Using LINQ and REST in SharePoint 2010

Among the new APIs available for SharePoint 2010 developers the 2 new most significant ones are LINQ and REST.

While developing server side code, you can now make use of LINQ to query your lists instead of using CAML.
The benefit of using LINQ is clear, working with strong typed objects and cutting down the development effort by a lot.
The problem comes when you are not sure what type of lists you are going to work on, and if you wish to support custom lists created by customers.
Before you can use LINQ on SharePoint you need to create an object that represent that list structure, and once the list changes (the fields you are querying are removed to renamed) you will not be able to use it anymore :(

But - remember, working on the server site with the SPList object is dengerous as well, as all you get are item[field_name] resutls, which is not strongly types and requies many validations to be done!

While working on the client side, you will be able to work using the client side object model (much like the server side, using Site/Web/List instead of SPSite/SPWeb/SPList we have on the server) but still that will not be strongly typed for you.
The news are that you will be able to use LINQ in the client side, that will allow you to automatically render the correct proxy objects in the client side (accessible from javascript / silverlight) and will be strongly typed!

So, by all means - start learning SharePoint REST syntax and commands...
here are some available commands to get you started:
$filter=
$expand=
$orderby={property}
$skip=n
$top=n
$metadata – bring all metadata of that object

These commands are accessible under the REST service URL which includes (sometimes) the entity name you wish to run against, like so:
http://site/subsite/_vti_bin/ListData.svc/{Entity Name}/{Options...}

This service URL can be registerd to the client using the standard ASP.NET AJAX way for registring services, and everything is made simple after that!

(If you need more info on ASP.NET AJAX you should definitly check these how-to's by Joe Stagner here: http://www.asp.net/learn/ajax-videos/ and specifically on registring services here: http://www.asp.net/learn/ajax-videos/video-82.aspx)

Well, are you excited as I am to move onto SharePoint 2010 yet? :)

How to override the sandboxed current site execution limitation

When you publish a solution in SharePoint as a sandbox solution, we already talked about that the proxy API will block any access to other remote site collections.

An easy override to this is simple - simply use the client API and you will be able to access any share point site you wish without going through the proxy API that a sandboxed solution uses.

Client API in SharePoint 2010

This is what I picked up in todays great session on client code;

Basically, Microsoft.SharePoint.Client is a wrapper that you can use at the client side (silverlight or javascript) to add get and update information.
Migration of code will require start using the Client API objects instead of the current API we all know in the server, but most objects are similar to help us update our code easily.
So - SPWeb will be web, SPList will be list etc...
Event SPContext exists as ClientContext!
the only difference is, that you run all your code on the clientContext object in the client side, and once you have a set of operations you wish to submit to the server you can do that by calling "clientcontext.ExecuteQuery()" or "clientcontext.ExecuteQueryAsync()" if you want the UI not to wait for the result.
If you wish to retrieve data form server to your client you can use the “Load” or “LoadQuery” methods. LoadQuery will return a result collection and will use method syntax or linq query syntax. It will build you XML query and will send them to the server next time you call “ExecuteQuery”.
Using the "Execute" or "Load" methods actually help reduce the number of trips done from the client to the server to reduce server load, bandwidth and improve responsiveness.
Nothing new, except you don't have to build your own wrapper and web services if you want to run some code on your SharePoint from the client. Basically this will communicate with client by dropping JSON code from the server to the client, the client will use the JSON to work with and send queries to the server in XML format.
I guess this will help us do less post back, as this will not be supported in wiki pages (no post back support).
A new cool thing is the SP.CamlQuery.CreateAllItemsQuery() method that renders a CAML that returns all items for a list. This will surly get you started with CAML query – the last stand of CAML in 2010 since views and forms are now defined by XSL.

More news from the SPC2009 will follow!