Office 365

To access to Microsoft Exchange Online as part of Microsoft Office 365, you have to find EWS url that your application will use (EWS url is first parameter in the Service constructor). In order to discover the url use AutodiscoverService class from namespace Independentsoft.Exchange.Autodiscover. When you know EWS url you can use it in the Service class and do not need to query always autodiscover service to find the url. It is enough for example to query it only first time when you start your application or periodicly check to be sure that you use valid url.

C# example

using System;
using System.Net;
using Independentsoft.Exchange;
using Independentsoft.Exchange.Autodiscover;

namespace Sample
{
    class Program
    {
        static void Main(string[] args)
        {
            NetworkCredential credential = new NetworkCredential("test@independentsoft.onmicrosoft.com", "password");
            AutodiscoverService autodiscoverService = new AutodiscoverService("https://autodiscover-s.outlook.com/Autodiscover/Autodiscover.xml", credential);

            try
            {
                UserSettingNameCollection settingNames = new UserSettingNameCollection();
                settingNames.Add(UserSettingName.ExternalEwsUrl);

                GetUserSettingsResponse response = autodiscoverService.GetUserSettings("test@independentsoft.onmicrosoft.com", settingNames);

                if (response.UserResponses.Count > 0)
                {
                    UserResponse userResponse = response.UserResponses[0];

                    UserSetting externalEwsUrlUserSetting = userResponse.UserSettings[UserSettingName.ExternalEwsUrl];

                    if (externalEwsUrlUserSetting != null)
                    {
                        Console.WriteLine("ExternalEwsUrl=" + externalEwsUrlUserSetting.Value);

                        Service service = new Service(externalEwsUrlUserSetting.Value, credential);

                        Appointment appointment = new Appointment();
                        appointment.Subject = "Test";
                        appointment.Body = new Body("Body text.");
                        appointment.StartTime = DateTime.Today.AddHours(15);
                        appointment.EndTime = DateTime.Today.AddHours(16);
                        appointment.Location = "My Office";
                        appointment.ReminderIsSet = true;
                        appointment.ReminderMinutesBeforeStart = 30;

                        ItemId itemId = service.CreateItem(appointment);
                    }
                }

                Console.Read();
            }
            catch (ServiceRequestException ex)
            {
                Console.WriteLine("Error: " + ex.Message);
                Console.WriteLine("Error: " + ex.XmlMessage);
                Console.Read();
            }
            catch (WebException ex)
            {
                Console.WriteLine("Error: " + ex.Message);
                Console.Read();
            }
        }
    }
}

VB example

Imports System.Net
Imports Independentsoft.Exchange
Imports Independentsoft.Exchange.Autodiscover

Namespace Sample
    Class Module1
        Shared Sub Main(ByVal args As String())

            Dim credential As New NetworkCredential("test@independentsoft.onmicrosoft.com", "password")
            Dim autodiscoverService As New AutodiscoverService("https://autodiscover-s.outlook.com/Autodiscover/Autodiscover.xml", credential)

            Try
                Dim settingNames As New UserSettingNameCollection()
                settingNames.Add(UserSettingName.ExternalEwsUrl)

                Dim response As GetUserSettingsResponse = autodiscoverService.GetUserSettings("test@independentsoft.onmicrosoft.com", settingNames)

                If response.UserResponses.Count > 0 Then
                    Dim userResponse As UserResponse = response.UserResponses(0)

                    Dim externalEwsUrlUserSetting As UserSetting = userResponse.UserSettings(UserSettingName.ExternalEwsUrl)

                    If externalEwsUrlUserSetting IsNot Nothing Then

                        Console.WriteLine("ExternalEwsUrl=" + externalEwsUrlUserSetting.Value)

                        Dim service As New Service(externalEwsUrlUserSetting.Value, credential)

                        Dim appointment As New Appointment()
                        appointment.Subject = "Test"
                        appointment.Body = New Body("Body text.")
                        appointment.StartTime = DateTime.Today.AddHours(15)
                        appointment.EndTime = DateTime.Today.AddHours(16)
                        appointment.Location = "My Office"
                        appointment.ReminderIsSet = True
                        appointment.ReminderMinutesBeforeStart = 30

                        Dim itemId As ItemId = service.CreateItem(appointment)

                    End If
                End If

                Console.Read()
            Catch ex As ServiceRequestException
                Console.WriteLine("Error: " + ex.Message)
                Console.WriteLine("Error: " + ex.XmlMessage)
                Console.Read()
            Catch ex As WebException
                Console.WriteLine("Error: " & ex.Message)
                Console.Read()
            End Try
        End Sub
    End Class
End Namespace