TechNet Express: What is new in Dot.Net 4.5

http://msdn.microsoft.com/en-us/library/ms171868%28v=vs.110%29.aspx#tailored

Compatibility Enhancement

Since project files are same in both VS2011 and VS2010 so you can open Visual Studio 2010 projects in Visual Studio 11 and continue working from Visual Studio 2010 without any problems.

VS 2011 IDE Enhancement

Simplified Toolbar :Tool bar is much simpler and by default have only most frequently used command
Quick launch box (Command Search) : This feature I would love to have.Search for and execute any command you need. You do not need to look through all the menus or memorize shortcuts. Start typing a command name in the quick launch box,
Search in Solution Explorer: The new Solution Explorer has also added an integrated search.
Pin Tab: Visual Studio now provides the ability to pin tabs. This enables you to easily keep the files you use most on the left-hand side of the tab well. Any other documents you open will not affect your pinned tabs.
Additional Document Tab:Additionally, Visual Studio 11 provides an option to keep all pinned tabs on a separate row of the tab well.
Simulating the multiple monitor support: In Visual Studio 11 you have the ability to float windows outside the IDE (to different monitors if you want) and dock them together.
Documents Preview:Another interesting new feature is the ability to preview documents. This feature becomes useful when debugging your code, as each file you step through will not be opened in a different tab but in the same one. This is really great feature.
Searchable Add Reference Dialog box: Visual Studio 11 lists all the references in the same place, so you can scroll through, search and select the ones you will use or have previously added. Additionally, references are now added asynchronously so the development environment remains responsive.
Improved responsiveness:Visual Studio 11 has improved responsiveness, particularly around long-running operations, memory utilization and features that take full advantage of your computer’s hardware. You can work on your project and interact with the environment while a build is running.It will be really helpful in large project where builds took very long time

Metro Style App (UI Enhancement)

with this release of framework and VS2011microsoft releases development support of new UI pattern called Metro Style App.Know more about metro style check out this blog post

Programming Enhancement

Task-Based Asynchronous Pattern (TAP) (New)

it is major addition to language capabilities in 4.5.Microsoft .NET Framework 4.5 introduces new language features in C# and Visual Basic to provide a new foundation for asynchrony in .NET programming. This new foundation makes asynchronous programming very similar to synchronous programming.
This feature will be a great enhancement to build responsive application without changing your tradition programming style.

New Keyword async and await (New)

The async keyword is one of the new keywords that .NET Framework 4.5 provides. The Async keyword communicates to the compiler that the current method will contain asynchronous code.

Caller Information (New)

: It allow to pass caller function`s such as file name.There are three types of caller info can be passed to called function We could get the below information of caller method :

CallerFilePathAttribute Full path of the source
file that contains the caller. This is the file path at compile time.
CallerLineNumberAttribute Line number in the
source file at which the method is called.
CallerMemberNameAttribute Method or property
name of the caller.

Run time Enhancement

The following features and improvements were added to the common language runtime and to .NET Framework classes:

Timeout for RegEx Evaluation: Ability to limit how long the regular expression engine will attempt to resolve a regular expression before it times out.
Culture Per app domain Ability to define the culture for an application domain.
Console support for Unicode (UTF-16) encoding.
Support for versioning of cultural string ordering and comparison data.
Better performance when retrieving resources.
Zip compression improvements to reduce the size of a compressed file.
Ability to customize a reflection context to override default reflection behavior through the CustomReflectionContext class.

Managed Extensibility Framework (MEF) Enhancement

The Managed Extensibility Framework (MEF) provides the following new features:

Support for generic types.
Convention-based programming model that enables you to create parts based on naming conventions rather than attributes.
Multiple scopes.

Asynchronous I/O (New)

Whole new family of Async file operations are added to I/O classes to facilitate TAP. Asynchronous operations enable you to perform resource-intensive I/O operations without blocking the main thread. This performance consideration is particularly important in a Windows Metro style app or desktop app where a time-consuming stream operation can block the UI thread and make your app appear as if it is not working.

Example of such operations are ReadAsync, WriteAsync, CopyToAsync, FlushAsync, ReadLineAsync, and ReadToEndAsync. Earlier versions such as BeginRead and EndRead are still available in the .NET Framework 4.5 Beta to support legacy code.

Parallel Computing Enhancement

TODO :http://blogs.msdn.com/b/pfxteam/archive/2011/09/17/10212961.aspx

ASP.Net Enhancement

ASP.NET 4.5 Developer Preview includes the following new features:

HTML5 Support for new HTML5 form types.
Model binders: Support for model binders in Web Forms. These let you bind data controls directly to data-access methods, and automatically convert user input to and from .NET Framework data types.
Unobtrusive JavaScript : Support for unobtrusive JavaScript in client-side validation scripts.
Improved handling of client script through bundling and minification for improved page performance.
Integrated encoding routines from the AntiXSS library (previously an external library) to protect from cross-site scripting attacks.
WebSockets : Support for WebSockets protocol.
Asynchronously HTTP :Support for reading and writing HTTP requests and responses asynchronously.
Support for asynchronous modules and handlers.
Support for content distribution network (CDN) fallback in the ScriptManager control.

For more information about these features, see What’s New for ASP.NET 4.5 and Web Development in Visual Studio 11 Developer Preview.

New Features in ASP.NET MVC 4 Beta

Networking

System.Net.Http
System.Net.Http.Headers
RFC-compliant URI support. For more information, see Uri and related classes.
Support for Internationalized Domain Name (IDN) parsing. For more information, see Uri and related classes.
Support for Email Address Internationalization (EAI). For more information, see the System.Net.Mail namespace.
Improved IPv6 support. For more information, see the System.Net.NetworkInformation namespace.
Dual-mode socket support. For more information, see the Socket and TcpListener classes.

Windows Presentation Foundation (WPF)

In the .NET Framework 4.5 Developer Preview, Windows Presentation Foundation (WPF) contains changes and improvements in the following areas:

· The new Ribbon control, which enables you to implement a ribbon user interface that hosts a Quick Access Toolbar, Application Menu, and tabs.
· The new INotifyDataErrorInfo interface, which supports synchronous and asynchronous data validation.
· New features for the VirtualizingPanel and Dispatcher classes.
· Improved performance when displaying large sets of grouped data, and by accessing collections on non-UI threads.
· Data binding to static properties, data binding to custom types that implement the ICustomTypeProvider interface, and retrieval of data binding information from a binding expression.
· Repositioning of data as the values change (live shaping).
· Better integration between WPF and Win32 user interface components.
· Ability to check whether the data context for an item container is disconnected.
· Ability to set the amount of time that should elapse between property changes and data source updates.
· Improved support for implementing weak event patterns. Also, events can now accept markup extensions.

For more information, see What's New in WPF Version 4.5 Developer Preview.

Windows Communication Foundation (WCF)

In the .NET Framework 4.5 Developer Preview, the following features have been added to make it simpler to write and maintain Windows Communication Foundation (WCF) applications:

· Simplification of generated configuration files.
· Support for contract-first development.
· Ability to configure ASP.NET compatibility mode more easily.
· Changes in default transport property values to reduce the likelihood that you will have to set them.
· Updates to the XmlDictionaryReaderQuotas class to reduce the likelihood that you will have to manually configure quotas for XML dictionary readers.
· Validation of WCF configuration files by Visual Studio as part of the build process, so you can detect configuration errors before you run your application.
· New asynchronous streaming support.
· New HTTPS protocol mapping to make it easier to expose an endpoint over HTTPS with Internet Information Services (IIS).
· Ability to generate metadata in a single WSDL document by appending ?singleWSDL to the service URL.
· Websockets support to enable true bidirectional communication over ports 80 and 443 with performance characteristics similar to the TCP transport.
· Support for configuring services in code.
· XML Editor tooltips.
· ChannelFactory caching support.
· Binary encoder compression support.

For more information, see What's New in Windows Communication Foundation.

Windows Workflow Foundation (WF)

Several new features have been added to Windows Workflow Foundation (WF) in the .NET Framework 4.5 Developer Preview. These new features include:

· Ability to create state machine workflows.

· Enhanced Workflow Designer features such as the following:

· Enhanced workflow search capabilities in Visual Studio, including Quick Find and Find in Files.
· Ability to automatically create a Sequence activity when a second child activity is added to a container activity, and to include both activities in the Sequence activity.
· Panning support, which enables the visible portion of a workflow to be changed without using the scroll bars.
· A new Document Outline view that shows the components of a workflow in a tree-style outline view and lets you select a component in the Document Outline view.
· Ability to add annotations to activities.
· Ability to define and consume activity delegates by using the workflow designer.
· Auto-connect and auto-insert for activities and transitions in state machine and flowchart workflows.

· Storage of the view state information for a workflow in a single element in the XAML file, so you can easily locate and edit the view state information.
· A NoPersistScope container activity to prevent child activities from persisting.

· Support for C# expressions:

· Workflow projects that use Visual Basic will use Visual Basic expressions, and C# workflow projects will use C# expressions.
· C# workflow projects that were created in Visual Studio 2010 and that have Visual Basic expressions are compatible with C# workflow projects that use C# expressions.
· Versioning enhancements:
· The new WorkflowIdentity class, which provides a mapping between a persisted workflow instance and its workflow definition.
· Side-by-side execution of multiple workflow versions in the same host, including WorkflowServiceHost.
· In Dynamic Update, the ability to modify the definition of a persisted workflow instance.
· Contract-first workflow service development, which provides support for automatically generating activities to match an existing service contract.