SharePoint 2010 - Complete details about Client Object Model

This is the introduction to the Client Object model introduced in the SharePoint 2010. This is going to be a huge help and useful part in SharePoint 2010 for developers and makes lot of customization to the existing SharePoint system.

In eariler versions, I mean till SharePoint 2007 the code runs using the SharePoint object model to run against the server which is running SharePoint. Other than the SharePoint server object model, other way is, simply reference the web service and use that to get and manipulate data. Then what is the need of SharePoint 2010 Client object model[Cleint OM] concept?

What is Client Object Model?

Client Object Model is introduced in SharePoint 2010 which helps to developers to make things easier to develop the client side applications for SharePoint 2010. Client Object Model can run on the client machines (Where SharePoint is not installed) and communicate with the SharePoint server remotely. This is the great advantage for the SharePoint devs as they don't have to install SharePoint for development any more.

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:

Server side syntax	Client side syntax
SPContext	ClientContext
SPSite	Site
SPWeb	Web
SPList	List

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.

For Managed Client	DLL's needed : Microsoft.SharePoint.Client.dll, Microsoft.SharePoint.Client.Runtime.dll. Find these files in the 14/ISAPI folder. Usually, the location would be at "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\ISAPI".
Silverlight	Microsoft.SharePoint.Client.Silverlight.dll and Microsoft.SharePoint.Client.Silverlight.Runtime.dll. They find at "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\ClientBin".
ECMAScript	SP.js file - The file fund at "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS".

What we need to do is, add the relted file to the project references if it is Managed client or Silverlight and start using the SharePoint objects in the code. If it is ECMAScript then we just need to declare the line     ExecuteOrDelayUntilScriptLoaded(Initialize, "sp.js"); on the top of js file to use the SP object.
**Initialize is some javascript function.**
My next posts will be the examples of each client OM implementation and how to get, manipulate data for better understanding.