Neil Bostrom: Tech Ed 2008 - Day 2

Learning the Entity Framework

Entity Framework is one topic I really wanted to learn more on, however this was not the session to achieve that. The content of the session was only the basics which I already knew. The practical demos were limited. Felt a little let down when I left the session as I missed out on some other interesting topics to make sure I made that session.

Sync Framework - Deep Dive

Sync framework was an excellent session covering everything from what the sync framework is right down to how to write a custom provider for it. The Sync framework allows you to sync almost anything (if you have a provider for it) with anything else. So you could sync a file system with a database, or outlook with facebook etc. This solution would have been a perfect for the Hippo PDA project where we had to write all the synchronisation manually.

Building a Dynamic Info-Screen application with Silverlight 2.0

I was extremely pleased with this session as it was showing a practical implementation of Silverlight in a real world application. The Info screen was talking about ad boards or train station screens, where you need dynamic content inside a range of different templates. Max Knor did an excellent job explaining the architecture of the application and also showing real code to swap in and out dynamic templates in Silverlight. The application showed some of the great power you have with Silverlight, including the ability to run the Silverlight on a client inside a WPF application.

How LINQ Works: A Deep Dive into the C# Implementation of LINQ

This session was a level 400 (uber hardcore) and it was great! Luke Hoban did a fantastic job covering a difficult topic in an easy to understand manner. It covered how LINQ holds together and how the C# compiler converts the LINQ expressions into method calls. Interesting point I learnt here is that the compiler will search closest to the code for extension methods. This means you can override the default implementation of an extension method (like the WHERE clause) by declaring it closer than System.Linq. Luke then covered how IQueryable uses expression trees to allow delayed execution. This is the real power behind LINQ. A real gem that came out when was Luke showed the different code that is generated by the compiler depending on which interface you work against, IQueryable or IEnumerable. IEnumerable lambdas are generated as methods on the class, however IQueryable lambdas are created as expression trees. It's a difference I knew about but didn't join the dots to the different code that is generated.

Silverlight 2.0 Security End to End

Security is not a word I’ve heard being mentioned with Silverlight yet, this is why I jumped at this session when I saw it. Silverlight is very powerful but does run client side so security is a concern. The first area covered was the built in security that the Silverlight CLR uses. It has a SecurityCritical attribute applied to it that is used by the platform Silverlight code, like File.Exists. This code can only be used by the Silverlight framework. There is also a SecuritySafeCritical attribute to allow application code to call code that is SecurityCritical locked. All Silverlight appdomains are sandboxed, no Silverlight app can create app domains or cross call them. To allow Silverlight apps to store settings, there is an Isolated storage class. This is a Virtual File System as it needs to work on both PCs and MACs. The Isolated Storage is per application or per domain. The default space allocation in the Isolated Storage is 1MB, however the developer can prompt the user to request more space. Webservice calls are only allowed to same domain, port and protocol. To make cross domain calls, you need a clientaccesspolicy.xml in the root of that site. We spoke about good practices on securing web service calls by using Querystring tokens when making the calls.