Getting Started with SharePoint Online Development

Authenticating against SharePoint Online

The first place I would start is here to learn how to authenticate against SharePoint Online (O365). This will give you a good understand of what libraries are available to do the claims based authentication SharePoint Online uses. It also explains it in an easy to understand manner. Remote Authentication in SharePoint Online Using Claims-Based Authentication – This is a article, but really what you want is the code / solution you can use to connect to your SharePoint Online site and get its title. Here is the direct link to download the solution for Visual Studio. You can also check out this library instead. They both do similar authentication. These libraries are great because they make authenticating against SharePoint Online which is a MAJOR pain in the rear, much easier.

If you are doing your development on a machine that does not have SharePoint 2010 installed you will need the SharePoint Foundation 2010 Client Object Model Redistributable. This gives you among other things the Microsoft.SharePoint.Client.dll and Microsoft.SharePoint.Client.Runtime.dll assemblies which you will need. If you have an installation of SharePoint 2010 on another machine you can copy these files from the c:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\ISAPI directory. If you have trouble, you may want to look here first for a code tweak that brings up the login screen. I did not find it necessary to do the tweak, but some people do.

As it turns out the SharePoint Online requires a bit more work to get the authentication to work than the standard example for SharePoint 2010 show. This is because SharePoint Online uses Claims-Based Authentication. For whatever reason it is not implemented and certainly is not transparent in the SharePoint Client Object Model. What I recommend is downloading the solution from above if you have not already done so since this has the Claims-Based Authentication implemented for you. You should still be able to use most samples for SharePoint 2010 regarding the CSOM (SharePoint Client Object Model), but you will need to do two things to make them work (which is related to authentication).

1. Add a reference to the ClaimsAuth (that is from the solution above).
2. In the code replace any calls to new ClientContext(url) with ClaimClientContext.GetAuthenticatedContext(url);

Once you are authenticated, the api should be the same.

Technology Overview

The SharePoint Foundation provides an api to interact with SharePoint (both SharePoint 2010 and SharePoint Online) data remotely from script that executes in the browser, Silverlight, or .NET applications. The api includes a subset of the features available in the SharePoint Object Model (Microsoft.SharePoint.dll) that you would use if you were running your code on the SharePoint Server itself (which is not an option if you are using Microsoft SharePoint Online). Each language uses the same api to make switching between them easier. Obviously, the syntax is different for each language.

Microsoft decided to make the client object model instead of constantly trying to extend the web services. The reason is that with the client object model it is very similar to the server object model that was available on the SharePoint server itself. This makes providing new features much easier and also easier for developers since there is one object model needed for both client and server (in many cases).

You can do most things you can do with the server object model. The following areas are supported by the client object model:

• Site Collections and Sites
• Lists, List Items, Views, and List Schemas
• Files and Folders
• Web, List, and List Item Property Bags
• Web Parts
• Security
• Content Types
• Site Templates and Site Collection Operations

This has some advantages over the web services that Microsoft used to require developers to use. The biggest advantage may be that it does not have the overhead associated with web services (xml bloat).

A good resource is the Client Object Model Resource Center.

A great video to get more details.

IMPORTANT: It only works with .NET 3.5 right now. It does NOT work with a .NET 4.0 project.

Do your first project.

1. Create a new .NET Command Line application (or other type if you prefer) using the 3.5 (4.0 is the default and will not work as of 2012-07-26)
2. Make sure you compiled the ClaimsAuth project that is located in the Remote Authentication in SharePoint Online Using the Client Object Model solution and reference the ClaimsAuth.dll, or just add that project to your project if you prefer to have the source code.
3. Add a reference to the Microsoft.SharePoint.Client.dll and Microsoft.SharePoint.Client.Runtime.dll to your project as well. Remember, you can get that from SharePoint Foundation 2010 Client Object Model Redistributable installation or from c:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\ISAPI on an existing SharePoint 2010 installation.
4. Add [STAThread] attribute to the Main method.
5. Make your Main method look like this (you’ll need to change the url)
   [STAThread]
   static void Main(string[] args)
   {
       using (ClientContext clientContext = ClaimClientContext.GetAuthenticatedContext(https://yoursite.sharepoint.com/teams/site1/site2/etc))
       {
           Web site = clientContext.Web;
           clientContext.Load(site); // tell model we want that data
           clientContext.ExecuteQuery(); // actually go to SharePoint and get data
           Console.WriteLine("Title: {0}", site.Title);
       }
   }
6. I have highlighted the most important pieces that are different from what you would do in SharePoint 2010. When you run it you will see a browser object popup and then continue. That is all there is to it.

Where to go from here

Using the SharePoint Foundation 2010 Managed Client Object Model – good tutorial that covers lots of the CRUD type operations you may need to do.

You may prefer to use LINQ instead of CAML to do your queries. This may be a good place to start.