Asp.Net File Types

Web site applications can contain a number of file types, some supported and managed by ASP.NET, and others supported and managed by the IIS server.

File types are mapped to applications using application mappings. For example, if you use double-click a .txt file in Windows Explorer, Notepad will probably open, because in Windows, .txt file types are mapped by default to Notepad.exe. In Web applications, file types are mapped to application extensions in IIS. 

File Types Managed by ASP.NET

File types that are managed by ASP.NET are mapped to the Aspnet_isapi.dll in IIS.

.asax    Typically a Global.asax file that contains code that derives from the HttpApplication class. This file      represents the application and contains optional methods that run at the start or end of the application lifetime.

.ascx    A Web user control file that defines a custom, reusable control.

.ashx   A generic handler file that contains code that implements the IHttpHandler interface.

.asmx  An XML Web services file that contains classes and methods that are available to other Web applications      by way of SOAP.

.aspx      An ASP.NET Web forms file (page) that can contain Web controls and presentation and business logic.

.axd         A handler file used to manage Web site administration requests, typically Trace.axd.

.browser A browser definition file used to identify the features of client browsers.

.cd     A class diagram file.

.compile A precompiled stub file that points to an assembly representing a compiled Web site file. Executable file types (.aspx, ascx, .master, theme files) are precompiled and put in the Bin subdirectory.

.config A configuration file (typically Web.config) containing XML elements that represent settings for ASP.NET features.

.cs, .jsl, .vb  Class source-code file that is compiled at run time. The class can be an HTTP module, an HTTP handler, a code-behind file for an ASP.NET page, or a stand-alone class file containing application logic.

.csproj, .vbproj, vjsproj   A project file for a Visual Studio client-application project.

.disco, .vsdisco      An XML Web services discovery file used to help locate available Web services.

.dsdgm, .dsprototype   A distributed service diagram (DSD) file that can be added to any Visual Studio solution that provides or consumes Web services to reverse-engineer an architectural view of the Web service interactions.

.dll       A compiled class library file (assembly). Note that instead of placing compiled assemblies in the Bin subdirectory, you can put source code for classes in the App_Code subdirectory.

.licx, .webinfo  A license file. Licensing allows control authors to help protect intellectual property by checking that a user is authorized to use the control.

.master         A master page that defines the layout for other Web pages in the application.

.mdb, .ldb       An Access database file.

.mdf        SQL database file for use with SQL Server Express.

.msgx, .svc  An Indigo Messaging Framework (MFx) service file.

.resources, .resx  A resource file that contains resource strings that refer to images, localizable text, or other data.

.sdm, .sdmDocument A system definition model (SDM) file.

.sitemap   A site-map file that contains the structure of the Web site. ASP.NET comes with a default site-map provider that uses site-map files to easily display a navigational control in a Web page.

.skin  A skin file containing property settings to apply to Web controls for consistent formatting.

.sln  A solution file for a Visual Web Developer project.

.soap  A SOAP extension file

File Types Managed by IIS

.asa    Typically a Global.asa file that contains optional methods that run at the start or end of the ASP session or application lifetime.

.asp         An ASP Web page that contains @ directives and script code that uses the ASP built-in objects.

.cdx         A compound index file structure file for Visual FoxPro.

.cer          A certificate file used to authenticate a Web site.

.idc          An Internet Database Connector file mapped to httpodbc.dll.

.shtm, .shtml, .stm    Mapped to ssinc.dll.

Static File Types

IS serves static files only if their file-name extensions are registered in the MIME types list. This list is stored in the MimeMap IIS metabase property for an application. If a file type is mapped to an application extension, it does not need to be included in the MIME types list unless you want the file to be treated like a static file. Typically, ASP.NET source code file types should not be in the MIME types list because that might allow browsers to view the source code.

.css               Style sheet files used to determine the formatting of HTML elements.

.htm, .html     Static Web files written in HTML code.