Add Update Delete SiteMap Role Attribute programmatically in ASP.Net using C#

I have created a simple sample, where the roles for a Menu in SiteMap is updated using XmlDocument.

SiteMap before update

<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0">
  <siteMapNode url="" title="Home" description="" roles="*">
    <siteMapNode url="~/Home.aspx" title="Home" description="Home Page" roles="*" />
    <siteMapNode url="javascript:;" title="Admin" description="Admin Page" roles="Administrator">
      <siteMapNode url="~/Admin/Users.aspx" title="Users" description="Users Page">
      </siteMapNode>
      <siteMapNode url="~/Admin/Reports.aspx" title="Reports" description="Reports Page">
      </siteMapNode>
    </siteMapNode>
    <siteMapNode url="~/Contact.aspx" title="Contact" description="Contact Us Page" roles="*" />
  </siteMapNode>
</siteMap>

Namespaces

using System.Xml;

Code

protected void Page_Load(object sender, EventArgs e)
{
    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.Load(Server.MapPath("~/Web.sitemap"));
    XmlNodeList elementList = xmlDoc.GetElementsByTagName("siteMapNode");
    foreach (XmlNode node in elementList)
    {
        if (node.Attributes["description"].Value == "Admin Page")
        {
            if (node.Attributes["roles"] == null)
            {
                //Create Attribute.
                XmlAttribute roles = xmlDoc.CreateAttribute("roles");
                node.Attributes.Append(roles);
            }
            //Set roles value here
            node.Attributes["roles"].Value = "Administrator,User";
        }
    }
    xmlDoc.Save(Server.MapPath("~/Web.sitemap"));
}

SiteMap after update

<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0">
  <siteMapNode url="" title="Home" description="" roles="*">
    <siteMapNode url="~/Home.aspx" title="Home" description="Home Page" roles="*" />
    <siteMapNode url="javascript:;" title="Admin" description="Admin Page" roles="Administrator,User">
      <siteMapNode url="~/Admin/Users.aspx" title="Users" description="Users Page">
      </siteMapNode>
      <siteMapNode url="~/Admin/Reports.aspx" title="Reports" description="Reports Page">
      </siteMapNode>
    </siteMapNode>
    <siteMapNode url="~/Contact.aspx" title="Contact" description="Contact Us Page" roles="*" />
  </siteMapNode>
</siteMap>