Twitter Reply EMailer

My addiction to Twitter has grown exponentially over the last month or so. I've gone from "I just don't get it" to developing a Windows Mobile application - Quakk - so I can check my Tweets on the go.

Twitter does me the favour of sending an email when when I receive a direct message, but doesn't bother when I recieve a reply - I'd prefer it the other way around. After browsing the list of available applications at the Twitter Fan Wiki I tried a few online services that claimed to monitor your replies and send notification emails, but was satisfied by none of them. The first one I tried wouldn't let me sign up due to database connection problems, and the second one sent my notifications sporadically. So I decided I could easily write my own monitor using the parts I've already developed for Quakk.

I've made the entire code for this project available to download at the bottom of this article, but if you're not a coder and you just want a copy of the application to use yourself, then that is available for download below too.

There are four classes from Quakk I'll be using: Configuration, TwitterApi, ReplyTimeline and Tweet. I've stripped out any code that's irrelevant to this project and detailed the public interfaces of these classes below, with the main code for the project below that. Please keep in mind that Quakk is still in the beta stage, so some of this code is a bit scruffy.

Configuration

public class Configuration
{
    public string LastID
    public string Username
    public string Password
    public string EmailAddress
    public string SmtpServer
    public static Configuration LoadConfiguration()
    public void Save()
}

The Configuration class deals with loading and saving your Twitter login credentials, email details and the ID of the last received tweet to an xml file. The static method LoadConfiguration() loads and parses the Xml file and returns an instance of the Configuration class populated with the details from the Xml file. These are made available as public properties, and a Save() method enables you to save any changes you make back to the Xml file.

TwitterApi

public class TwitterApi
{
    public string Username
    public string Password
    public string GetXml(string url)
}

The TwitterApi class takes care of connecting to Twitter, authenticating your user details and returning the response as a string. Create an instance of the TwitterApi, populate the Username and Password properties from your Configuration object and then call GetXml() on the desired url from the Twitter API.

Tweet

public class Tweet
{
    public string ID
    public string DisplayName
    public DateTime TweetDateTime
    public string Message
    public Tweet(XmlNode tweetXml)
}

The Tweet class takes an XmlNode as part of its constuctor which it parses and populates the public Properties from the data provided.

ReplyTimeline

public class ReplyTimeline
{
    public List<Tweet> Tweets
    protected ReplyTimeline(TwitterApi twitterApi)
    public void Update()
}

You pass in an instance of the TwitterApi to the ReplyTimeline class when you instantiate it which gives the ReplyTimeline the ability to connect to Twitter. When you call the Update method, it obtains the Xml for the 20 most recent replies from your Twitter account, parses it and creates a List of parsed Tweet objects which it makes available from its public Tweets property.

Putting it all Together

As you can see, by making use of these objects you can get a collection of Tweets live from Twitter in very little code.

// Load Configuration from Xml file, quitting if it doesn't exist
Configuration config = Configuration.LoadConfiguration();
if(config == null) return;

TwitterApi twitter = new TwitterApi
                         {
                             Username = config.Username,
                             Password = config.Password
                         };

// Update the Reply Timeline
ReplyTimeline timeline;
try
{
    timeline = new Timeline(twitter);
    timeline.Update();
}
catch(TwitterException)
{
    // We could implement some sort of logging here,
    // but since Twitter is down more than it's up 
    // I've opted to just quit the application here
    return;
}

List<Tweet> tweets = timeline.Tweets;

At this point we have a generic List of Tweet objects from our Reply Timeline.

string emailBody = "";

// Iterate through each tweet returned from the timeline 
// until we hit a tweet we've already seen
foreach(Tweet tweet in tweets)
{
    if(tweet.ID == config.LastID)
    {
        break;
    }

    // Append the current tweet's details to our email body
    emailBody += tweet.DisplayName + " replied:\r\n" +
                 tweet.Message + "\r\n\r\nAt: " +
                 tweet.TweetDateTime + "\r\n\r\n";
}

We iterate through the Tweet list building up an email containing the tweets we haven't seen yet.

// If we have tweet notifications to send then compose the email
if(emailBody != "")
{

    MailMessage mail = new MailMessage(config.EmailAddress,
                                       config.EmailAddress,
                                       "New Reply Tweet", 
                                       emailBody);

    // Send the email using the SMTP server specified in the config
    try
    {
        SmtpClient client = new SmtpClient(config.SmtpServer);
        client.Send(mail);
    }
    catch(SmtpException)
    {
        return;
    }

    // Update the ID of the last tweet in the config so we
    // can identify if we've already seen it next time
    config.LastID = tweets[0].ID;
    config.Save();
}

Then we send out the email using the details from the config file, and update the config file with the ID of the last tweet.

You also need the following Configuration.xml file in the same directory as the application.

<?xml version="1.0"?>
<Configuration>
  <LastID></LastID>
  <Username>Your Twitter Username</Username>
  <Password>Your Twitter Password</Password>
  <EmailAddress>billy@billy.com</EmailAddress>
  <SmtpServer>smtp.mysmtpserver.com</SmtpServer>
</Configuration>

How to use the Software

You can download the source in a VS2008 project, or if you're only interested in the application itself then download the app.

The application simply connects to Twitter, downloads your Replies, compiles an email of any new Replies and sends that email to you. In order to make use of it you should set it up as a scheduled task in Windows.

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