Using the Web Application version number from an assembly (ASP.NET/C#)

To add to the responders that have already posted. In order to get the assembly version in an ASP.Net web application you need to place a method in the code behind file similar to:

protected string GetApplicationVersion() {
    return System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
}

In the ASPX page you want to display the version number simply place:

<%= GetApplicationVersion() %>

Version version = new Version(Application.ProductVersion);
string message = version.ToString();

Some info here: http://www.velocityreviews.com/forums/showpost.php?p=487050&postcount=8

in asp.net 2.0 each page is built into it own assembly, so only the dll the AssemblyInfo.cs is built into will return the correct answer. just add a static method to AssemblyInfo.cs that returns the version info, and call this method from your other pages.

-- bruce (sqlwork.com)

But I wrote a simple method to do that:

    public static string GetSystemVersion(HttpServerUtility server)
    {
        System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
        doc.Load(server.MapPath("~/web.config"));
        System.Xml.XmlNamespaceManager ns = new System.Xml.XmlNamespaceManager(doc.NameTable);
        ns.AddNamespace("bla", "http://schemas.microsoft.com/.NetConfiguration/v2.0");

        System.Xml.XmlNode node = doc.SelectSingleNode("/bla:configuration/bla:system.web/bla:authentication/bla:forms[@name]", ns);

        string projectName = "";
        if (node != null && node.Attributes != null && node.Attributes.GetNamedItem("name") != null)
            projectName = node.Attributes.GetNamedItem("name").Value; //in my case, that value is identical to the project name (projetname.dll)
        else
            return "";

        Assembly assembly = Assembly.Load(projectName);
        return assembly.GetName().Version.ToString();
    }

The question states with no reference (instances) it did not (originally) say with no knowledge of web application types.

EDIT the OP clarified to state that yes they do really require no knowledge of types within the calling web assembly, so the answer is appropriate. However I would seriously consider refactoring such a solution such that the version is passed into the other assembly.

For most people in this scenario if you know the custom HttpApplication type:

 typeof(MyHttpApplication).Assembly.GetName().Version

and if you only have a dynamic generated type:

 typeof(DynamiclyGeneratedTypeFromWebApp).BaseType.Assembly.GetName().Version

Stop voting me down for this answer :)