How does a Queryable Load work in SharePoint?

Question

Could anybody help me to understand what kind of work is going behind the scene, when LINQ is used for retrieving SharePoint objects. For example, I can use a code like this:

private IEnumerable<List> newLists;

var dt = new DateTime(2010, 3, 20);
var query = from list
            in clientContext.Web.Lists
            where list.Created > dt && list.Hidden == false
            select list;

newLists = clientContext.LoadQuery(query);
clientContext.ExecuteQuery();

How does it work?

How does request look like?

From documentation I found:

When you use the CSOM, you can write LINQ queries against client-side objects, such as lists and Webs, and then use the ClientContext class to submit these queries to the server. It's important to understand that when you take this approach, you are using LINQ to Objects to query SharePoint objects, not LINQ to SharePoint. This means that your LINQ expressions are not converted to CAML and you will not see the performance benefits that are associated with CAML conversion.

So, I was little bit confused, because I thought, that LINQ expression is transformed to Caml request. I can't understand how does it work. How can I watch details of request while executing ExecuteQuery() method? Could you please recomend me any tools for watching requests?

Answer 1

SP uses CAML internally: SP runtime converts Linq to CAML and send it via Soap request, or REST statement (if you are using RESTful services): http://msdn.microsoft.com/en-us/library/ff798339.aspx (with examples);

See more here: http://msdn.microsoft.com/en-us/library/ff798464.aspx

and this can be helpful: http://nikspatel.wordpress.com/2012/08/05/sharepoint-2010-data-querying-options-server-om-vs-client-om-vs-rest-vs-linq-vs-search-api/