WCF related Interview Questions

WCF provides a runtime environment for services, enabling you to expose CLR types as services, and to consume other services as CLR types. WCF is part of .NET 3.0 and requires .NET 2.0, so it can only run on systems that support it.

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1.) What is Proxy and how to generate proxy for WCF Services?

The proxy is a CLR class that exposes a single CLR interface representing the service contract. The proxy provides the same operations as service's contract, but also has additional methods for managing the proxy life cycle and the connection to the service. The proxy completely encapsulates every aspect of the service: its location, its implementation technology and runtime platform, and the communication transport.

The proxy can be generated using Visual Studio by right clicking Reference and clicking on Add Service Reference. This brings up the Add Service Reference dialog box, where you need to supply the base address of the service (or a base address and a MEX URI) and the namespace to contain the proxy.

Proxy can also be generated by using SvcUtil.exe command-line utility. We need to provide SvcUtil with the HTTP-GET address or the metadata exchange endpoint address and, optionally, with a proxy filename. The default proxy filename is output.cs but you can also use the /out switch to indicate a different name.

SvcUtil http://localhost/MyService/MyService.svc /out:Proxy.cs

When we are hosting in IIS and selecting a port other than port 80 (such as port 88), we must provide that port number as part of the base address:

SvcUtil http://localhost:88/MyService/MyService.svc /out:Proxy.cs

2.) What attachments protocol will be used in Windows Communication Foundation?

SOAP Message Transmission Optimization Mechanism (MTOM) will be the attachment technology supported in Windows Communication Foundation.

3.) Does Windows Communication Foundation support both synchronous and asynchronous messaging?

Yes. Windows Communication Foundation supports multiple message patterns, including one-way, request/response, two-way (duplex), and queued.

4.) What specifications will Windows Communication Foundation support?

Windows Communication Foundation will support a broad range of Web services standards, including basic standards (XML, XSD, XPath, SOAP, WSDL) and advanced standards and specifications that comprise the WS-* architecture. These include WS-Addressing, WS-Policy, WS-Security, WS-Trust, WS-SecureConversation, WS-ReliableMessaging, WS-AtomicTransaction, WS-Coordination, WS-Policy, and MTOM.

5.) How are Windows Communication Foundation services hosted?

A class implementing a Windows Communication Foundation service is typically compiled into a library. By definition, all libraries need a host application domain and Windows process to run in. Windows Communication Foundation provides two options for hosting libraries that implement services. One is to use a host application domain and process provided by the Windows Activation Service (WAS), while the other allows a service to be hosted in any application domain running in an arbitrary process (such as a Windows Forms application, a console application, an NT Service, etc).

Silverlight Interview Materials

Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of Microsoft .NET–based media experiences and rich interactive applications for the Web.

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1.) What features are missing from Silverlight presentation markup that will be supported in WPF (Windows Presentation Foundation)?

Some high-end Windows specific features of WPF, such as real 3D, hardware-based video acceleration, and full document support, will not be supported in Silverlight. This is by design in order to serve Silverlight’s cross-browser, cross-platform reach scenario that demands a light weight plug-in. That being said, Silverlight will offer a uniform runtime that can render identical experiences across browsers on both Mac OS and Windows.

2.) Will Silverlight-based applications and content run on any Web Server? What are the benefits to running it on servers running Windows?

Silverlight works with any web server just like HTML. Video and audio content can also be progressively downloaded and played back from any Web server platform. Benefits of Windows server-based distribution of Silverlight applications include Windows Media Services with Fast Stream (instant playback) and Fast reconnect technologies, lower distribution costs (streaming users only download what they watch), and tap into the full Windows server ecosystem of platform components and partner solutions. Those benefits will be enhanced in the future version of Windows Server (code name “Longhorn”) and with Internet Information Server 7 (IIS).

3.)  Is Silverlight supported on various locales?

Silverlight installs on localized versions of Macintosh computers and Windows. At this time, the installation is available in an international English format. Final releases will render international text (using double-byte characters) and support the full 64K Unicode character set. Silverlight uses simple input mechanism that treats all the languages in the same way.

4.) What are the different ways to display text with Silverlight?

Silverlight supports displaying static preformatted text that is comprised out of glyph elements and also dynamic text that uses TextBlock. With glyphs, one needs to position the characters individually while TextBlock supports simple layout.

5.)  What kinds of fonts are supported with Silverlight?

Beyond standard and western fonts, Silverlight also supports East Asian characters, double-byte characters, and can work with any East Asian font or Middle Eastern font by using the glyphs element and a supporting TrueType font file that supports the requested glyph.

6.)  What is Microsoft® Silverlight^TM Streaming by Windows Live^TM?

Microsoft® Silverlight^TM Streaming by Windows Live^TM offers a free cloud-based hosting and streaming solution for quickly delivering high-quality, high-scale, cross-platform, cross-browser, media-enabled RIAs.

7.)  How much does Silverlight^TM Streaming cost?

While the product is in Beta, hosting is free of charge. Up to 4 GB of data and streaming is free of charge up to 700 kilobit/s. At the conclusion of the Beta program, the developer can chose to enable Microsoft-sponsored advertising in the application for continued free use of the service to or subscribe to a pay-for-use service that is free of advertisements.

8.)  What video encoding formats are supported?

The designer or developer is free to use any encoding format for their video supported by the Windows Media Video codec. This includes Variable Bit Rate (VBR) encoding for DVD-quality video and the use of the VC-1 codec for high-definition content. However, for HD content, be aware that the maximum output rate from the service is 700 kilobit/s, which means the client will not receive real-time delivery of HD video.

9.)  Do you support digital rights management to protect my videos?

In the future, Silverlight^TM Streaming will provide support for DRM-encoded video as an optional paid turnkey offering.

10.)  What applications will Microsoft provide to make hosting easy?

Microsoft is building a simple uploading tool and working to add publishing support directly to Silverlight^TM Streaming via Expression^TM Media Encoder, a feature of Expression^TM Media. In addition, third-party companies are adding support to their own applications for Silverlight^TM Streaming.

11.) How is my content secured from unauthorized access?

You will have to be signed into the Silverlight^TM Streaming service to manage your account and your Silverlight applications. Your Silverlight^TM Streaming ID and secret key, associated to your Windows Live ID, will authenticate you as the unique and legitimate owner of the applications and content you upload to the service. You will also need this information to manage your Silverlight applications using the API. The Silverlight^TM Streaming ID is public. However, the secret key should be kept confidential.

12.)How do I get started?

To sign up for your free account, visit streaming.live.com. Anyone with a Windows Live ID can participate.

Silverlight Interview Materials

Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of Microsoft .NET–based media experiences and rich interactive applications for the Web.

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1.) Is Silverlight the official name for "WPF/E"?

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

2.) Does silverlight web application work with all browsers ?

Yes, A web application developed by silverlight technology can work with any browser

3.)What are the main features and benefits of Silverlight?

-Compelling cross-platform user experiences.

-Flexible Programming Model with Collaboration Tools.

-High-quality media, low-cost delivery

-Connected to data, servers, and services

4.) How can I build experiences and applications with Silverlight?

Silverlight development tools include role-specific productivity tools for both designers and developers:

• Expression Studio empowers designers to create interactive UI and media-rich experiences, prepare media for encoding and distribution, and create W3C standards-compliant sites using modern XHTML, XML, XSLT, CSS, and ASP.NET. Expression Design includes support for exporting XAML for Silverlight. At MIX 07, Microsoft released Expression Blend 2 May Preview and Expression Media Encoder Preview to enable designers to build media experiences and RIAs.
• Visual Studio empowers developers to develop client and server code using full IntelliSense, powerful debugging, rich language support, and more.

By using Expression Studio and Visual Studio, designers and developers can collaborate more effectively using the skills they have today. Additionally, Silverlight supports a consistent subset of XAML (eXtensible Application Markup Language) for declarative programming, the same format found in .NET 3.0. Because XAML is toolable, there is always the potential for third-parties to provide additional XAML-based Silverlight tools in the future.

5.) How does Silverlight make the Microsoft development system better?

Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of media experiences and rich interactive applications (RIAs) for the Web. Examples include:

• For ASP.NET-based Web applications, Silverlight provides a rich UI front-end that, with a consistent programming model, adds support for richer interactivity, media, and audio.
• For Microsoft SharePoint–based content, Silverlight offers the ability to create rich Web parts.
• For Windows Live services, Silverlight offers the ability to consume services and APIs more effectively. 

6.) What audio or video formats are supported in Silverlight?

Silverlight supports Windows Media Audio and Video (WMA, WMV7–9) and VC-1, as well as MP3 audio. Additional formats may be available by the final release based on customer feedback.

7.)  Will Silverlight support all the codecs Windows Media Player supports?

Since Silverlight is a lightweight cross-platform technology, it only carries the most common codecs that are needed for Web playback. However, we are gathering information from customers about the needed codecs and can update Silverlight when necessary.

8.) Will Silverlight support digital rights management?

For content providers, Silverlight will support digital rights management (DRM) built on the recently announced Microsoft PlayReady content access technology on Windows-based computers and Macintosh computers.