118 lines
2.9 KiB
Go
118 lines
2.9 KiB
Go
// This file is part of https://github.com/racingmars/go3270/
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// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
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// LICENSE in the project root for license information.
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// This example demonstrates updating portions of the screen while waiting
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// for a client response.
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package main
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import (
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"fmt"
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"net"
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"time"
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"github.com/racingmars/go3270"
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)
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var screen = go3270.Screen{
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{Row: 0, Col: 35, Intense: true, Content: "3270 Clock"},
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{Row: 1, Col: 0, Color: go3270.White,
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Content: "------------------------------------------------------------------------------"},
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{Row: 5, Col: 5, Color: go3270.Turquoise, Content: "The current UTC time is:"},
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{Row: 5, Col: 30, Color: go3270.Yellow, Intense: true, Content: "XX:XX:XX"},
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{Row: 22, Col: 0, Content: "PF3 Exit"},
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}
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var refresh = go3270.Screen{
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screen[3], // Copy the time field that we want to update
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}
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func main() {
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ln, err := net.Listen("tcp", ":3270")
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if err != nil {
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panic(err)
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}
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fmt.Println("LISTENING ON PORT 3270 FOR CONNECTIONS")
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fmt.Println("Press Ctrl-C to end server.")
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for {
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conn, err := ln.Accept()
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if err != nil {
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panic(err)
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}
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go handle(conn)
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}
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}
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// handle is the handler for individual user connections.
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func handle(conn net.Conn) {
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defer conn.Close()
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// Always begin new connection by negotiating the telnet options
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devinfo, err := go3270.NegotiateTelnet(conn)
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if err != nil {
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fmt.Println(err)
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return
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}
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// First, let's send the initial screen and wait forever for the user to
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// press PF3, and when we get it, send a message on the done channel.
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done := func() chan bool {
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done := make(chan bool)
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// This will run in a goroutine so it can block waiting for the
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// response, while the rest of the code below (which refreshes the
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// screen every second) can continue to run.
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go func() {
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// Loop forever, sending the background screen until user exits.
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for {
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screen[3].Content = time.Now().UTC().Format("15:04:05")
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response, err := go3270.ShowScreenOpts(screen, nil, conn,
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go3270.ScreenOpts{
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CursorRow: 23,
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CursorCol: 0,
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Codepage: devinfo.Codepage(),
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})
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if err != nil {
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// User dropped connection, maybe? We'll end things.
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done <- true
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return
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}
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if response.AID == go3270.AIDPF3 {
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// User wants to quit.
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done <- true
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return
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}
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}
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}()
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return done
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}()
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ticker := time.NewTicker(time.Second)
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defer ticker.Stop()
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for {
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select {
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case <-done:
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// User pressed PF3 (or we need to quit for some other reason)
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return
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case <-ticker.C:
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// Send the updated time, without clearing the screen
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refresh[0].Content = time.Now().UTC().Format("15:04:05")
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_, err := go3270.ShowScreenOpts(refresh, nil, conn,
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go3270.ScreenOpts{
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NoClear: true,
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NoResponse: true,
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Codepage: devinfo.Codepage(),
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})
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if err != nil {
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// Bail out
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return
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}
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}
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}
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}
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