Where should I read my username and password for my WCF Service?

I have a WPF application that has just one button. When the button is clicked, all it does is open the service. Here is the code:

 private void button1_Click(object sender, RoutedEventArgs e)
    {
        ServiceReference1.TestServiceClient c = new ServiceReference1.TestServiceClient();

        XDocument doc = XDocument.Load(@"c:\Test\Test.xml");

        c.ClientCredentials.UserName.UserName = doc.Root.Element("Credentials").Attribute("username").Value;
        c.ClientCredentials.UserName.Password = doc.Root.Element("Credentials").Attribute("password").Value;

        try
        {
            c.Open();
        }
        catch (Exception ex)
        {

        }
    }

As you can see from above, I am reading the username and password from a Credentials node in an xml file to validate the client. Is it proper to have it located here, because originally, I had it defined in my Validate method:

 public override void Validate(string userName, string password)
    {

       // XDocument doc = XDocument.Load(@"c:\Test\Test.xml");

       // userName = doc.Root.Element("Credentials").Attribute("username").Value;
      //  password = doc.Root.Element("Credentials").Attribute("password").Value;


        if (string.IsNullOrEmpty(userName))
            throw new ArgumentNullException("userName");
        if (string.IsNullOrEmpty(password))
            throw new ArgumentNullException("password");

        // check if the user is not test
        if (userName != "test" || password != "test")
            throw new FaultException("Username and Password Failed");
    }

But the problem with the above is that whatever I pass into c.ClientCredentials.UserName.UserName and c.ClientCredentials.UserName.Password gets overriden when it reaches the Validate method. For example, in my button click, if I just have:

c.ClientCredentials.UserName.UserName = "test1";

c.ClientCredentials.UserName.Password = "test1";

The above should fail, but when it goes into the Validate method where I read the xml file that has the username and password a开发者_开发问答ttribute as test and test, it will pass.

As a side note, I noticed that my Validate method gets called, but I can't seem to step into. The debugger symbols don't get loaded.

you are overwriting the parameter with your read

 public override void Validate(string suppliedUserName, string suppliedPassword){
     // ...
     string validUserName = doc.Root.Element("Credentials").Attribute("username").Value;
     string validPassword = doc.Root.Element("Credentials").Attribute("password").Value;