public abstract class MonitoredSecurityTokenService : idfx.SecurityTokenService
{
    public MonitoredSecurityTokenService(SecurityTokenServiceConfiguration configuration)
        : base(configuration)
    { }

    protected virtual void OnRst(XElement rst) { }
    protected virtual void OnRstr(XElement rstr) { }
    protected virtual void OnIssuedToken(XElement issuedToken) { }

    protected override RequestSecurityTokenResponse GetResponse(RequestSecurityToken request, SecurityTokenDescriptor tokenDescriptor)
    {
        var response = base.GetResponse(request, tokenDescriptor);

        // see if token is an EncryptedSecurityToken ...
        EncryptedSecurityToken est = tokenDescriptor.Token as EncryptedSecurityToken;
        SecurityToken st;

        if (est != null)
        {
            // if so, use inner token
            st = est.Token;
        }
        else
        {
            // if not, use the token directly
            st = tokenDescriptor.Token;
        }

        SecurityTokenSerializer ser = new SecurityTokenSerializerAdapter(
            this.SecurityTokenServiceConfiguration.SecurityTokenHandlers);

        XElement token = new XElement("IssuedToken");
        XmlWriter xw = token.CreateWriter();
        ser.WriteToken(xw, st);
        xw.Close();

        try
        {
            // do monitoring callbacks
            OnRst(XElement.Parse(SerializeRequest(request)));
            OnRstr(XElement.Parse(SerializeResponse(response)));
            OnIssuedToken(token);
        }
        catch
        { }

        return response;
    }

    private string SerializeRequest(RequestSecurityToken request)
    {
        var serializer = new WSTrust13RequestSerializer();
        WSTrustSerializationContext context = new WSTrustSerializationContext();
        StringBuilder sb = new StringBuilder();
        using (var writer = new XmlTextWriter(new StringWriter(sb)))
        {
            serializer.WriteXml(request, writer, context);
            return sb.ToString();
        }
    }

    private string SerializeResponse(RequestSecurityTokenResponse response)
    {
        var serializer = new WSTrust13ResponseSerializer();
        WSTrustSerializationContext context = new WSTrustSerializationContext();
        StringBuilder sb = new StringBuilder();
        using (var writer = new XmlTextWriter(new StringWriter(sb)))
        {
            serializer.WriteXml(response, writer, context);
            return sb.ToString();
        }
    }
}