BotBuilder-Samples/Node/core-DirectLine/DirectLineBot/app.js

// This loads the environment variables from the .env file
require('dotenv-extended').load();

var builder = require('botbuilder');
var restify = require('restify');

// Setup Restify Server
var server = restify.createServer();
server.listen(process.env.port || process.env.PORT || 3978, function () {
    console.log('%s listening to %s', server.name, server.url);
});

// Create connector and listen for messages
var connector = new builder.ChatConnector({
    appId: process.env.MICROSOFT_APP_ID,
    appPassword: process.env.MICROSOFT_APP_PASSWORD
});
server.post('/api/messages', connector.listen());

var instructions = 'Welcome to the Bot to showcase the DirectLine API. Send \'Show me a hero card\' or \'Send me a BotFramework image\' to see how the DirectLine client supports custom channel data. Any other message will be echoed.';

var bot = new builder.UniversalBot(connector, function (session) {

    var reply = new builder.Message()
        .address(session.message.address);

    var text = session.message.text.toLocaleLowerCase();
    switch (text) {
        case 'show me a hero card':
            reply.text('Sample message with a HeroCard attachment')
                .addAttachment(new builder.HeroCard(session)
                    .title('Sample Hero Card')
                    .text('Displayed in the DirectLine client'));
            break;

        case 'send me a botframework image':
            reply.text('Sample message with an Image attachment')
                .addAttachment({
                    contentUrl: 'https://docs.microsoft.com/en-us/bot-framework/media/how-it-works/architecture-resize.png',
                    contentType: 'image/png',
                    name: 'BotFrameworkOverview.png'
                });

            break;

        default:
            reply.text('You said \'' + session.message.text + '\'');
            break;
    }

    session.send(reply);

});


bot.on('conversationUpdate', function (activity) {
    // when user joins conversation, send instructions
    if (activity.membersAdded) {
        activity.membersAdded.forEach(function (identity) {
            if (identity.id === activity.address.bot.id) {
                var reply = new builder.Message()
                    .address(activity.address)
                    .text(instructions);
                bot.send(reply);
            }
        });
    }
});