Add RunTransactions() approach to application design

example4/database.go

@@ -0,0 +1,96 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2025 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+// This example demonstrates using the RunTransactions() approach to
+// structuring a go3270 application.
+
+// This file contains a mock in-memory database for the purposes of our
+// example application.
+
+package main
+
+import (
+	"errors"
+	"sync"
+	"time"
+)
+
+type User struct {
+	Username   string
+	Password   string
+	Name       string
+	SignupDate time.Time
+}
+
+type DB interface {
+	GetUser(username string) (User, error)
+	CreateUser(user User) (User, error)
+	UpdateUser(user User) (User, error)
+}
+
+type dbstate struct {
+	lock  sync.Mutex
+	users map[string]User
+}
+
+func Connect() DB {
+	return &dbstate{
+		users: make(map[string]User),
+	}
+}
+
+var ErrUserExists = errors.New("username already exists")
+var ErrNotFound = errors.New("record not found")
+
+func (db *dbstate) GetUser(username string) (User, error) {
+	db.lock.Lock()
+	defer db.lock.Unlock()
+
+	user, ok := db.users[username]
+	if !ok {
+		return User{}, ErrNotFound
+	}
+
+	return user, nil
+}
+
+func (db *dbstate) CreateUser(user User) (User, error) {
+	db.lock.Lock()
+	defer db.lock.Unlock()
+
+	if _, ok := db.users[user.Username]; ok {
+		return User{}, ErrUserExists
+	}
+
+	user.SignupDate = time.Now().UTC().Truncate(time.Second)
+
+	// Obviously in a real application you wouldn't store plaintext password,
+	// but this is a simple example for the purposes of demonstrating go3270,
+	// not demonstrating how to build a secure application.
+	db.users[user.Username] = user
+
+	return user, nil
+}
+
+func (db *dbstate) UpdateUser(user User) (User, error) {
+	db.lock.Lock()
+	defer db.lock.Unlock()
+
+	olduser, ok := db.users[user.Username]
+	if !ok {
+		return User{}, ErrNotFound
+	}
+
+	// Make sure original signup date is maintained
+	user.SignupDate = olduser.SignupDate
+
+	// Carry over existing password if we aren't setting a new password
+	if user.Password == "" {
+		user.Password = olduser.Password
+	}
+
+	db.users[user.Username] = user
+
+	return user, nil
+}

example4/example4.go

@@ -0,0 +1,83 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2025 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+// This example demonstrates using the RunTransactions() approach to
+// structuring a go3270 application.
+
+package main
+
+import (
+	"fmt"
+	"net"
+	"sync"
+
+	"github.com/racingmars/go3270"
+)
+
+type global struct {
+	usercount int // number of connected users
+	countlock sync.Mutex
+}
+
+// session is the structure which holds global state for a user session of our
+// application. The various Transactions will be methods on this struct.
+type session struct {
+	db   DB
+	user User
+
+	// We can also share global state between users
+	g *global
+}
+
+func main() {
+	// "Connect" to our database (for this example, it's just a mock in-memory
+	// database).
+	dbconn := Connect()
+
+	gblstate := new(global)
+
+	ln, err := net.Listen("tcp", ":3270")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println("LISTENING ON PORT 3270 FOR CONNECTIONS")
+	fmt.Println("Press Ctrl-C to end server.")
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			panic(err)
+		}
+		go handle(conn, dbconn, gblstate)
+	}
+}
+
+// handle is the handler for individual user connections.
+func handle(conn net.Conn, db DB, gblstate *global) {
+	defer conn.Close()
+
+	// Create the state for this client's connection
+	state := session{
+		db: db,
+		g:  gblstate,
+	}
+
+	// Add to the global user counter
+	gblstate.countlock.Lock()
+	gblstate.usercount++
+	gblstate.countlock.Unlock()
+
+	// When the session ends, reduce the user count
+	defer func() {
+		gblstate.countlock.Lock()
+		gblstate.usercount--
+		gblstate.countlock.Unlock()
+	}()
+
+	// Always begin new connection by negotiating the telnet options
+	go3270.NegotiateTelnet(conn)
+	err := go3270.RunTransactions(conn, state.login, nil)
+	if err != nil {
+		fmt.Println(err)
+	}
+}

example4/help.go

@@ -0,0 +1,68 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2025 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+// This example demonstrates using the RunTransactions() approach to
+// structuring a go3270 application.
+
+// This file contains the help transaction generator.
+
+package main
+
+import (
+	"net"
+
+	"github.com/racingmars/go3270"
+)
+
+var helpScreen = go3270.Screen{
+	{Row: 0, Col: 45, Intense: true, Content: "Online Help"},
+
+	{Row: 2, Col: 0,
+		Content: "This help screen is an example of a transaction that"},
+	{Row: 3, Col: 0,
+		Content: "can be used as the next transaction from many other transactions"},
+	{Row: 4, Col: 0, Content: "and returns to the transaction that called it."},
+
+	{Row: 6, Col: 0, Content: "Press"},
+	{Row: 6, Col: 6, Content: "PF3", Color: go3270.White, Intense: true},
+	{Row: 6, Col: 10,
+		Content: "to return to the transaction from which you came."},
+
+	// Error message
+	{Row: 21, Col: 0, Name: "errormsg", Color: go3270.Red, Intense: true},
+
+	// Key legend
+	{Row: 23, Col: 1, Content: "F3=Exit"},
+}
+
+// The help transaction is an example of returning a closure over a parameter,
+// in this case the desired next transaction. This allows us to use the same
+// transaction from multiple other transactions and return to the requested
+// transaction when the user leaves the help transaction.
+//
+// Any data passed to help will be passed back to the transaction it returns
+// to.
+//
+// The help transaction has no need for any global or session state, so this
+// generator function for it is a stand-alone function and not a method on the
+// session.
+func help(returnTransaction go3270.Tx) go3270.Tx {
+	return func(conn net.Conn, data any) (go3270.Tx, any, error) {
+		_, err := go3270.HandleScreen(
+			helpScreen,                  // the screen to display
+			nil,                         // (no) rules to enforce
+			nil,                         // pre-populated values in fields
+			[]go3270.AID{go3270.AIDPF3}, // keys we accept
+			nil,
+			"errormsg", // name of field to put error messages in
+			23, 79,     // cursor coordinates
+			conn)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		// Any accepted key returns to the requested returnTransaction
+		return returnTransaction, data, nil
+	}
+}

example4/login.go

@@ -0,0 +1,257 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2025 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+// This example demonstrates using the RunTransactions() approach to
+// structuring a go3270 application.
+
+// This file contains the login and user registration transactions.
+
+package main
+
+import (
+	"net"
+
+	"github.com/racingmars/go3270"
+)
+
+const loginUsername = "username"
+const loginPassword = "password"
+const loginPasswordConf = "password confirmation"
+const loginName = "name"
+const loginErr = "errormsg"
+
+var loginScreen = go3270.Screen{
+	{Row: 0, Col: 37, Intense: true, Content: "Logon"},
+	{Row: 2, Col: 0,
+		Content: "Welcome to the go3270 example application. Please log on."},
+
+	// Username
+	{Row: 4, Col: 0, Content: "Username . . .", Color: go3270.Green},
+	{Row: 4, Col: 15, Name: loginUsername, Write: true,
+		Highlighting: go3270.Underscore, Color: go3270.Turquoise},
+	{Row: 4, Col: 24, Autoskip: true}, // field "stop" character
+
+	// Password
+	{Row: 5, Col: 0, Content: "Password . . .", Color: go3270.Green},
+	{Row: 5, Col: 15, Name: loginPassword, Write: true, Hidden: true},
+	{Row: 5, Col: 79}, // field "stop" character
+
+	// Registration instructions
+	{Row: 7, Col: 0, Content: "If you don't yet have an account, press"},
+	{Row: 7, Col: 40, Content: "PF5", Color: go3270.White, Intense: true},
+	{Row: 7, Col: 44, Content: "to register a new account."},
+
+	// Error message
+	{Row: 21, Col: 0, Name: loginErr, Color: go3270.Red, Intense: true},
+
+	// Key legend
+	{Row: 23, Col: 1, Content: "F1=Help"},
+	{Row: 23, Col: 14, Content: "F3=Exit"},
+	{Row: 23, Col: 27, Content: "F5=Register"},
+}
+
+var loginScreenRules = go3270.Rules{
+	loginUsername: {Validator: go3270.NonBlank},
+	loginPassword: {Validator: go3270.NonBlank, Reset: true},
+}
+
+// login transaction accepts a string value in data if the login screen
+// should be initialized with an error message.
+func (sess *session) login(conn net.Conn, data any) (go3270.Tx, any, error) {
+
+	fieldValues := make(map[string]string)
+
+	if data != nil {
+		if errmsg, ok := data.(string); ok {
+			fieldValues[loginErr] = errmsg
+		}
+	}
+
+	resp, err := go3270.HandleScreen(
+		loginScreen,                   // the screen to display
+		loginScreenRules,              // the rules to enforce
+		fieldValues,                   // pre-populated values in fields
+		[]go3270.AID{go3270.AIDEnter}, // keys we accept -- validating
+		[]go3270.AID{ // keys we accept -- non-validating
+			go3270.AIDPF1,
+			go3270.AIDPF3,
+			go3270.AIDPF5,
+			go3270.AIDClear},
+		loginErr, // name of field to put error messages in
+		4, 16,    // cursor coordinates
+		conn)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	switch resp.AID {
+	case go3270.AIDClear:
+		// re-run the transaction with empty values
+		return sess.login, nil, nil
+	case go3270.AIDPF1:
+		// Display help transaction, then return to this transaction
+		return help(sess.login), nil, nil
+	case go3270.AIDPF3:
+		// User wants to quit; return no next transaction
+		return nil, nil, nil
+	case go3270.AIDPF5:
+		// Send user to registration transaction
+		return sess.newuser, nil, nil
+	}
+
+	// If we didn't get one of the other allowed keys, try to log the user in.
+	username := resp.Values[loginUsername]
+	password := resp.Values[loginPassword]
+
+	user, err := sess.db.GetUser(username)
+	// NOTE: this is just an example application. Obviously in a real
+	// application, password hashing would be in place.
+	if err != nil || user.Password != password {
+		// If we couldn't get the username from the DB, or if the password
+		// doesn't match, re-run the login transaction with an error
+		// message displayed.
+
+		return sess.login, "Username or password not valid.", nil
+	}
+
+	// Login was successful. Update the session state to the logged-in user.
+	sess.user = user
+
+	return sess.mainmenu, nil, nil
+}
+
+var newuserScreen = go3270.Screen{
+	{Row: 0, Col: 30, Intense: true, Content: "New User Registration"},
+	{Row: 2, Col: 0,
+		Content: "Please provide your user registration details."},
+
+	// Username
+	{Row: 4, Col: 0, Content: "Username . . .", Color: go3270.Green},
+	{Row: 4, Col: 15, Name: loginUsername, Write: true,
+		Highlighting: go3270.Underscore, Color: go3270.Turquoise},
+	{Row: 4, Col: 24, Autoskip: true}, // field "stop" character
+
+	// Password
+	{Row: 5, Col: 0, Content: "Password . . .", Color: go3270.Green},
+	{Row: 5, Col: 15, Name: loginPassword, Write: true, Hidden: true},
+	{Row: 5, Col: 79, Autoskip: true}, // field "stop" character
+
+	// Password
+	{Row: 6, Col: 0, Content: "Confirm Pass .", Color: go3270.Green},
+	{Row: 6, Col: 15, Name: loginPasswordConf, Write: true, Hidden: true},
+	{Row: 6, Col: 79, Autoskip: true}, // field "stop" character
+
+	// Name
+	{Row: 7, Col: 0, Content: "Name . . . . .", Color: go3270.Green},
+	{Row: 7, Col: 15, Name: loginName, Write: true,
+		Highlighting: go3270.Underscore, Color: go3270.Turquoise},
+	{Row: 7, Col: 46, Autoskip: true}, // field "stop" character
+
+	// Error message
+	{Row: 21, Col: 0, Name: loginErr, Color: go3270.Red, Intense: true},
+
+	// Key legend
+	{Row: 23, Col: 1, Content: "F1=Help"},
+	{Row: 23, Col: 14, Content: "F3=Exit"},
+}
+
+var newuserScreenRules = go3270.Rules{
+	loginUsername:     {Validator: go3270.NonBlank},
+	loginPassword:     {Validator: go3270.NonBlank, Reset: true},
+	loginPasswordConf: {Validator: go3270.NonBlank, Reset: true},
+}
+
+// newuserData is the data that can be passed into the newuser transaction
+type newuserData struct {
+	username string
+	name     string
+	errmsg   string
+}
+
+func (sess *session) newuser(conn net.Conn, data any) (go3270.Tx, any, error) {
+
+	fieldValues := make(map[string]string)
+
+	if data != nil {
+		if newdata, ok := data.(newuserData); ok {
+			fieldValues[loginUsername] = newdata.username
+			fieldValues[loginName] = newdata.name
+			fieldValues[loginErr] = newdata.errmsg
+		}
+	}
+
+	resp, err := go3270.HandleScreen(
+		newuserScreen,                 // the screen to display
+		newuserScreenRules,            // the rules to enforce
+		fieldValues,                   // pre-populated values in fields
+		[]go3270.AID{go3270.AIDEnter}, // keys we accept -- validating
+		[]go3270.AID{ // keys we accept -- non-validating
+			go3270.AIDPF1,
+			go3270.AIDPF3,
+			go3270.AIDClear,
+		},
+		loginErr, // name of field to put error messages in
+		4, 16,    // cursor coordinates
+		conn)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	switch resp.AID {
+	case go3270.AIDClear:
+		// Re-run transaction with empty values
+		return sess.newuser, nil, nil
+	case go3270.AIDPF1:
+		// Display help screen, returning to this transaction after
+		return help(sess.newuser), nil, nil
+	case go3270.AIDPF3:
+		// User wants to cancel registration, go back to login screen.
+		return sess.login, nil, nil
+	}
+
+	// Otherwise, we'll try creating the user.
+
+	username := resp.Values[loginUsername]
+	password := resp.Values[loginPassword]
+	passwordConf := resp.Values[loginPasswordConf]
+	name := resp.Values[loginName]
+
+	if password != passwordConf {
+		// Re-run the newuser transaction with an error message
+		return sess.newuser, newuserData{
+			username: username,
+			name:     name,
+			errmsg:   "Passwords do not match.",
+		}, nil
+	}
+
+	user, err := sess.db.CreateUser(User{
+		Username: username,
+		Password: password,
+		Name:     name,
+	})
+
+	if err == ErrUserExists {
+		// Re-run the newuser transaction with an error message
+		return sess.newuser, newuserData{
+			username: username,
+			name:     name,
+			errmsg:   "Username already exists; please choose a new one.",
+		}, nil
+	}
+
+	if err != nil {
+		return sess.newuser, newuserData{
+			username: username,
+			name:     name,
+			errmsg:   "Unknown error creating new user.",
+		}, nil
+	}
+
+	// Success! We'll stick the new user in the session state like login does
+	// and go to the main menu.
+	sess.user = user
+
+	return sess.mainmenu, nil, nil
+}

example4/mainmenu.go

@@ -0,0 +1,232 @@
+// This file is part of https://github.com/racingmars/go3270/
+// Copyright 2025 by Matthew R. Wilson, licensed under the MIT license. See
+// LICENSE in the project root for license information.
+
+// This example demonstrates using the RunTransactions() approach to
+// structuring a go3270 application.
+
+// This file contains the main menu and the example placeholder features
+// of the application.
+
+package main
+
+import (
+	"net"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/racingmars/go3270"
+)
+
+const mainmenuOption = "option"
+const mainmenuUsername = "username"
+const mainmenuTime = "time"
+const mainmenuUsers = "users"
+const mainmenuError = "errormsg"
+
+var mainmenuScreen = go3270.Screen{
+	{Row: 0, Col: 31, Intense: true, Content: "Main Menu"},
+
+	// Option
+	{Row: 1, Col: 0, Content: "Option ===>", Color: go3270.Green},
+	{Row: 1, Col: 12, Name: mainmenuOption, Write: true,
+		Highlighting: go3270.Underscore, Color: go3270.Turquoise},
+	{Row: 1, Col: 79, Autoskip: true}, // field "stop" character
+
+	// Info
+	{Row: 3, Col: 57, Content: "User ID . :", Color: go3270.Green},
+	{Row: 3, Col: 69, Name: mainmenuUsername, Color: go3270.Turquoise},
+	{Row: 4, Col: 57, Content: "Time. . . :", Color: go3270.Green},
+	{Row: 4, Col: 69, Name: mainmenuTime, Color: go3270.Turquoise},
+	{Row: 5, Col: 57, Content: "Users . . :", Color: go3270.Green},
+	{Row: 5, Col: 69, Name: mainmenuUsers, Color: go3270.Turquoise},
+
+	// Options
+	{Row: 3, Col: 0, Content: "1", Color: go3270.White},
+	{Row: 3, Col: 3, Content: "Feature 1",
+		Color: go3270.Turquoise, Intense: true},
+	{Row: 3, Col: 17, Content: "A very cool feature", Color: go3270.Green},
+
+	{Row: 4, Col: 0, Content: "2", Color: go3270.White},
+	{Row: 4, Col: 3, Content: "Feature 2",
+		Color: go3270.Turquoise, Intense: true},
+	{Row: 4, Col: 17, Content: "Another neat feature", Color: go3270.Green},
+
+	{Row: 5, Col: 0, Content: "3", Color: go3270.White},
+	{Row: 5, Col: 3, Content: "Feature 3",
+		Color: go3270.Turquoise, Intense: true},
+	{Row: 5, Col: 17, Content: "This one's a boring feature",
+		Color: go3270.Green},
+
+	{Row: 7, Col: 5, Content: "Enter", Color: go3270.Green},
+	{Row: 7, Col: 11, Content: "X", Color: go3270.Turquoise, Intense: true},
+	{Row: 7, Col: 13, Content: "to log off and exit.", Color: go3270.Green},
+
+	// Error message
+	{Row: 21, Col: 0, Name: mainmenuError, Color: go3270.Red, Intense: true},
+
+	// Key legend
+	{Row: 23, Col: 1, Content: "F1=Help"},
+	{Row: 23, Col: 14, Content: "F3=Exit"},
+	{Row: 23, Col: 27, Content: "F5=Refresh"},
+}
+
+type mainmenuData struct {
+	option string // pre-populated option field value
+	errmsg string // error message to display
+}
+
+// mainmenu transaction accepts a mainmenuData struct as the data if the
+// option field or error message should be populated.
+func (sess *session) mainmenu(conn net.Conn, data any) (go3270.Tx, any, error) {
+
+	fieldValues := make(map[string]string)
+
+	if data != nil {
+		if d, ok := data.(mainmenuData); ok {
+			fieldValues[mainmenuOption] = d.option
+			fieldValues[mainmenuError] = d.errmsg
+		}
+	}
+
+	fieldValues[mainmenuUsername] = strings.ToUpper(sess.user.Username)
+	fieldValues[mainmenuTime] = time.Now().UTC().Format("15:04:05")
+	fieldValues[mainmenuUsers] = strconv.Itoa(sess.g.usercount)
+
+	resp, err := go3270.HandleScreen(
+		mainmenuScreen,                // the screen to display
+		nil,                           // (no) rules to enforce
+		fieldValues,                   // pre-populated values in fields
+		[]go3270.AID{go3270.AIDEnter}, // keys we accept -- validating
+		[]go3270.AID{ // keys we accept -- non-validating
+			go3270.AIDPF1,
+			go3270.AIDPF3,
+			go3270.AIDPF5,
+		},
+		mainmenuError, // name of field to put error messages in
+		1, 13,         // cursor coordinates
+		conn)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	switch resp.AID {
+	case go3270.AIDPF1:
+		// Display help, then return to this transaction
+		return help(sess.mainmenu), nil, nil
+	case go3270.AIDPF3:
+		// Exit
+		return nil, nil, nil
+	case go3270.AIDPF5:
+		// Refresh
+		return sess.mainmenu, nil, nil
+	}
+
+	// Handle the available options:
+	switch resp.Values[mainmenuOption] {
+	case "1":
+		return sess.exampleFeature,
+			"This is feature 1, a very cool feature.", nil
+	case "2":
+		return sess.exampleFeature,
+			"This is feature 2, another neat feature.", nil
+	case "3":
+		return sess.exampleFeature,
+			"This is feature 3, which is a boring one.", nil
+	case "x", "X":
+		// As if user hit PF3; exit
+		return nil, nil, nil
+	case "":
+		// As if user hit PF5, refresh
+		return sess.mainmenu, nil, nil
+	default:
+		// Run the transaction again with an error message
+		return sess.mainmenu,
+			mainmenuData{
+				option: resp.Values[mainmenuOption],
+				errmsg: "Unknown option",
+			}, nil
+	}
+}
+
+const featureMessage = "message"
+
+var exampleScreen = go3270.Screen{
+	{Row: 0, Col: 30, Intense: true, Content: "Application Feature"},
+
+	// Info -- replicate the data shown on the main menu
+	{Row: 3, Col: 57, Content: "User ID . :", Color: go3270.Green},
+	{Row: 3, Col: 69, Name: mainmenuUsername, Color: go3270.Turquoise},
+	{Row: 4, Col: 57, Content: "Time. . . :", Color: go3270.Green},
+	{Row: 4, Col: 69, Name: mainmenuTime, Color: go3270.Turquoise},
+	{Row: 5, Col: 57, Content: "Users . . :", Color: go3270.Green},
+	{Row: 5, Col: 69, Name: mainmenuUsers, Color: go3270.Turquoise},
+
+	// Feature-specific message
+	{Row: 12, Col: 0, Name: featureMessage},
+
+	{Row: 14, Col: 0, Content: "Press"},
+	{Row: 14, Col: 6, Content: "PF3", Intense: true, Color: go3270.White},
+	{Row: 14, Col: 10, Content: "to return to the main menu."},
+
+	// Error message
+	{Row: 21, Col: 0, Name: mainmenuError, Color: go3270.Red, Intense: true},
+
+	// Key legend
+	{Row: 23, Col: 1, Content: "F1=Help"},
+	{Row: 23, Col: 14, Content: "F3=Exit"},
+	{Row: 23, Col: 27, Content: "F5=Refresh"},
+}
+
+// exampleFeature is a transaction that will act as a placeholder for real
+// application functionality. It accepts a string in the data which will
+// be displayed on the panel.
+func (sess *session) exampleFeature(conn net.Conn, data any) (go3270.Tx,
+	any, error) {
+
+	fieldValues := make(map[string]string)
+
+	if data != nil {
+		if message, ok := data.(string); ok {
+			fieldValues[featureMessage] = message
+		}
+	}
+
+	fieldValues[mainmenuUsername] = strings.ToUpper(sess.user.Username)
+	fieldValues[mainmenuTime] = time.Now().UTC().Format("15:04:05")
+	fieldValues[mainmenuUsers] = strconv.Itoa(sess.g.usercount)
+
+	resp, err := go3270.HandleScreen(
+		exampleScreen, // the screen to display
+		nil,           // (no) rules to enforce
+		fieldValues,   // pre-populated values in fields
+		nil,           // keys we accept -- validating
+		[]go3270.AID{ // keys we accept -- non-validating
+			go3270.AIDPF1,
+			go3270.AIDPF3,
+			go3270.AIDPF5,
+		},
+		mainmenuError, // name of field to put error messages in
+		23, 79,        // cursor coordinates
+		conn)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	switch resp.AID {
+	case go3270.AIDPF1:
+		// Display help, then return to this transaction
+		return help(sess.exampleFeature), data, nil
+	case go3270.AIDPF3:
+		// Exit
+		return sess.mainmenu, nil, nil
+	case go3270.AIDPF5:
+		// Refresh
+		return sess.exampleFeature, data, nil
+	}
+
+	// ...there shouldn't be any actions not handled above. Just in case,
+	// we'll just re-run this transaction as if refresh was hit.
+	return sess.exampleFeature, data, nil
+}