Google + OAuth and/or DotNetOpenAuth to get a contact list - VB.net

Question

I'm probably missing something incredibly obvious here, so that's why I'm asking my question...in the hope that someone can see what I'm missing. I just learned about OAuth for the first time last week, and I'm trying to use it (in this case) to extract a contact list from someone once they've logged in and authorized it.

Here's what I tried first, using the Google .NET library:

        Sub InviteGmailContactsOld()

    Call google_api.GetClientCredentials(Vars.Server_name)
    Dim Input_URL As String = google_api.Token_Request_URL & "?scope=" & OverrideEncode("https://www.google.com/m8/feeds/") & "&oauth_callback=" & OverrideEncode(Vars.Site_Root & "my-profile/manage-connections/invite-connections/google/")
    Dim Input_URI As New Uri(Input_URL)
    Dim Authenticator As OAuth3LeggedAuthenticator = New OAuth3LeggedAuthenticator("Politistream API", google_api.Client_ID, google_api.Client_Secret, String.Empty, String.Empty)
    Dim Auth_Request As WebRequest = Authenticator.CreateHttpWebRequest("GET", Input_URI)
    Dim Final_Request As WebRequest = WebRequest.Create(Input_URI)
    Dim Auth_Headers As String = Auth_Request.Headers.ToString()
    Final_Request.Headers.Add(Auth_Headers)
    Final_Request.Method = "GET"
    Response.Write(Final_Request.Headers.ToString() & " <br />" & Final_Request.RequestUri.ToString & "<br />")
    Dim Auth_Response As String = Common.WebRequestToStringResponse(Final_Request)

End Sub

Tried this in several variations, and no matter what I did, all I got back from Google was 400 Bad Request.

Then I tried DotNetOpenAuth:

        Sub InviteGmailContacts()
    ' GMail uses openID because OAuth doesn't work properly.

    Dim openId As New OpenIdRelyingParty
    Call google_api.GetClientCredentials(Vars.Server_name)
    Dim New_URL As UriBuilder = New UriBuilder(Request.Url.ToString)
    Dim Auth_Request As IAuthenticationRequest = openId.CreateRequest(google_api.OpenID_Login_URL, New_URL.Uri, New_URL.Uri)
    Auth_Request.RedirectToProvider()

End Sub

This works, and I was able to get the claimed identifier back. The problem that I have no is that I have absolutely no idea what the heck I'm supposed to do with it, and I can't find anything anywhere that I can follow along and more or less make my own.

Ideally, what I'm looking for is a code sample that isn't necessarily complete, but is at least coherent enough that I can get where I want to go. Failing that, an explanation that's dumbed down about three shades from the normal level will suffice.

Thanks.

Answer 1

You're confusing OAuth, which you use in your first code snippet with Google, with OpenID which is in your second snippet. OpenID gives you, as you noticed, a "claimed identifier" which isn't good for downloading contacts -- it's good for recognizing a user when they come back later. OpenID is for authentication whereas OAuth is for authorization .

Since you want to access Google Contacts, that's an authorization scenario so you need OAuth. DotNetOpenAuth does OAuth too, and there's a sample for downloading Contacts in fact (albeit in C#).

Download dotnetopenauth and check out the OAuthConsumerWpf sample. It has a tab that demonstrates downloading Google Contacts. It uses code in the DotNetOpenAuth.ApplicationBlock sample (the class called GoogleConsumer ) that will hopefully inspire you on what you can do in your app.