RSS Technical Article

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Introduction

This document details the RSS Features, usage and Critical Fix designed and Developed by 'Sankha Biswas' and 'Srinivasa Rao Ayyla Somayajula' from Wipro Technologies.

RSS Feed Duplication Problem in Outlook 2007

Whenever a RSS Feed is getting subscribed into Outlook 2007, it starts duplicating RSS Feed Items. It is a critical issue and most of the RSS Newsreaders are facing this problem. This is not observed in IE7.

Resolution/Hot Fix we developed

Ideally each RSS Feed item must have a unique Guid and Link value, otherwise Outlook 2007 will consider it as a new feed item and will start duplicating them.

We have fixed the issue by generating unique Guid and Link value for each RSS Feed Item by hashing RSS Entry Description into corresponding Hash string (hexadecimal) and using it in Guid and Link value. And as a result the problem with "RSS Feed Duplication" in Outlook 2007 has been resolved. We kept examing the fix for one week, in different machines running under different OS's and found no more duplicate feeds.

Using the code

The fix can be used world wide for any kind of RSS implementation.
A generic Class called "RSSBuilder" will take care of generating RSS Feed Items.

Hashing algorithm we developed

/// <summary>
/// Getting the Hash of the Description to generate unique Guid
/// and Link entry for each RSS Feed Item.
/// This function Fixed the Critical Issue with RSS Feed Duplication
/// in MICROSOFT OUTLOOK 2007
/// Developed By: 'Sankha Biswas' and 'Srinivasa Rao Ayyla Somayajula'
/// from Wipro Technologies
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
static public string GetMd5Hash(string strDesc)
{
// Converting the string into bytes
Encoder enc = System.Text.Encoding.Unicode.GetEncoder();

// Create a buffer large enough to hold the string
byte[] unicodeText = new byte[strDesc.Length * 2];
enc.GetBytes(strDesc.ToCharArray(), 0, strDesc.Length, unicodeText, 0, true);

// Hashing...
MD5 md5 = new MD5CryptoServiceProvider();
byte[] result = md5.ComputeHash(unicodeText);

// Building the final string by converting each byte
// into hex and appending it to a StringBuilder
StringBuilder sb = new StringBuilder();
for (int i = 0; i < result.Length; i++)
{
sb.Append(result[i].ToString("X2"));
}

// returning the hash string
return sb.ToString();
}

History

We have fixed the issue with RSS Feed Duplication in OUTLOOK 2007 by generating unique Guid and Link value for each RSS Feed Item by hashing RSS Entry Description into corresponding Hash string (hexadecimal) and using it in Guid and Link value. And as a result the problem with "RSS Feed Duplication" in Outlook 2007 has been resolved. Now it's perfectly showing unique feed Items...:)