Getting a Twitter interface on your site

If you are using Twitter, you may want to mashup your tweets into your web application. You may even want to give your site admin (you!) the facility to update your Twitter status from within your application.

Fortunately, the Twitter API uses a straightforward interface which is easily manipulated from an ASP.NET application. Full details of the Twitter API are available from the Twitter API Wiki.

Getting your Twitter status into your ASP.NET application

The Twitter function calls use REST to allow a flexible mechanism for accessing indformation. Information can be retrieved in several format, but for our purposes the simplest formats are as an RSS formatted XML file or a plain XML file. The RSS format provides a simplified format for the information, but the XML format provides complete information about a user and their updates.

The simplest method is to call the Twitter user_timeline function. You can call the function by requesting the information in either XML or RSS format. The format for the call is:

for a public Twitter feed, or:

for a private Twitter feed, though the private mechanism requires user authentication.

Note: .type is replaced by either .rss or .xml, depending on the format you want to get back.

The choice of RSS or XML depends on the level of information which you want back from Twitter. The XML format provides more detail, but in either case it is simply a matter of retrieving the response from the request and extracting the relevant information from the XML tags which are returned.

Getting information from the RSS request

The first requirement is to make use of the WebClient class, optionally provide authentication (if your tweets are not public), request the status using the URL from above, and then unpack the reply, placing it into a suitable format within your web page. The basic code for extracting status reports from the RSS request and dropping them into a <dl> element is shown below:

WebClient twitter = new WebClient();
twitter.Credentials = // only needed for non-public tweets
   new NetworkCredential("userid", "password");
Stream tweets = twitter.OpenRead
XmlDocument mytweets = new XmlDocument();
litTweets.Text = "\n<dl>\n";
foreach (XmlNode status in mytweets.GetElementsByTagName("item"))
  DateTime tim = Convert.ToDateTime
  string text = status.SelectSingleNode("description").InnerText;
  text = text.Substring(text.IndexOf(":")+ 2);
  litTweets.Text += string.Format
    ("  <dt>{0:D} {0:t}</dt>\n  <dd>{1}</dd>\n", tim, text);
litTweets.Text += "</dl>\n";

Note how the pubDate element from the RSS feed is converted back to a DateTime object so that it can be processed. If you want to display the time using Twitter's conventional relative time format you can use the DateTime methods to calculate the offset from the current time. For example:

WebClient twitter = new WebClient();
Stream tweets =
XmlDocument mytweets = new XmlDocument();
litTweets.Text = "\n      <dl>\n";
foreach (XmlNode status in mytweets.GetElementsByTagName("item"))
  DateTime pubDate =
  long ticks = DateTime.UtcNow.Ticks - pubDate.Ticks;
  TimeSpan elapsed = new TimeSpan(ticks);
  string tim;
  if (elapsed.Days > 1)
    tim = string.Format("about {0} days ago", elapsed.Days);
  else if (elapsed.Days > 0)
    tim = "about a day ago";
  else if (elapsed.Hours > 1)
    tim = string.Format("about {0} hours ago", elapsed.Hours);
  else if (elapsed.Hours > 0)
    tim = "about an hour ago";
  else if (elapsed.Minutes > 1)
    tim = string.Format
                     ("about {0} minutes ago", elapsed.Minutes);
  else if (elapsed.Minutes > 0)
    tim = "about 1 minute ago";
  else if (elapsed.Seconds > 10)
    tim = string.Format
                     ("about {0} seconds ago", elapsed.Seconds);
  else tim = "within the last 10 seconds";
  string text = status.SelectSingleNode("description").InnerText;
  text = text.Substring(text.IndexOf(":") + 2);
  litTweets.Text += string.Format
    ("        <dt>{0}</dt>\n        <dd>{1}</dd>\n", tim, text);
litTweets.Text += "      </dl>\n"; 

Check out a demonstration of this code.

Getting information from the XML request

The advantage of the XML request is that the response from Twitter provides a complete status record for each of the users updates, whereas the RSS request only returns basic information. So the XML request allows you to include more information about each update, including such thins as the origin of the update and a link to the user's photo.

However, the main stumbling block is that the date/time format used in the XML response doesn't get recognised by the ASP.NET Convert.ToDateTime method. This means you have to do a bit of work to extract the Date Time from the response. This is the date time format returned by the RSS response:

Fri, 06 Mar 2009 15:26:40 +0000

This is what is returned by the XML response:

Fri Mar 06 15:26:40 +0000 2009

It is a simple matter to convert the XML date format to match the RSS date format. e.g.

protected DateTime CreatedAt(string raw)
  string rssText = raw.Substring(8, 3) // Day
                 + raw.Substring(4, 4) // Month
                 + raw.Substring(26, 4) // Year
                 + raw.Substring(10, 15); // Time & offset
  return Convert.ToDateTime(rssText);

The demonstration page shows use of the following elements from the XML response:

  • created_at - the time of the update
  • user/name - the full name of the user
  • text - the text of the update
  • user/profile_image_url - a URL to the users profile image
  • source - the source of the update (web or txt)

Check out a demonstration of this code.

Updating your status on Twitter

The Twitter API allows you to POST updates from your applications, however, it would be unwise to provide a generic update page for any user to to use to post their updates unless you can demonstrate that your site is trusted. After all, your application would be handling usernames and passwords for end users. This mini-tutorial will show how you can provide an admin only page (secured by some user authentication on the site of course) which will allow you to update your (or your site's) status on Twitter.

We can use the same mechanism to generate a WebClient call to the Twitter API, but in this case you must make sure the call uses POST to pass the update string, and of course the call requires authentication with Twitter. You just need a TextBox to hold your status message, and a button to call the update code. The code is very straightforward:

               = false; // Fixes problem with Twitter POST calls
WebClient twitter = new WebClient();
          ("Content-Type", "application/x-www-form-urlencoded");
twitter.Credentials =
                 new NetworkCredential("twitterid", "password");
byte[] response = twitter.UploadData
            Encoding.UTF8.GetBytes("status=" + TextBox1.Text));

At this point the response is in a byte array. If you want to use the response to provide feedback from the call you can convert the byte array into a string using the call:

XmlDocument responseXML = new XmlDocument();

At this point you are free to parse the results and display them on your page.

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