.NET Framework 4 Client Profile - Introduction


Hopefully folks have seen Soma’s and Jason Zander’s blogs announcing the availability of Beta 1 of Visual Studio 2010 and .NET Framework 4.
In .NET Framework 4 we introduced a streamlined subset and more compact version of the .NET Framework called the Microsoft .NET Framework 4 Client Profile. The goal of the Client Profile is to improve the deployment size, time, reliability and overall deployment experience for client application users.

The Client Profile contains the functionality that most common desktop client applications (including Windows Forms and WPF applications) would need, so we expect that many client application developers will use it. This will improve the overall application deployment experience when the application requires .NET Framework 4 to be installed.

One of the most important improvement is that Microsoft .NET Framework 4 Client Profile is now supporting all platforms and OS's that are supported by the full Framework including Vista, XP, Win2k3, Win2k8, Windows7, x86/x64 (excluding IA64)

We still expect some applications to target the full .NET Framework 4 if they need to use features that are not included in the .NET Framework 4 Client Profile.

Client Profile in Visual Studio 2010

Visual Studio 2008 introduced multitargeting for application projects to target 2.0 and 3.x versions of the .NET Framework. Visual Studio 2010 has improved multi-targeting in order to allow developers to easily target the new .NET Framework 4 Client Profile.

In Beta 1, when you create a new Windows Forms or WPF application, it targets the full framework by default. To change to targeting to the Client Profile, open the project properties, select the "Application" page, and change the “Target Framework” drop-down to “.NET Framework 4.0 Client Profile.”

C# project example:


VB project example (Project Properties > Compile tab > “Advanced Compile Options…”):


Notice that if you right-click the project and select “Add References…”, the dialog will show only the .NET Framework assemblies that are part of the Client Profile. This is accomplished by using reference assemblies, metadata-only versions of assemblies. The .NET Framework 4 Client Profile Reference Assemblies are located in

%programfiles%\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\Profile\Client

At compile time, the reference assemblies are matched up against the known "Client List" assemblies that are included in the Client Profile. If the project has a reference to a .NET assembly that is not included in the "Client List", Visual Studio will display compile-time errors in the Error List.

Similar to the .NET 3.5 Framework SP1 Client Profile, the project adds a configuration file (app.config) that will specifically declare the application as a "client" application. This declaration indicates to the CLR loader that you are trying to run a Client Profile application. Without the configuration file, the CLR loader thinks that you are trying to run full .NET 4, and if the machine only has the Client Profile installed, it prompts ebd-user to install the full .NET 4. [Note: this functionality is not available in Beta1.]

Enhancement in 4.0 Client Profile vs. 3.5 SP1 Client profile:

Although the concept of a Client Profile is not new and was introduced in .NET Framework 3.5 SP1, the 4.0 Client Profile contains important improvements:


.NET Framework 4 Client Profile

.NET Framework 3.5 SP1 Client Profile

Supported OS

Supported on all platforms and  OS's that are supported by the .NET Framework (excluding IA64 and Server Core role in W2K8)

Supported only on Windows XP 32-bit machines that did not have any .NET Framework version installed.

(Client Profile will install the full 3.5 SP1 Framework under the covers otherwise)


Supports redistributable as well as web download

Supports Web download only

Add Remove Programs entries

The full Framework comprises the Client Profile and another part called “Extended” thus it has two entries in the  Add Remove Programs dialog (or Programs and Features window).

To remove (or repair) the full Framework you must remove the Extended part first, then the Client part.

If you installed the full Framework, you can go to the Client Profile by removing “Extended” from Add/Remove Programs.

Single entry in Add Remove Programs

Visual Studio

Improved support for Client Profile targeting in Visual Studio 2010



Includes new .NET 4  features (such as Managed Extensibility Framework (MEF), C# 4 Dynamic Keyword, etc)


What’s in and what’s not included in the Client Profile:


full Framework

Client Profile

Common Language Runtime


Can be installed side-by-side with older versions of the Framework

In-process side by side support

Improved COM interop


Innovations in the Visual Basic and C# languages


statement lambdas

implicit line continuations

dynamic dispatch

named/optional parameters


Base Class Library Improvements


Managed Extensibility Framework

Additional core data structures

I/O Improvements


Parallel Computing Innovations


Task Parallel Library (TPL)

Parallel LINQ (PLINQ)




REST-based exposure of relational data

Entity Framework, LINQ to Entities

SqlClient, OLEDB, ODBC Managed Providers






Runtime design libraries for Entity Framework and ADO.NET Data Services


ASP.NET Innovations


ASP.NET AJAX Improvements


XAML Parser



More extensibility during XamlReader.Load and XamlWriter.Save

Ability to use generics               

Better References by Name


Windows Communications Foundation


WCF Client Component

WCF Workflow Services

Service discovery


Router service


Simplified configuration

Improved queuing

REST support

Improved performance


Windows Presentation Foundation


New line-of-business controls including charting control, smart edit, data grid, and others that improve the experience for developers who build data centric applications

Support in for Windows 7 multi-touch, ribbon controls, and taskbar extensibility features

Added support in WPF for Surface 2.0 SDK


Windows Workflow Foundation


Improved activity programming model


Improved designer experience


New flowchart modeling style


Expanded activity palette


Workflow-rules integration


New message correlation features


Significant performance gains for WF-based workflows





Speech support


Various perf counters


MSBuild support


Visual Basic compiler and other compilers


• Full Support

Partial Support


Download and feedback

Please download the Client Profile from the download site here and provide us with feedback. We really would love to know:

  • What do you feel should be the size of the Client Profile?
  • Does it currently contain the right features set? What functionality is missing?
  • To reduce size, what functionality should be removed?
  • How easy it is to use in Visual Studio 2010?
  • Any other feedback?

Notes and caveats:

  • Redistributable package size for the Client Profile is not final (it is currently at ~34MB). Expect to see a smaller size by RTM. Web installer is also not supported in Beta 1
  • Note that the setup package file name includes the word “Client” vs. “Full” to differentiate between the two packages. (e.g. dotNetFx40_Client_x86.exe, dotNetFx40_Full_x86.exe)
  • Setup may require a reboot, depending on the OS and currently running programs during installation.
  • No bootstrapper package is available yet, so you will not find the .NET Framework 4 ClientProfile in Visual Studio 2010's "Prerequisites" dialog in the project's "Publish" property tab.
  • We are still tweaking what should be included in Client Profile vs. full Framework, so it is very likely to change before RTM.
  • Support for the Client Profile Configuration Designer is not available in Beta 1 and likely will not be available before RTM.