New Features of. Net 4.5

. Net for Metro style app

The Metro style app gives me the feeling that it is used to develop applications with good user experience.ProgramAnd is a desktop-based application.

Http://msdn.microsoft.com/zh-tw/library/windows/apps/hh464920

 

Asynchronous file operations

In. net Framework 4.5 Developer Preview, new asynchronous features were added to the C # and Visual Basic ages. these features Add a task-based model for processing Ming asynchronous operations. to use this new model, use the asynchronous methods in the I/O classes. 

Web

ASP. NET 4.5 Developer Preview templates des the following new features:

• Support for new HTML5 form types.

• 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.

• 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.

• Support for websockets protocol.

  Websocket protocol is a new HTML5 protocol ). It implements full-duplex communication between the browser and the server ).

  Currently, many websites use polling to implement real-time communication ). Round Robin is performed at a specific time interval (such as every 1 second). The browser sends an HTTP request to the server and then the server returns the latest data to the client browser. This traditional HTTP request D mode brings obvious disadvantages-the browser needs to constantly send requests to the server. However, the HTTP request header is very long, the data contained in it may be a small value, which will occupy a lot of bandwidth.

  The most new technology used for polling is comet-Ajax. However, although this technology can reach full-duplex communication, it still needs to send a request (reuqest ).

  In the websocket API, the browser and the server only need to perform a handshake, and then a fast channel is formed between the browser and the server. Data can be directly transmitted to each other. In this websocket protocol, even if the service is implemented, it brings two benefits:

  1. Header

  The Header for mutual communication is very small-about 2 bytes

  2. server push

  The server can send data to the client.

• 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.

  A content delivery network is an environment containing a network of systems. the systems will contain objects, files etc... once a client from UK connects to a CDN, the system near to the UK location will provide data. the same thing will happen for a client from Japan, I. e. system near to Japan will provide data. so this will improve the network bandwidth as clients are getting data from different Systems rather than a centralized mechanic. How this can be used in a developer perspective? Yes, we have Asp.net Ajax with support of CDN.
  By taking advantage of the Microsoft Ajax CDN, You can significantly improve the performance of your Ajax applications. the contents of the Microsoft Ajax CDN are cached on servers located around the world. in addition, the Microsoft Ajax CDN enables browsers to reuse cached JavaScript files for web sites that are located in different domains. in vs2010 we have an attribute for scriptmanager named "enablecdn =" true ". this will make the script libraries to be loaded from CDN. follow this link for more information Http://www.asp.net/ajaxlibrary/cdn.ashx

  The implementation of CDN has high technical requirements. The key technologies used include: server Load balancer technology, dynamic content routing, high-speed cache mechanism, dynamic content distribution and replication, and network security mechanism.

  AD:

  The implementation of CDN has high technical requirements. The key technologies used include: server Load balancer technology, dynamic content routing, high-speed cache mechanism, dynamic content distribution and replication, and network security mechanism.

  Dynamic Content routing:
  When a user accesses a website that joins the CDN service, the domain name resolution request will eventually be handled by the redirection DNS. It provides the Node Address closest to the user through a set of predefined policies (such as content type, geographical region, and network load status, allows users to get quick services. At the same time, it also communicates with all CDN nodes distributed in different locations, collects the health status of each node, and ensures that user requests are not distributed to any unavailable node. It also has the ability to adjust routes in the case of network congestion and failure.

  High-speed cache mechanism:
  The Web Cache service improves the user response time in several ways. Such as proxy cache service, transparent Proxy Cache service, and transparent Proxy Cache service using the redirection service. Through the Web cache service, users can minimize the traffic over the WAN or Internet when accessing webpages. This means that users can get a faster response, and enterprises or ISPs will also benefit from reduced communication costs.

  Dynamic Content Distribution and replication:
  The speed of Website access response depends on many factors, such as the bottleneck of network bandwidth, the congestion and delay of routes during transmission, the processing capability of the website server, and the access distance. In most cases, the website response speed is closely related to the distance between the visitor and the website server. Although telecom carriers are constantly expanding their bandwidth capacity, if the distance between visitors and websites is too long, communication between them must go through heavy route forwarding and processing, and network latency is inevitable. An effective method is to use the content distribution and replication mechanism to distribute most of the static webpages, images, and streaming media data that occupy the website's subjects to acceleration nodes in various regions. The content delivery network can use intelligent routing and traffic management technologies to promptly discover the nearest acceleration node to the visitor and forward the visitor's requests to the acceleration node, which provides content services. By using the content distribution and replication mechanism, the hosting customers do not need to change the original website structure. They only need to modify a small number of DNS configurations to accelerate the network response speed.

  CDN Problems

  CDN is also a new thing abroad, and some IDCs in the United States are also being converted into CDN service providers. Because of this, the biggest difficulty facing CDN is its ignorance or even misleading. CDN is often understood as a icing on the cake rather than a cool service. In fact, for many applications, CDN is a necessary service, such as streaming media service and ASP service. For another example, if an enterprise with branches in various regions carries out a CRM Project, the data traffic may be small, but the response speed is fast. Otherwise, the database content may be disordered. In this case, CDN can also be used. Technically, CDN is difficult to implement because of its high requirements on optical fiber, bandwidth, network equipment, operation and maintenance, and engineering personnel.

For more information about these features, seeWhat's new for ASP. NET 4.5 and web development in Visual Studio 11 Developer Preview. 

Networking

The. NET Framework 4.5 Developer Preview provides a new programming interface for HTTP applications. For more information, see the new system. net. Http andsystem. net. http. headers namespaces.

Also, the following networking improvements are stored in the system. net, system. net. Mail, and related namespaces:

• Improved internationalization and IPv6 support.

• RFC-compliant URI support.

• Support for Internationalized Domain Name (IDN) parsing.

• Support for email address internationalization (EAI ).

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, includingQuick FindAndFind 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 newDocument outlineView that shows the components of a workflow in a tree-style Outline View and lets you select a component inDocument outlineView.

  • 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.

For more information, seeWhat's new in Windows Workflow Foundation. 

 

 

 

See also

Conceptswhat's new in Visual Studio 11 developer previewwhat's new for ASP. net 4.5 and web development in Visual Studio 11 developer previewwhat's new in WPF version 4.5 developer previewwhat's new for Visual Basic in Visual Studio 11 developer previewwhat's new for Visual C # In visual Studio 11 developer previewwhat's new for Visual C ++ in Visual Studio 11 developer previewwhat's new for visual F # in Visual Studio 11 developer previewother resourceswhat's new in Windows communication foundationwhat's new in Windows Workflow Foundation

Original article address:Http://msdn.microsoft.com/zh-cn/library/ms171868 (V = vs.110). aspx