Matthew R. Wilson
b6fa48f37f
This is a relatively big new feature, which introduces small breaking changes to the API: * NegotiateTelnet() now returns (DevInfo, error) instead of just error. The function signature for the Tx type now has one additional DevInfo parameter. * RunTransactions() requires one additional parameter, the DevInfo (which is allowed to be nil). Otherwise, existing behavior continues to work as-is and everything still defaults to operating on the default 24x80 terminal size. See example5 for a larger-terminal-aware application. Pending some time to make sure no new bugs cropped up in this release and that the alternate screen size support works in the wild, I anticipate this will become the v1.0.0 release of go3270.
89 lines
1.9 KiB
Go
89 lines
1.9 KiB
Go
// This file is part of https://github.com/racingmars/go3270/
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// Copyright 2025 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 using the RunTransactions() approach to
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// structuring a go3270 application.
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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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"sync"
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"github.com/racingmars/go3270"
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)
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type global struct {
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usercount int // number of connected users
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countlock sync.Mutex
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}
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// session is the structure which holds global state for a user session of our
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// application. The various Transactions will be methods on this struct.
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type session struct {
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db DB
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user User
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// We can also share global state between users
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g *global
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}
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func main() {
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// "Connect" to our database (for this example, it's just a mock in-memory
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// database).
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dbconn := Connect()
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gblstate := new(global)
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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, dbconn, gblstate)
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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, db DB, gblstate *global) {
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defer conn.Close()
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// Create the state for this client's connection
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state := session{
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db: db,
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g: gblstate,
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}
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// Add to the global user counter
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gblstate.countlock.Lock()
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gblstate.usercount++
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gblstate.countlock.Unlock()
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// When the session ends, reduce the user count
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defer func() {
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gblstate.countlock.Lock()
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gblstate.usercount--
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gblstate.countlock.Unlock()
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}()
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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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err = go3270.RunTransactions(conn, devinfo, state.login, nil)
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if err != nil {
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fmt.Println(err)
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}
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}
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