Visual Studio 2012

For those who aren't familiar with the main elements of .NET development there is the common language runtime (CLR), the .NET Framework, the various language compilers and Visual Studio. Each of these plays a role; for example, the CLR—covered in Chapter 2—manages the execution of code on the .NET platform. Thus code can be targeted to run on a specific version of this runtime environment.

The .NET Framework provides a series of classes that developers leverage across implementation languages. This framework or Class Library is versioned and targeted to run on a specific minimum version of the CLR. It is this library along with the language compilers that are referenced by Visual Studio. Visual Studio allows you to build applications that target one or more of the versions of what is generically called .NET.

In some cases the CLR and the .NET Framework will be the same; for example, .NET Framework version 1.0 ran on CLR version 1.0. In other cases just as Visual Basic's compiler is on version 10, the .NET Framework might have a newer version targeting an older version of the CLR.

The same concepts carry into Visual Studio. Visual Studio 2003 was focused on .NET 1.1, while the earlier Visual Studio .NET (2002) was focused on .NET 1.0. Originally, each version of Visual Studio was optimized for a particular version of .NET. Similarly, Visual Studio 2005 was optimized for .NET 2.0, but then along came the exception of the .NET Framework version 3.0. This introduced a new Framework, which was supported by the same version 2.0 of the CLR, but which didn't ship with a new version of Visual Studio.

Fortunately, Microsoft chose to keep Visual Basic and ASP.NET unchanged for the .NET 3.0 Framework release. However, when you looked at the .NET 3.0 Framework elements, such as Windows Presentation Foundation, Windows Communication Foundation, and Windows Workflow Foundation, you found that those items needed to be addressed outside of Visual Studio. Thus, while Visual Studio is separate from Visual Basic, the CLR, and .NET development, in practical terms Visual Studio was tightly coupled to each of these items.

When Visual Studio 2005 was released, Microsoft expanded on the different versions of Visual Studio available for use. Earlier editions of this book actually went into some of the differences between these versions. This edition focuses on using Visual Studio's core features. While some of the project types require Visual Studio Professional, the core features are available in all versions of Visual Studio.

In Visual Studio 2008, Microsoft loosened the framework coupling by providing robust support that allowed the developer to target any of three different versions of the .NET Framework. Visual Studio 2010 continued this, enabling you to target an application to run on .NET 2.0, .NET 3.0,.NET 3.5, or .NET 4.

However, that support didn't mean that Visual Studio 2010 wasn't still tightly coupled to a specific version of each compiler. In fact, the new support for targeting frameworks is designed to support a runtime environment, not a compile-time environment. This is important, because when projects from previous versions of Visual Studio are converted to the Visual Studio 2010 format, they cannot be reopened by a previous version.

The reason for this was that the underlying build engine used by Visual Studio 2010 accepts syntax changes and even language feature changes, but previous versions of Visual Studio do not recognize these new elements of the language. Thus, if you move source code written in Visual Studio 2010 to a previous version of Visual Studio, you face a strong possibility that it would fail to compile. However, Visual Studio 2012 changed this, and it is now possible to open projects associated with older versions of Visual Studio in Visual Studio 2012, work on them, and have someone else continue to work in an older version of Visual Studio.

Multitargeting support continues to ensure that your application will run on a specific version of the framework. Thus, if your organization is not supporting .NET 3.0, .NET 3.5, or .NET 4, you can still use Visual Studio 2012. The compiler generates byte code based on the language syntax, and at its core that byte code is version agnostic. Where you can get in trouble is if you reference one or more classes that aren't part of a given version of the CLR. Visual Studio therefore manages your references when targeting an older version of .NET, allowing you to be reasonably certain that your application will not reference files from one of those other framework versions. Multitargeting is what enables you to safely deploy without requiring your customers to download additional framework components they don't need.

Complete coverage of all of Visual Studio's features warrants a book of its own, especially when you take into account all of the collaborative and Application Lifecycle Management features introduced by Team Foundation Server and its tight integration with both Team Build and SharePoint Server.