SharePoint 2010: The Client Object Model

Referred URLs:

http://www.chakkaradeep.com/post/SharePoint-2010-Introducing-the-Client-Object-Model.aspx

If you want to access SharePoint Server 2007 Data today, you have two ways of doing it (based on your needs):

1. Writing a Server Application

o This application resides in server

2. Writing a Client Application

o This client application can run from any other server or a desktop

How are we building these Server and Client applications today?

Server Application

We interact with the Server Object Model, which are nothing but SharePoint APIs and build applications.

For example:

List<Announcement> announcements = new List<Announcement>();

SPSite site = SPContext.GetContext(HttpContext.Current).Site;

using (SPWeb curWeb = site.OpenWeb())

{

SPList lstAnnouncements = curWeb.Lists[new Guid(LibraryName)];

//rest of the code

}

Client Application

We use the SharePoint Web Services which then interacts with the SharePoint API. Usually, developers either build their own set of web services which exposes only certain methods/functions they want to expose to the application or consume the default out of the box SharePoint web services. This becomes difficult if you are going write rich client applications such as Silverlight, or Javascript applications and most of the time accessing SharePoint data via web services is complicated. That is why, I am not going to show you an example code!

The Future of SharePoint Client Applications

SharePoint 2010 introduces the new Client Object Model. From the sneak peak videos:

“The Client Object Model (OM) is a new programming interface for SharePoint 2010 where code runs on a user’s client machine against a local object model and interacts with data on the SharePoint Server. Client OM methods can be called from JavaScript, .NET code or Silverlight code and makes building rich client applications for SharePoint easy.”

So, how things are going to change?

One API to rule them all – Yep, whether its WPF or Windows Forms or Silverlight or Javascript – your code uses Client Object Model to interact with the SharePoint site to access the data. Now, there is something common that everybody can use instead of creating their own wrapper services to access SharePoint data!

Any code sample?

The only source of information available for now is the Developer Sneak Peak Video.

In the video, a Silverlight application is built using the Client Object Model.

The assemblies added to the project are:

• Microsoft.SharePoint.Client.Silverlight.dll
• Microsoft.SharePoint.Client.Silverlight.Runtime.dll

And also there is a using statement added in the code behind:

using Microsoft.SharePoint.Client;

And the code showcasing this new Client Object Model:

You can explore the Microsoft.SharePoint.Client namespace in the SharePoint 2010 Technical Preview Documentation

What are the different Client OM supporting in the SharePoint 2010 API? [Client API]

1. .NET Managed Client - Implemented in .NET CLR. I mean we use this in Web, Windows and Console applications.
2. Silverlight Client - You can use the SharePoint objects in Silver light coding. Wow, this is going to be a huge advantage to  the Silverlight applications which can be integrated into SharePoint. Before we don't have access to SharePoint objects inside Silverlight context.
3. ECMAScript Client - Through javascript too, we can get context and do manipulations to SharePoint objects. Do you think it's possible? Yes, its a brilliant way of thinking from Microsoft SharePoint team and this will help in great scenarios. Will explain later in this article.

Why Client Object Model comes into the picture? Are there any specialties of them?

The main started point to think by SharePoint team are as follows.

1. Is it really necessary to have SharePoint installed on server for SharePoint development? - Yes, in SharePoint 2007 you have to install SharePoint on the server to write code and test it.
2. What is the advantage of writing more web services to serve what the clients are looking for? - This is completely not a feasible solution to give or expose web services for each and every single requirement to get and manipulate data. It has plenty of limitations and if Microsoft exposes 500 web services and you didn't find what you really need and they are just waste. Instead write whatever you want and use them.
3. The great thinking and beautiful solution to the people who don't allow server side coding in the SharePoint sites is ECMAscript client OM. You can create a simple javascript file and deploy into the server to get what you needed. As we know, most of the clients don't allow server side coding but they want something to be developed. In SharePoint 2007 it's very difficult to get this job done. But now in SP 2010 very easy.

So, these things take into high priority and makes them to come up with a great solution in the form of Client Object Model. The great advantage of it is completely looks [Syntax] like the SharePoint Object Model. So, nothing new for developers and no confusion. Infact very simple to manage and write code. 

SharePoint object model syntax:

Now, I believe you have understood the Client OM concept. Now, we will discuss a little bit about technical implementation.
SharePoint 2010 provides the client support files to refer the SharePoint objects and communicate with the SharePoint server. Below are the details.

.NET Managed Deployment

Microsoft SharePoint Foundation 2010 installs Microsoft.SharePoint.Client.dll and Microsoft.SharePoint.Client.Runtime.dll in %ProgramFiles%\Common Files\Microsoft Shared\web server extensions\14\ISAPI for easy access in development. You must have both Microsoft.SharePoint.Client.dll and Microsoft.SharePoint.Client.Runtime.dll to develop a solution remotely with the .NET managed object model. For a Windows Forms, Windows Presentation Foundation (WPF), or other application that calls the .NET managed SharePoint Foundation client APIs, to function, the client computer must have the SharePoint Foundation client DLLs installed. The client DLLs must be distributed with the application by using Microsoft's SharePoint Foundation 2010 Client Object Model Redistributable.

For an example that shows how to create a console application that uses the .NET managed object model, see Creating a Basic SharePoint Foundation Client Application.

Silverlight Deployment

For Silverlight client installations, Microsoft SharePoint Foundation 2010 deploys Microsoft.SharePoint.Client.Silverlight.dll and Microsoft.SharePoint.Client.Silverlight.Runtime.dll into the special scripts-only folder %ProgramFiles%\Common Files\Microsoft Shared\web server extensions\14\TEMPLATE\LAYOUTS\ClientBin. This folder is designed to be a standard place for hosting assemblies that are used in Silverlight. You must have both Microsoft.SharePoint.Client.Silverlight.dll and Microsoft.SharePoint.Client.Silverlight.Runtime.dll to develop a solution remotely with the Silverlight object model. The author of a Silverlight application can package the client-side DLLs together in the .xap file for download. It is also possible to cache the Silverlight DLLs.

For information about how to implement the SharePoint Foundation 2010 Silverlight object model in a Silverlight application, see Using the Silverlight Object Model.