[1]
printfn "I: preparing broker at %s…" self

// prepare our context and sockets
use ctx = new Context(1)
use statebe = ctx |> pub
bind statebe (sprintf "tcp://*:%s" self)
//NOTE: to run this example on Windows, we must use tcp
// so when we do, assume inputs are port numbers
// on non-windows systems, we can use ipc (as per the guide)…
// so in *that* case, inputs are alphanumeric identifiers, eg:
// bind statebe (sprintf "ipc://%s-state.ipc" self)

// connect statefe to all peers
use statefe = ctx |> sub
[""B] |> subscribe statefe
args.[2..] |> Array.iter (fun peer ->
printfn "I: connecting to state backend at '%s'" peer
connect statefe (sprintf "tcp://localhost:%s" peer))
//NOTE: see previous note about Windows and ipc vs. tcp

// send out status messages to peers, and collect from peers
// the zmq_poll timeout defines our own heartbeating
let items =
[ Poll(ZMQ.POLLIN,statefe,fun _ ->
let peer_name = statefe |> recv |> decode
let available = statefe |> recv |> decode
printfn "%s - %s workers free" peer_name available) ]
while true do
if not (items |> poll 10000L) then
// send random value for worker availability
statebe <~| (encode self)
<<| (rand.Next(0,10) |> string |> encode)

| _ ->
printfn "syntax: peering1 me {you}…"

main fsi.CommandLineArgs