Vision

Check out the following ASP.NET example for listing contact of a gmail account and adding a new contact to it. First download the Google Data API from the specified link and install it

http://code.google.com/p/google-gdata/

Then create a new project and include following references in it

Google.GData.Client.dll
Google.GData.Contacts.dll
Google.GData.Extensions.dll

Then i created the following class
using System;
using System.Collections.Generic;
using Google.GData.Contacts;
using Google.GData.Extensions;

///
/// Summary description for GoogleContactService
///
public class GoogleContactService
{
public static ContactsService GContactService = null;

public static void InitializeService(string username,
string password)
{
GContactService = new ContactsService(“Contact Infomation”);
GContactService.setUserCredentials(username, password);
}

public static List<ContactDetail> GetAllContact()
{
List<ContactDetail> contactDetails = new List<ContactDetail>();
ContactsQuery query = new ContactsQuery(ContactsQuery.
CreateContactsUri(“default”));

ContactsFeed feed = GContactService.Query(query);
foreach (ContactEntry entry in feed.Entries)
{
ContactDetail contact = new
ContactDetail{Name = entry.Title.Text,
EmailAddress1 = entry.Emails.Count >= 1 ? entry.Emails[0].Address : “”,
EmailAddress2 = entry.Emails.Count >= 2 ? entry.Emails[1].Address : “”,
Phone = entry.Phonenumbers.Count >= 1 ? entry.Phonenumbers[0].Value : “”,
Address =  entry.PostalAddresses.Count >= 1 ? entry.PostalAddresses[0].Value : “”,
Details = entry.Content.Content};

contactDetails.Add(contact);
}

return contactDetails;
}

public static void AddContact(ContactDetail contact)
{
ContactEntry newEntry = new ContactEntry();
newEntry.Title.Text = contact.Name;

EMail primaryEmail = new EMail(contact.EmailAddress1);
primaryEmail.Primary = true;
primaryEmail.Rel = ContactsRelationships.IsWork;
newEntry.Emails.Add(primaryEmail);

EMail secondaryEmail = new EMail(contact.EmailAddress2);
secondaryEmail.Rel = ContactsRelationships.IsHome;
newEntry.Emails.Add(secondaryEmail);

PhoneNumber phoneNumber = new PhoneNumber(contact.Phone);
phoneNumber.Primary = true;
phoneNumber.Rel = ContactsRelationships.IsMobile;
newEntry.Phonenumbers.Add(phoneNumber);

PostalAddress postalAddress = new PostalAddress();
postalAddress.Value = contact.Address;
postalAddress.Primary = true;
postalAddress.Rel = ContactsRelationships.IsHome;
newEntry.PostalAddresses.Add(postalAddress);

newEntry.Content.Content = contact.Details;

Uri feedUri = new Uri(ContactsQuery.CreateContactsUri(“default”));

ContactEntry createdEntry = (ContactEntry)GContactService.Insert(feedUri, newEntry);
}
}

public class ContactDetail
{
public string Name { get; set; }
public string EmailAddress1 { get; set; }
public string EmailAddress2 { get; set; }
public string Phone { get; set; }
public string Address { get; set; }
public string Details { get; set; }
}