Hardware requirements for Windows Phone 7 Part 1 – Buttons, Screen, Cameras, Keyboards, Wireless, Bluetooth, CPU

To MEF or not to MEF?

Did you ever wanted to build a modular application? You know when you program against interfaces rather than actual implementation, and the implementation is likely to change anytime? The implementation resides in building blocks and you can just replace these building blocks whenever you want. Or maybe you wanted to build an extensible application that can work nicely with plug-ins. I could go on and on with examples but in general, we can say that we have an application and a couple of modules, extensions, building blocks, whatever, and we just want to ”plug” them into our application, without writing any more plumbing code or applying any modification.

Introduction

In this article I will show you how to capture a “screenshot” of a Silverlight application. Fortunately, since Silverlight 3, this is straight-forward to do with the WriteableBitmap class. I’m also going to show how to use the screen capture for special effects, or for saving to file as a JPG. This article is aimed at developers who are fairly new to Silverlight.

Here is a Silverlight app that demonstrates the approach we are going to use:

You can grab the source here.

Introduction

In this short series of articles I’ll cover what MVVM is and how to use it in practice, how to solve issues when applying this pattern and how to take advantage from it.

1. Part I: The Basics
2. Part II: Messaging, Unit Testing and moving to a live data source
3. Part III: Validation, Closer integration with the view 

In the previous articles we created a simple master details scenario with the MVVM pattern. We used mock and live data sources with WCF, we created unit tests, we used Messaging from the MVVM Light Toolkit.

By now, we have an application that communicates with a server, and we know how to send data back to a server.

Introduction

In this short series of articles I’ll cover what MVVM is and how to use it in practice, how to solve issues when applying this pattern and how to take advantage from it.

1. Part I: The Basics
2. Part II: Messaging, Unit Testing and moving to a live data source
3. Part III: Validation, Closer integration with the view

In the previous article we discussed what MVVM is and why it matters. In this article we’ll try to benefit from the pattern and talk about the issues you have to battle through when working with MVVM. Our sample application was able to pull some data from a model, and display it on the screen in a master-detail fashion.

What is MVVM and why do you need it?

Do you know the feeling, when you start to develop an application, and in the first couple of days you feel good because you made a really good progress? Do you know the feeling, when after a couple of days, you feel that your design is not that best and when you have to modify a little code, you are afraid of the effect it might have on other parts of you code? The first sign of a bad design is when applying a hack is easier than to implement it the proper way.

Introduction

Recently I have been working on a project, where a certain task's completion needs to be visually indicated in some graphic way. I settled on creating a style for the ProgressBar control, with a changing background color depending on the current value of the ProgressBar.

 HSV (Hue-Saturation-Value)

From Wikipedia :

"HSL and HSV are the two most common cylindrical-coordinate representations of points in an RGB color model, which rearrange the geometry of RGB in an attempt to be more perceptually relevant than the cartesian representation."

HSV is a different way of representing a color (as opposed to RGB, where R indicates a value from 0 to 255 that "controls the amount of red", G for green and B for Blue). Have a look at the link above for an in-depth discussion.

This article is Part 1 of the series WCF RIA Services:

1. Getting Started with WCF RIA Services 
2. Querying Data Through WCF RIA Services
3. Updating Data Through WCF RIA Services
4. WCF RIA Services and MVVM
5. Metadata Classes and Shared Code in WCF RIA Services
6. Validating Data with WCF RIA Services
7. Authenticating and Authorizing Calls in WCF RIA Services
8. Debugging and Testing WCF RIA Services Applications
9. Structuring WCF RIA Services Applications
10. Exposing Additional Domain Service Endpoints for Other Clients

Introduction

In order to build serious business application in Silverlight (and other client technologies), you have to work with a lot of data. And that data is usually not resident on the client machine, it is usually distributed amongst many clients and is stored and operated on by back-end services. If you try to write this kind of application architecture yourself, you have to tackle a lot of technologies and write a lot of plumbing. In the end, most of what you are doing is pushing and pulling data from the client to the back end and invoking operations on the server from the Silverlight client application.

Download the sample here: SilverlightPlayground.Pop3Sample.zip (40KB)

There are plenty of ways to handle network communications in Silverlight, but also with this great number of tools, the task is not always simple. The main problem is due to the need to always make calls to the network in an asyncronous way. If this is not a great trouble when we use a traditional HTTP channel, it may become source of headaches when you have to implement a low-level network protocol using a socket. When you have to handle this situation it is often required by protocols to exchange a great number of small messages, each with its own format, size and syntax, so the programming become a sort of push & pull game with a huge number of methods, hard to handle when you are debugging or maintaining the software.