For example, CodeDigest Rss feed will look like,

<?xml version="1.0" encoding="utf-8" ?>

<rss version="2.0">

  <channel>

  <title>CodeDigest.com Latest Articles</title>

  <link>http://www.codedigest.com</link>

  <description>Latest articles hosted on CodeDigest.com.</description>

  <item>

  <title>Useful Datagrid Tips</title>

  <description>There are some frequent queries that are being asked in most of the forums and UG’s regarding datagrid. I have compiled a list of useful tips from my previous posts and posted it here.</description>

  <link>http://www.codedigest.com/Articles/ASPNET/77_Useful_Datagrid_Tips.aspx</link>

  <pubDate>4/29/2008 9:47:12 AM</pubDate>

  </item>

</channel>

  </rss>

As we can see the above XML, the whole contents are packed inside <rss> tag. The actual information about the posts is kept inside <item> tag which in turn is packed inside a <channel> tag. Read the history and specification of RSS here. Moving forward this article will help us understand constructing an RSS feeds for our asp.net sites.

What we need to do?

Generating RSS feed for our website is nothing but emitting the frequently updated data in the above specified XML format. It can be done by constructing the XML document and performing a Response.Write of the constructed XML document.

What should we use?

Our requirement can be achieved by performing a Response.Write on an ASPX page. But, in this article we will generate our RSS feed using HttpHandler instead of an ASPX page. There are some advantages in using HttpHandler over an ASPX pages, an ASPX page will have a series of events like OnInit, Page load, etc  which is not at all required in our case. These page level events are over head since we just want to get the data from database and construct a XML document and output the raw xml.

Implementation

With the RSS feed XML format in mind, we can construct XML using XmlTextWriter class. Include an HttpHandler to our project by right clicking solution and clicking “Add New Item”. Refer the below figure.

RSS.ashx

<%@ WebHandler Language="C#" Class="Rss" %>

using System;

using System.Web;

using System.Data;

using System.Text;

using System.Xml;

using DataAccess;

public class Rss : IHttpHandler {

    ArticleDAO articleDAO = new ArticleDAO();

    public void ProcessRequest (HttpContext context) {

        // Clear any previous output from the buffer

        context.Response.Clear();

        context.Response.ContentType = "text/xml";

        XmlTextWriter cdRSS = new XmlTextWriter(context.Response.OutputStream, Encoding.UTF8);

        cdRSS.WriteStartDocument();      

        cdRSS.WriteStartElement("rss");

        cdRSS.WriteAttributeString("version", "2.0");       

        cdRSS.WriteStartElement("channel");

        cdRSS.WriteElementString("title", "CodeDigest.com Latest Articles");

        cdRSS.WriteElementString("link", "http://www.codedigest.com");

        cdRSS.WriteElementString("description", "Latest articles hosted on CodeDigest.com.");

        cdRSS.WriteElementString("copyright", "Copyright 2008 - 2009 CodeDigest.com. All rights reserved.");

       //Connect database to get the data

        DataTable dtArticles = articleDAO.GetArticlesForRss();

        for (int i = 0; i < dtArticles.Rows.Count; i++)

        {

       //Build Item tags with the data from database

            cdRSS.WriteStartElement("item");

            cdRSS.WriteElementString("title", dtArticles.Rows[i]["Title"].ToString());

            cdRSS.WriteElementString("description", dtArticles.Rows[i]["description"].ToString());

            cdRSS.WriteElementString("link", "http://"+ context.Request.Url.Host + dtArticles.Rows[i]["URL"].ToString());

            cdRSS.WriteElementString("pubDate", dtArticles.Rows[i]["ApprovedOn"].ToString());

            cdRSS.WriteEndElement();

        }

        cdRSS.WriteEndElement();

        cdRSS.WriteEndElement();

        cdRSS.WriteEndDocument();

        cdRSS.Flush();

        cdRSS.Close();

        context.Response.End();     

    }

    public bool IsReusable {

        get {

            return false;

        }

    }

}

You can read more about HttpHandler from the articles in the reference section.