I’ll be doing a session on Astoria at REMIX Boston 07 (10/8-10/9) and at the New England Code Camp (9/29-9/30).

What is Astoria?

Astoria exposes data as web services through an Entity Framework Data Model. Once exposed, you can use URI based syntax to query data through the conceptual layer of the entity data model. You can control what is and isn’t exposed and you can also do inserts, updates and deletes. The results can be output in a number of formats including JSON and ATOM.

It’s simplest to understand this by looking at some queries in a web browser. The Astoria CTP add-in for Visual Studio 2008 Beta 2 has a template for creating a Web Data Service that looks like a WCF service. It only needs one class to expose the whole kit n’ caboodle and that class inherits from WebDataService, a generic class. You merely need to tell that class that the type it is dealing with is the Entities class exposed by an Entity Data Model that you have created. The class doesn’t even have any code in it.

  public class northwind : WebDataService<NorthwindModel.NorthwindEntities>
    {
    }

Then you can just make calls to that service and start playing with the query syntax.

The base service exposes the list of entities in the model (http://mysite/myservice.svc). The payload is just a raw XML representation of the data. There will be payloads for different formats, such as JSON, ATOM and more. See this Astoria team blog post for more info.

Then you can start drilling in. Here for example, I have asked for the Categories entities. It will return all entities with their details.

Now you can start seeing the URIs that are displayed to show you how to drill further into data. When looking at it in the browser, you might want to click on those URIs, but remember, in a real app this is not how you will be working with the results of the service call. 🙂 Note that you can see how to get to the related Products data although it is not pulled in automatically. That’s no different than how Entity Framework works by default – deferred loading of related data.

So let’s try the Category uri for categoryID 2.

And then get the products for that category.

So you can see now the basic concept of what Astoria is doing. I am not forced to write a billion operations in my web service to expose my data every which way. I don’t have to deal with building xmldocuments to return data that can be consumed by anyone, not just .NET clients that can deal with serialized datasets. With proper security in place and the possibility of customizing what is and isn’t exposed (and how), consumers of my data can now have easy access to do all kinds of reporting, mash-ups and more. The fact that any consumer will know what to do with any data that is exposed via an astoria web data service is huge.

You can learn more about Astoria by following the Astoria Team blog.

Erick Thompson is at SQL PASS and will be doing a talk on Entity Framework for DBAs tomorrow (Wednesday) afternoon.

You can get a preview of what he will be talking about by reading his recent post on the topic.

Just a quick pointer to Pablo Castro’s announcement that a new CTP for Astoria is out that will work with vS2008 Beta2.

An important note, this is a refresh of the CTP, which is based on the early prototype. The actual production code that they are working on is a totally different set of bits. Hmm, for safetey’s sake, I better just quote Pablo:

NOTE: let me stress that this is a refresh of the May CTP, which is based on the initial prototype of Astoria. All of the features/design options we’re discussing here in this blog (e.g. last post about payload formats) are in the context of the production version of Astoria which we are in the process of building. The production version incorporates a ton of feedback that we received over the last few months plus our own more detailed thinking of what should the system look like. So expect to see quite a few differences between the CTP and the production code once we start shipping the production version. The principles will all be the same, but the details will vary.

I watched part 2 of Jim Wooley’s ASP.NET Podcast show on LINQ and was really impressed with the creativity of his examples. Having dug deeply in order to write LINQ in Action along with Fabrice Marguerie and Steve Eichert, he’s way past the how-to basics and able to see the bigger picture of leveraging LINQ.

In his demo, he starts with some simple querying of the file system – a good demonstration of using linq against objects, but by the time he gets to the end of the demo, he is using JOIN to build queries that combine file system info with data pulled from the database.

I knew I wanted to do something like that but I couldn’t just copy him, no matter how flattering. So I thought about it for a while… what data is on my computer that I might want to extend with some database data? Then I thought of Outlook.

Thankfully, John Goalby had already written some posts on querying Outlook data with LINQ. So I was well on my way!

I created a few new email accounts for some employees of companies in AdventureWorksLT and sent emails to myself with their accounts. Then I created contact records for them in Outlook in my own account, making sure that I typed in the company names to match the database. Now I had some test data.

First I tested out a query where I joined MailItems from my inbox with ContactItems from my contact. (Note that I did this in VB since John’s examples are in C#, so this gives a little more sample code for people to discover.)

Dim ol As Outlook._Application = New Outlook.Application
Dim inbox = ol.ActiveExplorer().Session.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox)