Create A Bot In .NET Using Bot Framework SDK

Thanks to the Bot Framework v4 SDK Templates, we will have all the necessary libraries and codes included in the project. We will build and run the solution.

We will see a default page in our browser after running the bot solution.

Now our bot is ready to test with endpoint URL http://localhost:3978/. However, we will explore a bit more on the code of the solution.

Let’s see startup class.

We can see some of the configuration services for the bot solution.

You can observe that a singleton scope is added for authentication with the bot Adopter. In other words, the Bot framework authentication is created that is to be used with the Bot Adopter. Similarly, a service AdapterWithErrorHandler injected for error handling. And the last service for bot implementation is transient. To summarize, we are doing the following three in service collections.

• Create the Bot Framework Authentication to be used with the Bot Adapter.
• Create the Bot Adapter with error handling enabled.
• Create the bot as a transient. In this case, the ASP Controller is expecting an IBot.

By default, bot adapter error handler class is created to handle the error related with bot authentication processes and send/receive activities from the bot connector service.

Code

public class AdapterWithErrorHandler: CloudAdapter {
    public AdapterWithErrorHandler(BotFrameworkAuthentication auth, ILogger < IBotFrameworkHttpAdapter > logger): base(auth, logger) {
        OnTurnError = async (turnContext, exception) => {
            // Log any leaked exception from the application.
            logger.LogError(exception, $ "[OnTurnError] unhandled error : {exception.Message}");
            // Send a message to the user
            await turnContext.SendActivityAsync("The bot encountered an error or bug.");
            await turnContext.SendActivityAsync("To continue to run this bot, please fix the bot source code.");
            // Send a trace activity, which will be displayed in the Bot Framework Emulator
            await turnContext.TraceActivityAsync("OnTurnError Trace", exception.Message, "https://www.botframework.com/schemas/error", "TurnError");
        };
    }
}

Additionally, you will see EchoBot.cs which is the main class for Bot activities, called as Activity Handler.

public class EchoBot: ActivityHandler {
    protected override async Task OnMessageActivityAsync(ITurnContext < IMessageActivity > turnContext, CancellationToken cancellationToken) {
        var replyText = $ "Echo: {turnContext.Activity.Text}";
        await turnContext.SendActivityAsync(MessageFactory.Text(replyText, replyText), cancellationToken);
    }
    protected override async Task OnMembersAddedAsync(IList < ChannelAccount > membersAdded, ITurnContext < IConversationUpdateActivity > turnContext, CancellationToken cancellationToken) {
        var welcomeText = "Hello and welcome!";
        foreach(var member in membersAdded) {
            if (member.Id != turnContext.Activity.Recipient.Id) {
                await turnContext.SendActivityAsync(MessageFactory.Text(welcomeText, welcomeText), cancellationToken);
            }
        }
    }
}

In the above code, OnMessageActivityAsync is the method for message activities, and OnMembersAddedAsync is for member addition.

As per the above class, the bot will echo the message you send. We will proceed with testing.

Test the bot with Bot Framework Emulator

As elucidated above, Bot Framework Emulator is an emulator through which we will connect our bot and do testing. We will open the emulator.

Once the Bot Emulator opens, it will be as shown above. To test our bot, we click create a new bot configuration as portrayed above, which will pop up another window to enter bot name, endpoint URL, and other information. However, for our bot, we need to give a bot name and endpoint URL to our bot solution. Our endpoint for bot is http://localhost:3978/ (localhost and port number) plus /api/messages is added to get complete path.

Click save and connect.

After that, we will see the below screen to test the bot.

We will send message, and bot will respond with Echo and message.

Cheers !! We have successfully tested our bot with Emulator by sending message and Bot response.

Since, this article has elaborated with getting started with bot using bot framework SDK, however, we can build complex bots using complex business cases, and integrating with AI as well.

Conclusion

In this article, I have described what a bot is, how it works, and tools required for building bots. Furthermore, I have elaborated Bot Framework SDK and develop a bot using it. We can build bots using this Bot framework SDK for any kind of scenarios from simple to complex nature and implementing additional services like AI and so on. Bot developed using Bot Framework works with the combination of Azure Bot Service. In addition to that, we have Bot Emulator to test the bot and ready-made project templates for Visual Studio which is available in Visual Studio marketplace as Bot Framework v4 SDK Templates.

References

• Microsoft