What is new in .NET 4.5

Consolidated list of New Features in .NET 4.5 grouped by Category.

.NET 4.5 is an IN-PLACE upgrade and it comes pre-installed with Windows 8 and Windows Server 8.

Base Class Libraries (BCL)

  • Async support
    • Key Interfaces now support async
  • Improvements to
    • Networking (IPV6 enchanced, IDN, EAI)
    • WeakReferences
    • ArraySegment
    • Streams
    • ReadOnlyDictionary
    • Compression
    • CLR objects over 2GB in size
    • Resource file management performance
    • Unicode (v6, console support)
    • Task Parallel Library
      • Task thread controls Improved
        • Task.WaitAll
        • Task.WaitAny
    • TPL Dataflow
      • Tools for Parallel data flow processing

C# 5.0

  • Support for async programming
    • async and await keywords
    • Methods can access call site info as parameters (CallerInfo)


  • Support for Contract-First Development.
  • Support for flat single WSDL file
  • WebSocket support for WCF based Services (Only with Windows 8)
  •  New Bindings: NetHttpBinding and NetHttpsBinding
  • New Channels (UDP Binding (fire and forget), Websockets)
  • Multiple authorization models for HTTP endpoints
  • New simple HttpClient Class
  • Streaming Improvements.
  • Configuration improvements:
  • Tooltips , Intellisense and compile-time validation in config files
  • Generated client config files cleaned up – Only non-default binding configuration will be generated


  • Workflow Versioning
    • Basic building blocks for versioning provided by WorkflowIdentity
    • Host several versions of a service side by side
    • Update running instances to a new definition using DynamicUpdate
  • Authoring Improvements
    • Contract First Services
      • Create workflow service based on an existing contract
    • C# Expressions
    • Better experience with State Machine/Flowchart designer featuring Auto-connect, Auto-insert and Panning
  • Faster execution
  • State machines
  • Runtime
    • Improved Performance
    • Run workflows in Partial Trust
    • Expressions Extensibility – Ability to plug custom expressions.
  • Designer Improvements
    • Search
    • Performance
    • Usability
    • Better Integration with VS


  • Built-in Ribbon controls
  • Databinding Improvements.
  • Ability to add breakpoints to databindings.
  • Datasource change aware views
  • Improved performance when displaying large amount of data
  • MVVM Improvements
  • Validation Improvements
  • Dispatcher Improvements
  • Designer improvements: VS11 has the same design engine as Expression Blend
  • http://msdn.microsoft.com/en-us/library/bb613588(v=vs.110).aspx


Example : TextMode property of the TextBox control support new HTML 5 input types like email, datetime

  • Multiple support for FileUpload Control
  • Validator and UpdatePanel now support for new HTML5 elements
  • Performance
    • Performance Improvement for ASP.NET Web Hosting
      • Faster ASP.NET Startup (multi-core JIT compilation, sharing common assemblies)
      • Reduced memory footprint (tuning of GC with 1 single setting)
    • Up to 35% performance in combination with Windows 8 Server (prefetching feature)
    • http://www.asp.net/vnext/overview/whitepapers/whats-new#_Toc_perf


  • Support for Generic parts
  • Support for binding POCOs. Attribute requirements removed.
  • Explicit and convention based binding between objects.
  • MEF problems are easy to diagnose
    • Break on First Chance Exceptions
    • Visualize the exception

Entity Framework 4.5 Features

  • Enums
  • Spatial Data
  • Table-Valued Functions
  • Sprocs with multiple result sets
  • Automatic compiled LINQ queries
  • Query optimization improvements
  • Multiple Diagram Support
  • Database Project integration

Visual Studio 11 Improvements for web developers