What is the difference between WCF and ASMX Web Services?

Basic difference between ASMX or ASP.NET is web service designed to send and receive messages using SOAP over HTTP.

WCF can exchange messages using any format (SOAP is default) over any transport protocol such as HTTP, TCP/IP, MSMQ, NamedPipes etc.

What is the file extension of web services?

.asmx

What namespaces are imported by default in ASMX files?

The following namespaces are imported by default. Other namespaces must be imported manually :
System
System.Collections
System.ComponentModel
System.Data
System.Diagnostics
System.Web
System.Web.Services

Define and describe different File Name Extensions in Asp.net.

Applications written in Asp .net have different files with different extension. Native files generally have .aspx or .ascx extension. File name containing the business logic depend on the language that you are using. For Example c# files have extension aspx.cs.

  • .asax: Default.asax, used for application-level logic
  • .ascx: Web UserControls i.e. custom controls can be placed onto web pages.
  • .ashx: for custom HTTP handlers.
  • .asmx: web service pages that are Code behind page of an asmx file is placed into the app_code folder.
  • .axd: when enabled in web.config requesting trace.axd outputs application-level tracing. It is also used for special webresource.axd handler which allows control or component developers to package a component or control complete with images, script, css etc. for deployment in a single file.
  • .config: web.config is the only file in a Web application. This is the by default extension (machine.config similarly affects the entire Web server and all applications on it). Also ASP.NET facilitates to create and consume other config files. These are stored in XML format.
  • .cs/vb: Code files (cs indicates C#, vb indicates Visual Basic). Code behind files predominantly has the extension “.aspx.cs” or “.aspx.vb” for the two most common languages. Other code files can also exist in the web folders with the cs/vb extension. These are placed inside the App_Code folder where they are dynamically compiled and available to the whole application.
  • .dbml: LINQ to SQL data classes file
  • .master: Master page file
  • .resx: resource files for localization. Resource files can be global (e.g. messages) or “local” which means specific for a single aspx or ascx file.
  • .sitemap: sitemap configuration files. The default file name is web.sitemap.
  • .skin: theme skin files.
  • .svc: Windows Communication Foundation service file.