Samples

I think some of you may have developed an application that requires a lot of roundtrips on the server to retrieve data to be displayed to the user. Every time your application goes to the server it may have to wait for long running query to end its works, perhaps because the data are extracted from an huge database. Then it have to download the data and finally display them onto the screen.

If you have already deal with this kind of interaction you should know that the two connection limit of the web browser can become evident. For some of you that are not aware of this limitation you have to know that due to the RFC 2616 specification, the compliant browsers have not to hammer the network and are limited to make only two simultaneous connections to the server (per domain).

Uploading and downloading images using a WCF service with Silverlight

Quite often, when browsing the web, we encounter a situation where we are required to upload a file. When I want to register myself on a forum, I often get the question if I want to upload an avatar. Or when using a social networking site such as Facebook, I can upload pictures of me doing something that probably no one is interested in. The point I’m trying to make here is that when developing in Silverlight, we’ll also come in a situation where we want our users to upload files such as images to the server.

Introduction

One of the things I found missing in the current Bing Maps product is the possibility to create an elevation surface profile of routes. Perhaps this feature may not seem much on demand but actually affects more people than expected. Think for example about sports events like marathons and cycling races: to see a preview of the elevation profile of the trail would be of great benefit to the participants. But even if you're just simple hikers you might want to know what is the difference in level of your walking or bicycle trip to better understand the effort that it would entail.

Introduction

In the first part of the series, I introduced the application, and created the “ugly duckling” version, where the end user could already browse the and watch the videos. In this part, I am going to add some bling to the app – namely the Intro animation, the ability to skip it, and to replay it. The Intro animation itself is not created with Silverlight, so I will just use it as a video. This part takes heavy use of Visual States, Behaviors and Easings.

Visual States

The application builds on Sample Data for displaying the videos’ metadata, and it uses Visual States to differentiate between the states of the application.

1. Introduction

Beta versions of Silverlight 4 and .NET Framework 4 are already a fact. There are just a few weeks until the official releases. One of the coolest features which will be part of .NET Framework 4 and also will be available for Silverlight applications is the RX Framework. The arising interest around the RX Framework made me roll up my sleeves and start playing around this.
So the first step was to answer several important questions such as: “what is Linq to Events?”, “what is RX Framework?”, and “what is Reactive Programming?” And generally what lies behind these sound terms? Linq to events or RX Framework (also known as Reactive Extensions for .NET Framework) is one and the same designation for a library for composing asynchronous and event-based programs using observable collections.

Introduction

As I promised earlier on Silverlight Show, this screencast series will show how to create the showcase application shown on www.response.hu (you may want to read the interview to get some background information on the project). The screencast series shows a real life example of how designers can add value to a project, and how a developer can support this effort by creating small, reusable behaviors that allow the designer to tweak things to shape the end result to be exactly as he wanted it.

Introduction

In this article we’ll look at building a spider, which can load web pages and extract links. It will then allow the user to select which links it wants to retrieve, which adds more links to the list. It will look something like this:

Building it will involve using a two-way DOM Bridge to interact with JQuery and building some parsing mechanism to use on the HTML we retrieve.

Introduction

Last month I wrote about how we could take some of the new features of Silverlight 4, Webcam control,  and create a simple application that lets you store captured webcam photos to isolated storage and your file system.

In this article we will take this proof of concept and demonstrate how through the use of commanding and binding we can virtually eliminate all code behind and implement to a strong MVVM architectural pattern.

Getting Started

I think few would argue with the value of a strong separation of concerns within the design of an application.

In the previous part of this article I introduced a custom Form control I made for some real world projects. I've briefly explained the reasons why I choose to not use the Silverlight Toolkit's DataForm, just before to show how to build this control, and I've also detailed what I like of the DataForm and what I should retain in my Form control.  One of this features is the validation of the input and it is what I'm about to describe in the second part.

Download Source Code

The databinding in Silverlight directly supports the validation through a couple of attributes, that let the developer specify if the markup extension has to notify validation exceptions to the control binded to a property so it can show the errors to the user.

Working with DataForm I found difficult to use it in many scenarios due to its design. So I've created a control where I do not generate fields but I handle automatic validation and cancel/commit commands enabling also the usage of the control in mvvm scenarios. This is a good starting point to understand about Validation, BindingExpressions and traversing the visual tree.

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The first time I've met the DataForm control - it was some days after its beta release in the Silverlight Toolkit - I was really astounded from its power. It is capable of many wonders: it generates fields detecting the properties of the binded item, it automatically validates the input values using a bunch of attributes in a way similar to ASP.NET Dynamic Data, it manages the workflow passing through Edit, ReadOnly and Insert state, and these are only a small subset of the features it exposes.