We can optionally retarget our project to work with a later
version of .NET by right-clicking on the project within the solution explorer
and by bringing up its properties dialog. We can select the “target
framework” dropdown within it and select the version of the .NET Framework we
want to target:
Figure 5
We can choose from a variety of different .NET
versions above. Included in the list is the "Server Core” profile
that supports the GUI-less version of Windows Server 2008 R2 – and which does
not support certain APIs. Because the reference assemblies we use for
metadata and intellisense can support any version or release, we’ll even be
able to distribute versions of them with future service packs if they introduce
any new APIs (enabling 100% accuracy).
For this walkthrough, we’ll choose to move the
project to use .NET 4.0. When we do this, VS 2010 will automatically
update the project reference assemblies and the web.config file of our project
to properly reflect the new version.
Once we do this, VS 2010 will filter the
toolbox and markup intellisense to show us all of the new controls and
properties available in the ASP.NET 4.0 version. For example, the
property grid below now displays the new “ClientIDMode” property available on
all controls in ASP.NET 4.0 - which gives you the ability to control how client
id’s are output and avoid ugly client ids (a new ASP.NET 4.0 feature I’ll cover
in a later blog post):
Figure 6
Now that we’ve upgraded the project to use .NET 4.0, VS 2010
will also now show us code intellisense for the new types and methods/properties/events
on types in .NET 4.0. For example, below you can see some of the new
redirect methods available on the ASP.NET 4.0 “Response” object (which
previously did not show up when the project was targeting .NET 2.0):
Figure 7
The new Response.RedirectPermanent() method
above makes it easy to issue “HTTP 301 Moved” responses – which can avoid your
site accumulating stale links in search engines. The URL Routing engine is now
supported by both ASP.NET Web Forms and ASP.NET MVC based applications, and the
new Response.RedirectToRoute() method allows you to easily redirect to a route
declared with it.
And lastly when we run the application using
the built-in VS web-server, VS 2010 will now run it using the ASP.NET 4.0
version:
Figure 8
