Silverlight interview

What is Microsoft Silverlight?

1)Silverlight is a web based technology, launched by Microsoft in April 2007.
Silverlight is considered as a competitor to Adobe's Flash.
2)Silverlight is Microsoft's implementation of a cross-browser, cross-platform client framework that allows designers
and developers to deliver Rich Internet Applications (RIA) embedded in Web pages.
3)It supports advanced data integration, multithreading, HD video using IIS Smooth Streaming, and built-in content protection.
Silverlight enables online and offline applications for a broad range of business and consumer scenarios.
4)One of the design goals of the Silverlight technology is to fill the gap between Windows applications
 and Web applications in terms of creating Graphical User Interfaces (GUI).

Why use Silverlight?

1)It is a cross-browser, cross-platform technology which provides a consistent user experience everywhere it runs.
2)Better development tools -Visual Studio 2010, Expression Blend.
3)It runs a client-side application that can read data and update the UI without interrupting the user by refreshing
 the whole page.
4)It can run asynchronous communications with the server, allowing the UI to continue to function while waiting
 for the server response.It delivers rich video, audio, and graphics.

Which programming language can be used to write the backend of the Silverlight application?

We can either use Visual C# or Visual Basic to code the backend of the silverlight application.
Here backend means the code behind files for the Sivlerlight pages.

Stack Panel
use this for grouping controls in a stack (horizontal/vertical). Controls do not overlapped.

Grid Panel
most flexible, multi row/columns layouts. Similar to a HTML table

What are the goals of Moonlight?

1)To run Silverlight applications on Linux.
2)To provide a Linux SDK to build Silverlight applications.
3)To reuse the Silverlight engine built for desktop applications.

What is the Silverlight plug-in?

1)The Silverlight plug-in is a very lightweight component that is necessary for users to access Silverlight applications.
2)The Silverlight plug-in is responsible for accessing the Silverlight object in the Web page,
 downloading and accessing the XAP package, setting up the program environment, and beginning execution of the application.

What is Silverlight Runtime?

Silverlight Runtime is a browser plug-in to support Silverlight enabled applications.
If the Silverlight runtime is not installed, browsers will not be able to run Silverlight elements in the browser.

What is Silverlight SDK?

Silverlight SDK is a set of tools, documentation, samples, and templates for web developers to enable them to easily develop
Silverlight enabled applications.SDK is not really mandatory to develop Silverlight applications

What are the tools required to develop Silverlight applications?

1)Silverlight runtime:To run Silverlight applications in a web browser, you need to have the Silverlight runtime installed
on the client browser as a plug-in.
2)Silverlight SDK: This includes a set of tools required to compile and build Silverlight controls.
If you are comfortable writing HTML using Notepad and compiling .NET applications from console tools,
 then you just need the Silverlight SDK to develop Silverlight applications.
3)Microsoft Expression Studio - This tool is meant for web designers to create rich visual elements for
Silverlight applications.
4) Expression Studio is recommended for web designers who create rich internet applications with enhanced
visual content and graphics. There are several features provided for creating enhanced graphics elements,
 with lot of options to pick color, font, etc.
5)Download Silverlight Toolkit - This toolkit is a Microsoft project containing Silverlight controls, components,
and utilities that can be downloaded and used in your Silverlight applications. It includes full source code, samples,
 and tests.
6)Download .NET RIA Services - Microsoft .NET RIA Services simplifies the traditional n-tier application pattern
by bringing together the ASP.NET and Silverlight platforms. RIA Services provides a pattern to write application logic
 that runs on the mid-tier and controls access to data for queries, changes, and custom operations.

Which tool to use - Expression Studio or Visual Studio?

If your Silverlight application includes just graphics and visual elements, then you can use Expression Studio.
 However, if you are a programmer and if your Silverlight application includes programming logic,
 then you might want to choose Visual Studio.

What is a .xap file?

.xap file is a Silverlight-based application package (.xap) that is generated when the Silverlight project is built.
A .xap file is the compressed output file for a Silverlight application. The .xap file includes AppManifest.xaml,
 the compiled output assembly of the Silverlight project (.dll), and the resource files referred to by the
Silverlight application

What is a Silverlight.js file? 

Silverlight.js is a helper file which enables websites to create advanced Silverlight installation and instantiation
experiences.
 You can call the createObject and createObjectEx functions defined in this file to embed the Silverlight plug-in in
a web page.

What is the use of the ClientBin folder? 

The ClientBin folder is used to place the .xap file of a Silverlight application.
You can keep it anywhere in your web application, but this is the default location used by Silverlight.

How to change the default page of a Silverlight application? 

To change the default page of a Silverlight application, you need to set the RootVisual property
inside the Application_Startup event of the App.xaml file.
Collapse private void Application_Startup(object sender, StartupEventArgs e) { this.RootVisual = new MainPage(); }

What is XAML? 

1)XAML stands for eXtensible Application Markup Language, and is a declarative markup language that follows
the XML rule and is used for developing User Interfaces in WPF and Silverlight technology.

What is the AppManifest.xml file? 

First, let’s look at an example AppManifest.xaml file: Collapse The first element in AppManifest.xaml
is a Deployment node. This node defines the application, and contains the child AssemblyPart nodes.
As you can see the AssemblyPart nodes define what assemblies (DLLs) are contained within the .xap file,
and give each of them a name.

 What files are contained within the .xap file? 

The .xap file contains an application manifest (AppManifest.xaml) file and all the necessary DLLs that are
required by the application. The first DLL contained is the compiled version of your application and
 has the same name of your application. In my test, I created an application named "SilverlightApplication1",
so the DLL is named "SilverlightApplication1.dll". The rest of the DLLs are the dependencies the application requires.

What is app.xaml? 

1)App.xaml is a file used by Silverlight applications to declare shared resources like brushes, various style objects,
templates etc. Also, the code-behind file of app.xaml.cs is used to handle global application level events
like Application_Startup, Application_Exit, and Application_UnhandledException (similar to the Global.asax file
for ASP.NET applications).
2)This file used to set silverlight application start up page.

What is the Silverlight official name? 

Silverlight was formerly code-named "WPF/E".

What are the main features and benefits of Silverlight? 

1)Compelling cross-platform user experiences.
2)Flexible programming model with collaboration tools.
3)High-quality media, low-cost delivery.
4)Connected to data, servers, and services.

What is MainPage.xaml? 

When you create a Silverlight project using Visual Studio, it creates a default XAML file called "MainPage.xaml".

Which language is Silverlight developed in? 

It was developed using a combination of C# and C++.

What is the difference between WPF and Silverlight?

1)WPF will be used in the development of Rich Windows Graphical User Interfaces (GUI) for Windows client users.
2)Silverlight for developing rich browser based internet applications.
3)WPF is Microsoft’s latest development platform for building next-generation Windows client applications.
4)Silverlight is Microsoft’s latest development platform for building next-generation Web client applications.
5)WPF runs windows only.
6)Silverlight Cross OS, cross browser, cross device.

What is the difference between Silverlight and ASP.NET AJAX?

What are the different Layout controls available in Silverlight?
There are three different types of Layout controls provided by Silverlight:
1)Canvas - Position child elements absolutely in x, y space.
2)StackPanel - Position child elements relative to one another in horizontal or vertical stacks.
3)Grid - Position child elements in rows and columns. You have to add a layout panel to every XAML page you create.
All other UI elements must be added inside one of the layout panels. Each page can have exactly one layout panel control.

What is meant by RIA? 

RIA stands for Rich Internet Applications, which are Web applications with rich user interfaces including
media elements such as audio, video etc. You can think of them as being similar to powerful and rich desktop applications,
 except that RIA applications are Web based.

What is .NET RIA Services? 

Microsoft .NET RIA Services helps to simplify the n-tier application pattern by combining the ASP.NET and
Silverlight platforms. RIA Services provides a pattern using which you can write application logic that can run on
the mid-tier and controls access to data for queries, changes, and custom operations.
It also provides support for data validation, authentication, and roles by integrating with Silverlight components
on the client and ASP.NET on the middle tier.

What is the relationship and difference between Silverlight and ASP.NET?

1)Silverlight runs completely on the client, while ASP.NET mainly runs on the server, but also has a few parts running on the client.
2)Silverlight can’t work with a database directly; instead, it consumes data from Web Services, while ASP.NET has strong support for working with databases directly.

MVVM Architecture‏?

The Model-View-View Model (MVVM) pattern provides a flexible way to build Silverlight applications that promotes code re-use, simplifies maintenance and supports testing. The pattern consists of three different components including the Model (entities and code on the server), the View (the Silverlight screens) and the ViewModel (the glue between the Model and the View.


existing Silverlight application that uses code-behind files for all of the C# or VB code into a more structured architecture that follows the MVVM pattern. Topics covered include creating a service agent class to handle calls to a WCF service, creating a ViewModelBase class, creating a custom ViewModel class and binding a ViewModel to a View declaratively in XAML. You'll also see how commanding can be used to wire-up events in a View to methods in a ViewModel. 

N-Tier Architecture?

If you develop complex business applications with a large codebase that can easily adapt to changing environments you introduce multiple tiers or layers. For example, you create a Data Access Layer that communicates with your data source whatever that is and passes the requested data to the layer above in object oriented form. 

You don’t have ADO.NET libraries in Silverlight so you can’t interact with a database directly (and you shouldn’t do that anyway). So here is what you should have (at least): 

1. Your Silverlight Application - Presentation layer
2. A WCF Service – Service Layer
3. Your Database / additional ADO.NET logic to interact with your database – Persistence Layer