https://docs.microsoft.com/en-us/bot-framework/nodejs/bot-builder-nodejs-dialog-manage-conversation-flow

用dialogs 及 waterfalls等觀念，
定義好整套conversation腳本。

舉例 訂餐bot

1. 完餐點餐流程
2. 在任何時候，呼叫 ”help” 時，立刻進入其他的服務。
3. 跳過目前的流程，進入 “help” 的流程
4. 可以處理 複數的目地

var inMemoryStorage = new builder.MemoryBotStorage();

// This is a dinner reservation bot that uses a waterfall technique to prompt users for input.
var bot = new builder.UniversalBot(connector, [
    function (session) {
        session.send("Welcome to the dinner reservation.");
        builder.Prompts.time(session, "Please provide a reservation date and time (e.g.: June 6th at 5pm)");
    },
    function (session, results) {
        session.dialogData.reservationDate = builder.EntityRecognizer.resolveTime([results.response]);
        builder.Prompts.number(session, "How many people are in your party?");
    },
    function (session, results) {
        session.dialogData.partySize = results.response;
        builder.Prompts.text(session, "Whose name will this reservation be under?");
    },
    function (session, results) {
        session.dialogData.reservationName = results.response;

        // Process request and display reservation details
        session.send(`Reservation confirmed. Reservation details: <br/>Date/Time: ${session.dialogData.reservationDate} <br/>Party size: ${session.dialogData.partySize} <br/>Reservation name: ${session.dialogData.reservationName}`);
        session.endDialog();
    }
]).set('storage', inMemoryStorage); // Register in-memory storage