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The View Model Style pattern allows a programmer to create an application that has no UI (user interface). The programmer only creates a ViewModel and a Model. A designer with no programming ability at all, is then able to create the View (UI) in Microsoft Expression Blend 4 (or higher). If you are new to the View Model Style pattern, it is suggested that you read Silverlight View Model: An (Overly) Simplified Explanation for an introduction.

It is a very powerful tool for Designers to create functionality in Expression Blend without writing any code. To demonstrate some of it's abilities, I created a number guessing program with no code.

This article picks up from where the Simple Silverlight 4 Example Using oData and RX Extensions ends. This article implements paging. It also showcases some fancy RX Extensions code created by Dave Sexton (http://davesexton.com/). However, it is a bit ironic that Dave Sexton was not that happy with the code (even though I felt it was so perfect it was suitable for framing).

So you want to use OData but you need to secure the data? There are a ton of ways to do this, but this covers a simple way using ASP.NET Forms Authentication.

This is a follow-up to the previous Blog (http://openlightgroup.net/Blog/tabid/58/EntryId/99/Simple-Silverlight-4-Example-Using-oData-and-RX-Extensions.aspx) where we looked a simple Silverlight application that talks to an oData service.

As with the last tutorial, we will not use a database, just a simple collection that we are creating programmatically. This will allow you to see just the oData parts.

Note, for this tutorial, you will also need to download and install RX Extensions from: http://msdn.microsoft.com/en-us/devlabs/ee794896.aspx, and the Silverlight Toolkit from: http://silverlight.codeplex.com.

As with the last tutorial, we will not use a database, just a simple collection that we are creating programmatically. This will allow you to see just the oData parts.

This project uses the View Model Style pattern that allows for a complete separation between program and design. This allows a Designer with no programming ability, to completely change not only the style and look of the application, but also the entire design of the application.

The "Simplified MVVM" pattern allows a programmer to create an application that has absolutely no UI (user interface). The programmer only creates a ViewModel and a Model. A designer with no programming ability at all, is then able to start with a blank page and completely create the View (UI) in Microsoft Expression Blend 4 (or higher). If you are new to "Simplified MVVM" it is suggested that you read Silverlight MVVM: An (Overly) Simplified Explanation for an introduction.

I recently did a blog post where I created a quick application that uses MVVM.

I read a blog post by Phil Middlemiss called A Chrome and Glass Theme - Part 4 where he showed some really cool buttons. Well my example application could use a quick facelift, so I downloaded his code and opened up his project.

With “Simplified MVVM” you can simply place your web service methods in your Model. The problem you run into, is how do you make an asynchronous web service call and fill a collection in your ViewModel? One method I have employed in the past is to pass an instance of the ViewModel to the Model, however, the problem this causes, is that you have now tightly coupled your ViewModel and your Model. It is also difficult to consume your Model from multiple ViewModels when you do it this way.