A web application framework is a software framework that is designed to support the development of dynamic websites, web applications and web services. The framework aims to alleviate the overhead associated with common activities performed in Web development...
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
A programmer, computer programmer or coder is someone who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to...
A web application is an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is coded in a browser-supported language and reliant on a common web browser to render the application executable.Web applications are...
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
s. It was first released in January 2002 with version 1.0 of the .NET Framework
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
Active Server Pages , also known as Classic ASP or ASP Classic, was Microsoft's first server-side script engine for dynamically-generated Web pages. Initially released as an add-on to Internet Information Services via the Windows NT 4.0 Option Pack Active Server Pages (ASP), also known as Classic...
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
(CLR), allowing programmers to write ASP.NET code using any supported .NET language. The ASP.NET SOAP
SOAP
SOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks...
extension framework allows ASP.NET components to process SOAP messages.
Internet Information Services – formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server. IIS 7.5 supports HTTP, HTTPS,...
4.0 in 1997, Microsoft began researching possibilities for a new Web application model that would solve common complaints about ASP, especially with regard to separation of presentation and content
Separation of presentation and content
Separation of presentation and content is a common idiom, a design philosophy, and a methodology applied in the context of various publishing technology disciplines, including information retrieval, template processing, web design, web development, word processing, desktop publishing,...
and being able to write "clean" code. Mark Anders, a manager on the IIS team, and Scott Guthrie
Scott Guthrie
Scott Guthrie is a vice president in the Microsoft Developer Division. He runs the development teams that build ASP.NET, Common Language Runtime , Core .NET Base Class Library, Silverlight, Windows Forms, WPF, Internet Information Services 7.5, Commerce Server, .NET Compact Framework, Visual Web...
, who had joined Microsoft in 1997 after graduating from Duke University
Duke University
Duke University is a private research university located in Durham, North Carolina, United States. Founded by Methodists and Quakers in the present day town of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco industrialist James B...
, were tasked with determining what that model would look like. The initial design was developed over the course of two months by Anders and Guthrie, and Guthrie coded the initial prototypes during the Fall of 1997.
The initial prototype was called "XSP"; Guthrie explained in a 2007 interview that, "People would always ask what the X stood for. At the time it really didn't stand for anything. XML started with that; XSLT
XSLT
XSLT is a declarative, XML-based language used for the transformation of XML documents. The original document is not changed; rather, a new document is created based on the content of an existing one. The new document may be serialized by the processor in standard XML syntax or in another format,...
started with that. Everything cool seemed to start with an X, so that's what we originally named it." The initial prototype of XSP was done using Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...
In computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
and other features that were seen as desirable features that Microsoft's Component Object Model
Component Object Model
Component Object Model is a binary-interface standard for software componentry introduced by Microsoft in 1993. It is used to enable interprocess communication and dynamic object creation in a large range of programming languages...
platform did not support. Guthrie described this decision as a "huge risk", as the success of their new Web development platform would be tied to the success of the CLR, which, like XSP, was still in the early stages of development, so much so that the XSP team was the first team at Microsoft to target the CLR.
With the move to the Common Language Runtime, XSP was re-implemented in C# (known internally as "Project Cool" but kept secret from the public), and the name changed to ASP+, as by this point the new platform was seen as being the successor to Active Server Pages
Active Server Pages
Active Server Pages , also known as Classic ASP or ASP Classic, was Microsoft's first server-side script engine for dynamically-generated Web pages. Initially released as an add-on to Internet Information Services via the Windows NT 4.0 Option Pack Active Server Pages (ASP), also known as Classic...
, and the intention was to provide an easy migration path for ASP developers.
Mark Anders first demonstrated ASP+ at the ASP Connections conference in Phoenix, Arizona
Phoenix, Arizona
Phoenix is the capital, and largest city, of the U.S. state of Arizona, as well as the sixth most populated city in the United States. Phoenix is home to 1,445,632 people according to the official 2010 U.S. Census Bureau data...
on May 2, 2000. Demonstrations to the wide public and initial beta release of ASP+ (and the rest of the .NET Framework) came at the 2000 Professional Developers Conference
Professional Developers Conference
Microsoft's Professional Developers Conference is a conference for software developers, normally Windows developers.It covers new and upcoming technology from Microsoft, and so only occurs in the years when there is something new to talk about...
Orlando is a city in the central region of the U.S. state of Florida. It is the county seat of Orange County, and the center of the Greater Orlando metropolitan area. According to the 2010 US Census, the city had a population of 238,300, making Orlando the 79th largest city in the United States...
William Henry "Bill" Gates III is an American business magnate, investor, philanthropist, and author. Gates is the former CEO and current chairman of Microsoft, the software company he founded with Paul Allen...
is a Japanese multinational information technology equipment and services company headquartered in Tokyo, Japan. It is the world's third-largest IT services provider measured by revenues....
demonstrated ASP+ being used in conjunction with COBOL
COBOL
COBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
, and support for a variety of other languages was announced, including Microsoft's new Visual Basic .NET
Visual Basic .NET
Visual Basic .NET , is an object-oriented computer programming language that can be viewed as an evolution of the classic Visual Basic , which is implemented on the .NET Framework...
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
support by way of interoperability tools created by ActiveState
ActiveState
ActiveState is a Canadian software company headquartered in Vancouver, British Columbia. It develops, sells, and supports cross-platform development tools for dynamic languages such as Perl, PHP, Python, Ruby, and Tcl, as well as language distributions and enterprise services...
.
Once the ".NET" branding was decided on in the second half of 2000, it was decided to rename ASP+ to ASP.NET. Mark Anders explained on an appearance on The MSDN Show that year that, "The .NET initiative is really about a number of factors, it's about delivering software as a link building service, it's about XML and Web services and really enhancing the Internet in terms of what it can do ... we really wanted to bring its name more in line with the rest of the platform pieces that make up the .NET framework."
After four years of development, and a series of beta releases in 2000 and 2001, ASP.NET 1.0 was released on January 5, 2002 as part of version 1.0 of the .NET Framework
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
. Even prior to the release, dozens of books had been written about ASP.NET, and Microsoft promoted it heavily as part of its platform for Web services. Guthrie became the product unit manager for ASP.NET, and development continued apace, with version 1.1 being released on April 24, 2003 as a part of Windows Server 2003
Windows Server 2003
Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...
. This release focused on improving ASP.NET's support for mobile devices.
Pages
ASP.NET Web pages, known officially as Web Forms, are the main building block for application development. Web forms are contained in files with an ".aspx" extension; these files typically contain static (X
XHTML
XHTML is a family of XML markup languages that mirror or extend versions of the widely-used Hypertext Markup Language , the language in which web pages are written....
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
markup, as well as markup defining server-side Web Controls and User Controls where the developers place all the required static and dynamic content for the Web page. Additionally, dynamic code which runs on the server can be placed in a page within a block <% -- dynamic code -- %>, which is similar to other Web development technologies such as PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
JavaServer Pages is a Java technology that helps software developers serve dynamically generated web pages based on HTML, XML, or other document types...
Active Server Pages , also known as Classic ASP or ASP Classic, was Microsoft's first server-side script engine for dynamically-generated Web pages. Initially released as an add-on to Internet Information Services via the Windows NT 4.0 Option Pack Active Server Pages (ASP), also known as Classic...
. With ASP.NET Framework 2.0, Microsoft introduced a new code-behind model which allows static text to remain on the .aspx page, while dynamic code remains in an .aspx.vb or .aspx.cs or .aspx.fs file (depending on the programming language used).
Directives
A directive is special instructions on how ASP.NET should process the page. The most common directive is <%@ Page %> which can specify many things, such as which programming language is used for the server-side code.
The above tag is placed at the beginning of the ASPX file. The CodeFile property of the @ Page directive specifies the file (.cs or .vb or .fs) acting as the code-behind while the Inherits property specifies the Class from which the Page is derived. In this example, the @ Page directive is included in SampleCodeBehind.aspx, then SampleCodeBehind.aspx.cs acts as the code-behind for this page:
using System;
namespace Website
{
public partial class SampleCodeBehind : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Response.Write("Hello, world");
}
}
}
Imports System
Namespace Website
Public Partial Class SampleCodeBehind
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
Response.Write("Hello, world")
End Sub
End Class
End Namespace
In this case, the Page_Load method is called every time the ASPX page is requested. The programmer can implement event handlers
Event (computing)
In computing an event is an action that is usually initiated outside the scope of a program and that is handled by a piece of code inside the program. Typically events are handled synchronous with the program flow, that is, the program has one or more dedicated places where events are handled...
at several stages of the page execution process to perform processing.
User controls
User controls are encapsulations of sections of pages which are registered and used as controls in ASP.NET. User controls are created as ASCX markup files. These files usually contain static (X
XHTML
XHTML is a family of XML markup languages that mirror or extend versions of the widely-used Hypertext Markup Language , the language in which web pages are written....
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
markup, as well as markup defining server-side Web controls. These are the locations where the developer can place the required static and dynamic content. A user control is compiled when its containing page is requested and is stored in memory for subsequent requests. User controls have their own events which are handled during the life of ASP.NET requests. An event bubbling mechanism provides the ability to pass an event fired by a user control up to its containing page. Unlike an ASP.NET page, a user control cannot be requested independently; one of its containing pages is requested instead.
Custom controls
Programmers can also build custom controls for ASP.NET applications. Unlike user controls, these controls do not have an ASCX markup file, having all their code compiled into a dynamic link library (DLL)
Dynamic-link library
Dynamic-link library , or DLL, is Microsoft's implementation of the shared library concept in the Microsoft Windows and OS/2 operating systems...
file. Such custom controls can be used across multiple Web applications and Visual Studio
Microsoft Visual Studio
Microsoft Visual Studio is an integrated development environment from Microsoft. It is used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all...
projects.
Rendering technique
ASP.NET uses a visited composites rendering technique. During compilation, the template (.aspx) file is compiled into initialization code which builds a control tree (the composite) representing the original template. Literal text goes into instances of the Literal control class, and server controls are represented by instances of a specific control class. The initialization code is combined with user-written code (usually by the assembly of multiple partial classes) and results in a class specific for the page. The page doubles as the root of the control tree.
Actual requests for the page are processed through a number of steps. First, during the initialization steps, an instance of the page class is created and the initialization code is executed. This produces the initial control tree which is now typically manipulated by the methods of the page in the following steps. As each node in the tree is a control represented as an instance of a class, the code may change the tree structure as well as manipulate the properties/methods of the individual nodes. Finally, during the rendering step a visitor is used to visit every node in the tree, asking each node to render itself using the methods of the visitor. The resulting HTML output is sent to the client.
After the request has been processed, the instance of the page class is discarded and with it the entire control tree. This is a source of confusion among novice ASP.NET programmers who rely on class instance members that are lost with every page request/response cycle.
In computing, a stateless protocol is a communications protocol that treats each request as an independent transaction that is unrelated to any previous request so that the communication consists of independent pairs of requests and responses...
The Hypertext Transfer Protocol is a networking protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web....
protocol. As such, if an application uses stateful interaction, it has to implement state management
State management
State Management refers to the management of the state of one or more user interface controls such as text fields, OK buttons, radio buttons, etc in a Graphical User Interface. In this user interface programming technique, the state of one UI control depends on the state of other UI controls...
on its own. ASP.NET provides various functions for state management. Conceptually, Microsoft treats "state" as GUI
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
state. Problems may arise if an application needs to keep track of "data state"; for example, a finite-state machine which may be in a transient state between requests (lazy evaluation
Lazy evaluation
In programming language theory, lazy evaluation or call-by-need is an evaluation strategy which delays the evaluation of an expression until the value of this is actually required and which also avoids repeated evaluations...
) or which takes a long time to initialize. State management in ASP.NET pages with authentication can make Web scraping
Web scraping
Web scraping is a computer software technique of extracting information from websites...
difficult or impossible.
Application
Application state is held by a collection of shared user-defined variables. These are set and initialized when the Application_OnStart event fires on the loading of the first instance of the application and are available until the last instance exits. Application state variables are accessed using the Applications collection, which provides a wrapper for the application state. Application state variables are identified by name.
Session state
Server-side session state is held by a collection of user-defined session variables that are persistent during a user session. These variables, accessed using the Session collection, are unique to each session instance. The variables can be set to be automatically destroyed after a defined time of inactivity even if the session does not end. Client-side user session is maintained by either a cookie
HTTP cookie
A cookie, also known as an HTTP cookie, web cookie, or browser cookie, is used for an origin website to send state information to a user's browser and for the browser to return the state information to the origin site...
or by encoding the session ID in the URL itself.
ASP.NET supports three modes of persistence for server-side session variables:
In-Process Mode: The session variables are maintained within the ASP.NET process
Process (computing)
In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
. This is the fastest way; however, in this mode the variables are destroyed when the ASP.NET process is recycled or shut down.
ASPState Mode: ASP.NET runs a separate Windows service
Windows Service
On Microsoft Windows operating systems, a Windows service is a long-running executable that performs specific functions and which is designed not to require user intervention. Windows services can be configured to start when the operating system is booted and run in the background as long as...
that maintains the state variables. Because state management happens outside the ASP.NET process, and because the ASP.NET engine accesses data using .NET Remoting, ASPState is slower than In-Process. This mode allows an ASP.NET application to be load-balanced and scaled across multiple servers. Because the state management service runs independently of ASP.NET, the session variables can persist across ASP.NET process shutdowns. However, since session state server runs as one instance, it is still one point of failure for session state. The session-state service cannot be load-balanced, and there are restrictions on types that can be stored in a session variable.
SqlServer Mode: State variables are stored in a database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
, allowing session variables to be persisted across ASP.NET process shutdowns. The main advantage of this mode is that it allows the application to balance load on a server cluster, sharing sessions between servers. This is the slowest method of session state management in ASP.NET.
View state
View state refers to the page-level state management mechanism, utilized by the HTML pages emitted by ASP.NET applications to maintain the state of the Web form controls and widgets. The state of the controls is encoded and sent to the server at every form submission in a hidden field known as __VIEWSTATE. The server sends back the variable so that when the page is re-rendered, the controls render at their last state. At the server side, the application may change the viewstate, if the processing requires a change of state of any control. The states of individual controls are decoded at the server, and are available for use in ASP.NET pages using the ViewState collection.
The main use for this is to preserve form information across postbacks. View state is turned on by default and normally serializes
Serialization
In computer science, in the context of data storage and transmission, serialization is the process of converting a data structure or object state into a format that can be stored and "resurrected" later in the same or another computer environment...
the data in every control on the page regardless of whether it is actually used during a postback. This behavior can (and should) be modified, however, as View state can be disabled on a per-control, per-page, or server-wide basis.
Developers need to be wary of storing sensitive or private information in the View state of a page or control, as the base64
Base64
Base64 is a group of similar encoding schemes that represent binary data in an ASCII string format by translating it into a radix-64 representation...
string containing the view state data can easily be de-serialized. By default, View state does not encrypt the __VIEWSTATE value. Encryption can be enabled on a server-wide (and server-specific) basis, allowing for a certain level of security to be maintained.
Server-side caching
ASP.NET offers a "Cache" object that is shared across the application and can also be used to store various objects. The "Cache" object holds the data only for a specified amount of time and is automatically cleaned after the session time-limit elapses.
Other
Other means of state management that are supported by ASP.NET are cookies
HTTP cookie
A cookie, also known as an HTTP cookie, web cookie, or browser cookie, is used for an origin website to send state information to a user's browser and for the browser to return the state information to the origin site...
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
In World Wide Web, a query string is the part of a Uniform Resource Locator that contains data to be passed to web applications such as CGI programs....
.
Template engine
When first released, ASP.NET lacked a template engine. Because the .NET Framework
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
In object-oriented programming , inheritance is a way to reuse code of existing objects, establish a subtype from an existing object, or both, depending upon programming language support...
, many developers would define a new base class that inherits from "System.Web.UI.Page", write method
Method (computer science)
In object-oriented programming, a method is a subroutine associated with a class. Methods define the behavior to be exhibited by instances of the associated class at program run time...
s there that render HTML, and then make the pages in their application inherit from this new class. While this allows for common elements to be reused across a site, it adds complexity and mixes source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
A markup language is a modern system for annotating a text in a way that is syntactically distinguishable from that text. The idea and terminology evolved from the "marking up" of manuscripts, i.e. the revision instructions by editors, traditionally written with a blue pencil on authors' manuscripts...
. Furthermore, this method can only be visually tested by running the application - not while designing it. Other developers have used include files
Header file
Some programming languages use header files. These files allow programmers to separate certain elements of a program's source code into reusable files. Header files commonly contain forward declarations of classes, subroutines, variables, and other identifiers...
and other tricks to avoid having to implement the same navigation and other elements in every page.
ASP.NET 2.0 introduced the concept of "master pages", which allow for template
Web template
A web template is a tool used to separate content from presentation in web design, and for mass-production of web documents. It is a basic component of a web template system.Web templates can be used to set up any type of website...
-based page development. A Web application can have one or more master pages, which, beginning with ASP.NET 2.0, can be nested. Master templates have place-holder controls, called ContentPlaceHolders to denote where the dynamic content goes, as well as HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
shared across child pages.
Child pages use those ContentPlaceHolder controls, which must be mapped to the place-holder of the master page that the content page is populating. The rest of the page is defined by the shared parts of the master page, much like a mail merge
Mail merge
Mail merge is a software function which allows to create multiple documents from a single template form and a structured data source.-History:This technique of merging data to create gave rise to the term mail merge....
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
controls in the content page must be placed within the ContentPlaceHolder control.
When a request is made for a content page, ASP.NET merges the output of the content page with the output of the master page, and sends the output to the user.
The master page remains fully accessible to the content page. This means that the content page may still manipulate headers, change title, configure caching etc. If the master page exposes public properties or methods (e.g. for setting copyright notices) the content page can use these as well.
Other files
Other file extensions associated with different versions of ASP.NET include:
Extension
Required version
Description
asax
1.0
This is global application file.You can use this file to define global variable(Variable that can be accessed from any Web page in the Web application.) It is mostly used to define the overall application event related to application & session object.Global.asax
Global.asax
The Global.asax file is an optional file used to declare and handle application and session-level events and objects for an ASP.NET web site running on an IIS Web Server. The file contains ASP.NET program code, and is the .NET counterpart of the Global.asa file used for ASP...
ASP.NET HTTP Handlers are a new technique presented in ASP.NET that was not present in the "Classic" ASP. HTTP Handlers are components that implement the System.Web.IHttpHandler interface. Unlike ASP.NET Pages they have no HTML-markup file, no events and other supporting...
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
pages. From version 2.0 a Code behind page of an asmx file is placed into the app_code folder.
Web.config is the main settings and configuration file for an ASP.NET web application. The file is an XML document that defines configuration information regarding the web application....
In software engineering, tracing is a specialized use of logging to record information about a program's execution. This information is typically used by programmers for debugging purposes, and additionally, depending on the type and detail of information contained in a trace log, by experienced...
. Also used for the special webresource.axd handler which allows control/component developers to package a component/control complete with images, script, css etc. for deployment in one file (an 'assembly')
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
format; introduced in version 2.0. ASP.NET 2 includes many of these by default, to support common Web browsers. These specify which browsers have which abilities, so that ASP.NET 2 can automatically customize and optimize its output accordingly. Special .browser files are available for free download to handle, for instance, the W3C Validator, so that it properly shows standards-compliant pages as being standards-compliant. Replaces the harder-to-use BrowserCaps section that was in machine.config and could be overridden in web.config
Web.config
Web.config is the main settings and configuration file for an ASP.NET web application. The file is an XML document that defines configuration information regarding the web application....
Web.config is the main settings and configuration file for an ASP.NET web application. The file is an XML document that defines configuration information regarding the web application....
is the only file in a specific Web application to use this extension by default (machine.config similarly affects the entire Web server and all applications on it), however ASP.NET provides facilities to create and consume other config files. These are stored in XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
format.
cs/vb
1.0
Code files (cs indicates C#, vb indicates Visual Basic, fs indicates F#). Code behind files (see above) predominantly have the extension ".aspx.cs" or ".aspx.vb" for the two most common languages. Other code files (often containing common "library" classes) can also exist in the Web folders with the cs/vb extension. In ASP.NET 2 these should be placed inside the App_Code folder where they are dynamically compiled and available to the whole application.
Razor is an ASP.NET programming syntax used to create dynamic web pages with the C# or Visual Basic programming languages. Razor was in development in June 2010 and was released for Microsoft Visual Studio 2010 in January 2011...
Language Integrated Query is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages, although ports exist for Java, PHP and JavaScript....
ADO.NET Entity Framework is an object-relational mapping framework for the .NET Framework.-Overview:ADO.NET Entity Framework abstracts the relational schema of the data that is stored in a database and presents its conceptual schema to the application...
model
master
2.0
master page file. Default file name is Master1.master
In computing, internationalization and localization are means of adapting computer software to different languages, regional differences and technical requirements of a target market...
. Resource files can be global (e.g. messages) or "local" which means specific for one aspx or ascx file.
sitemap
2.0
sitemap configuration files. Default file name is web.sitemap
The Windows Communication Foundation , previously known as "Indigo", is an application programming interface in the .NET Framework for building connected, service-oriented applications.-The architectures:...
Razor is an ASP.NET programming syntax used to create dynamic web pages with the C# or Visual Basic programming languages. Razor was in development in June 2010 and was released for Microsoft Visual Studio 2010 in January 2011...
)
Directory structure
In general, the ASP.NET directory structure can be determined by the developer's preferences. Apart from a few reserved directory names, the site can span any number of directories. The structure is typically reflected directly in the URLs. Although ASP.NET provides means for intercepting the request at any point during processing, the developer is not forced to funnel requests through a central application or front controller.
The special directory names (from ASP.NET 2.0 on) are:
App_Code : This is the "raw code" directory. The ASP.NET server automatically compiles files (and subdirectories) in this folder into an assembly which is accessible in the code of every page of the site. App_Code will typically be used for data access abstraction code, model code and business code. Also any site-specific http handlers and modules and Web service implementation go in this directory. As an alternative to using App_Code the developer may opt to provide a separate assembly with precompiled code.
App_Data : The App_Data ASP.NET Directory is the default directory for any database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
used by the ASP.NET Website. These databases might include Access (mdb) files or SQL Server
SQL Server
SQL Server may refer to:* Any database server that implements the Structured Query Language* Microsoft SQL Server, a relational database server from Microsoft* Sybase SQL Server, a relational database server developed by Sybase...
(mdf) files. The App_Data is the only directory with Write Access enabled for the ASP.NET web application.:
App_LocalResources : E.g. a file called CheckOut.aspx.fr-FR.resx holds localized resources for the French version of the CheckOut.aspx page. When the UI culture is set to French, ASP.NET will automatically find and use this file for localization.
App_GlobalResources : Holds resx files with localized resources available to every page of the site. This is where the ASP.NET developer will typically store localized messages etc. which are used on more than one page.
App_Themes : Adds a folder that holds files related to themes which is a new ASP.NET feature that helps ensure a consistent appearance throughout a Web site and makes it easier to change the Web site’s appearance when necessary.
App_WebReferences : holds discovery files and WSDL
Web Services Description Language
The Web Services Description Language is an XML-based language that is used for describing the functionality offered by a Web service. A WSDL description of a web service provides a machine-readable description of how the service can be called, what parameters it expects and what data structures...
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
s to be consumed in the site.
Bin : Contains compiled code (.dll files) for controls, components, or other code that you want to reference in your application. Any classes represented by code in the Bin folder are automatically referenced in your application.
Performance
ASP.NET aims for performance benefits over other script-based technologies (including Classic ASP) by compiling the server-side code to one or more DLL file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
Web server can refer to either the hardware or the software that helps to deliver content that can be accessed through the Internet....
. This compilation happens automatically the first time a page is requested (which means the developer need not perform a separate compilation step for pages). This feature provides the ease of development offered by scripting languages with the performance benefits of a compiled binary. However, the compilation might cause a noticeable but short delay to the Web user when the newly-edited page is first requested from the Web server, but will not again unless the page requested is updated further.
Internet Information Services – formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server. IIS 7.5 supports HTTP, HTTPS,...
server (or other compatible ASP.NET servers; see Other implementations, below). The first time a client requests a page, the .NET Framework parses and compiles the file(s) into a .NET assembly and sends the response; subsequent requests are served from the DLL files. By default ASP.NET will compile the entire site in batches of 1000 files upon first request. If the compilation delay is causing problems, the batch size or the compilation strategy may be tweaked.
Developers can also choose to pre-compile their "codebehind" files before deployment, using MS Visual Studio, eliminating the need for just-in-time compilation
Just-in-time compilation
In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...
in a production environment. This also eliminates the need of having the source code on the Web server.
it also supports pre-compile text.
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
has released some extension frameworks that plug into ASP.NET and extend its functionality. Some of them are:
ASP.NET AJAX: An extension with both client-side as well as server-side components for writing ASP.NET pages that incorporate AJAX
Ajax (programming)
Ajax is a group of interrelated web development methods used on the client-side to create asynchronous web applications...
The ASP.NET MVC Framework is a web application framework that implements the model-view-controller pattern. Based on ASP.NET, it allows software developers to build a Web application as a composition of three roles: Model, View and Controller. A model represents the state of a particular aspect of...
: An extension to author ASP.NET pages using the MVC architecture.
ASP.NET compared with ASP classic
ASP.NET simplifies developers' transition from Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
application development to Web development by offering the ability to build pages composed of controls
Widget (computing)
In computer programming, a widget is an element of a graphical user interface that displays an information arrangement changeable by the user, such as a window or a text box. The defining characteristic of a widget is to provide a single interaction point for the direct manipulation of a given...
The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...
. A Web control, such as a button or label, functions in very much the same way as its Windows counterparts: code can assign its properties and respond to its events. Controls know how to render themselves: whereas Windows controls draw themselves to the screen, Web controls produce segments of HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
which form parts of the resulting page sent to the end-user's browser.
ASP.NET encourages the programmer to develop applications using an event-driven
Event-driven programming
In computer programming, event-driven programming or event-based programming is a programming paradigm in which the flow of the program is determined by events—i.e., sensor outputs or user actions or messages from other programs or threads.Event-driven programming can also be defined as an...
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
model, rather than in conventional Web-scripting environments like ASP and PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
. The framework combines existing technologies such as JavaScript with internal components like "ViewState" to bring persistent (inter-request) state to the inherently stateless
Stateless server
In computing, a stateless protocol is a communications protocol that treats each request as an independent transaction that is unrelated to any previous request so that the communication consists of independent pairs of requests and responses...
Active Server Pages , also known as Classic ASP or ASP Classic, was Microsoft's first server-side script engine for dynamically-generated Web pages. Initially released as an add-on to Internet Information Services via the Windows NT 4.0 Option Pack Active Server Pages (ASP), also known as Classic...
are:
Compiled code means applications run faster with more design-time errors trapped at the development stage.
Significantly improved run-time error handling, making use of exception handling
Exception handling
Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of exceptions, special conditions that change the normal flow of program execution....
using try-catch blocks.
Similar metaphors to Microsoft Windows applications such as controls and events.
An extensive set of controls and class libraries allows the rapid building of applications, plus user-defined controls allow commonly-used Web template
Web template
A web template is a tool used to separate content from presentation in web design, and for mass-production of web documents. It is a basic component of a web template system.Web templates can be used to set up any type of website...
, such as menus. Layout of these controls on a page is easier because most of it can be done visually in most editors.
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
, allowing Web pages to be coded in VB.NET, C#, J#, Delphi.NET, Chrome, etc.
Ability to cache the whole page or just parts of it to improve performance.
Ability to use the code-behind development model to separate business logic from presentation.
Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...
A memory leak, in computer science , occurs when a computer program consumes memory but is unable to release it back to the operating system. In object-oriented programming, a memory leak happens when an object is stored in memory but cannot be accessed by the running code...
, the ASP.NET runtime unloads the AppDomain hosting the erring application and reloads the application in a new AppDomain.
Microsoft SQL Server is a relational database server, developed by Microsoft: It is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network...
database or in a separate process running on the same machine as the Web server or on a different machine. That way session values are not lost when the Web server is reset or the ASP.NET worker process is recycled.
Versions of ASP.NET prior to 2.0 were criticized for their lack of standards compliance. The generated HTML and JavaScript sent to the client browser would not always validate against W3C
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web .Founded and headed by Tim Berners-Lee, the consortium is made up of member organizations which maintain full-time staff for the purpose of working together in the development of standards for the...
Ecma International is an international, private non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association changed its name to reflect the organization's global reach and activities...
standards. In addition, the framework's browser detection feature sometimes incorrectly identified Web browsers other than Microsoft's own Internet Explorer
Internet Explorer
Windows Internet Explorer is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year...
as "downlevel" and returned HTML/JavaScript to these clients with some of the features removed, or sometimes crippled or broken. In version 2.0 however, all controls generate valid HTML 4.0, XHTML 1.0 (the default) or XHTML 1.1 output, depending on the site configuration. Detection of standards-compliant Web browsers is more robust and support for Cascading Style Sheets
Cascading Style Sheets
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
is more extensive.
Web Server Controls: these are controls introduced by ASP.NET for providing the UI for the Web form. These controls are state managed controls and are WYSIWYG
WYSIWYG
WYSIWYG is an acronym for What You See Is What You Get. The term is used in computing to describe a system in which content displayed onscreen during editing appears in a form closely corresponding to its appearance when printed or displayed as a finished product...
Internet Information Services – formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server. IIS 7.5 supports HTTP, HTTPS,...
6.0 and lower, pages written using different versions of the ASP framework cannot share Session State without the use of third-party libraries. This criticism does not apply to ASP.NET and ASP applications running side by side on IIS
Internet Information Services
Internet Information Services – formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server. IIS 7.5 supports HTTP, HTTPS,...
7. With IIS 7, modules may be run in an integrated pipeline that allows modules written in any language to be executed for any request.
Development tools
Several available software packages exist for developing ASP.NET applications:
Microsoft Visual Studio is an integrated development environment from Microsoft. It is used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all...
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
Embarcadero Technologies is an American computer software company that develops, manufactures, licenses, and supports a wide range of products and services related to software through its various dynamic product divisions...
HomeSite was an HTML editor owned by Adobe Systems . Unlike WYSIWYG HTML editors such as Microsoft FrontPage and Adobe Dreamweaver, HomeSite was designed for direct editing, or "hand coding," of HTML and other website languages...
Microsoft Expression Web, code-named Quartz, is an HTML editor and general web design software product by Microsoft. It is part of the Expression Studio suite....
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
Microsoft SharePoint Designer is a specialized HTML editor and web design freeware for creating or modifying Microsoft SharePoint sites and web pages. It is a part of Microsoft SharePoint family of products...
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
MonoDevelop is an open source integrated development environment for the Linux platform, Mac OS X, and Microsoft Windows, primarily targeted for the development of software that uses both the Mono and Microsoft .NET frameworks...
Novell, Inc. is a multinational software and services company. It is a wholly owned subsidiary of The Attachmate Group. It specializes in network operating systems, such as Novell NetWare; systems management solutions, such as Novell ZENworks; and collaboration solutions, such as Novell Groupwise...
SharpDevelop is a free and open source integrated development environment for the Microsoft .NET, Mono, Gtk# and Glade# platforms, and supports development in C#, Visual Basic .NET, Boo, F#, IronPython and IronRuby programming languages.It was designed as a free and lightweight alternative to...
Eiffel Software is a software company specializing in object technology, especially tools, training and services for the Eiffel programming language and method, originally introduced by the company in 1985.The company's two flagship products are the EiffelStudio integrated development environment,...
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
Commercial
Frameworks
It is not essential to use the standard Web forms development model when developing with ASP.NET. Noteworthy frameworks designed for the platform include:
The Base One Foundation Component Library is a rapid application development toolkit for building secure, fault-tolerant, database applications on Windows and ASP.NET...
Rapid application development is a software development methodology that uses minimal planning in favor of rapid prototyping. The "planning" of software developed using RAD is interleaved with writing the software itself...
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal...
DotNetNuke is an open source web content management system based on Microsoft .NET technology.DotNetNuke was written in VB.NET, though the developer has shifted to C# since version 6.0. It is distributed under both a Community Edition BSD-style license and commercial proprietary licenses as the...
is an open-source solution which comprises both a Web application framework and a content management system which allows for advanced extensibility through modules, skins, and providers.
MonoRail , a component of the Castle Project, is an open source web application framework built on top of the ASP.NET platform. Inspired by Ruby on Rails Action Pack, MonoRail differs from standard ASP.NET Web Forms development by enforcing separation of concerns using a model-view-controller ...
, an open-source MVC framework with an execution model similar to Ruby on Rails
Ruby on Rails
Ruby on Rails, often shortened to Rails or RoR, is an open source web application framework for the Ruby programming language.-History:...
. The framework is commonly used with Castle ActiveRecord, an ORM layer built on NHibernate
NHibernate
- External links :*** *NuGet...
.
Spring.NET, a port of the Spring framework for Java.
Skaffold.NET, A simple framework for .NET applications, used in enterprise applications.
Survey Project is an open-source Web based survey and form engine framework written in ASP.NET and C#.
Versions
The ASP.NET releases history tightly correlates with the .NET Framework
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
releases:
Date
Version
Remarks
New ASP.NET related features
January 16, 2002
1.0
First version
released together with Visual Studio .NET
Object-oriented Web application development supporting inheritance
Inheritance (computer science)
In object-oriented programming , inheritance is a way to reuse code of existing objects, establish a subtype from an existing object, or both, depending upon programming language support...
Subtype polymorphism, almost universally called just polymorphism in the context of object-oriented programming, is the ability to create a variable, a function, or an object that has more than one form. The word derives from the Greek "πολυμορφισμός" meaning "having multiple forms"...
and other standard OOP features
Developers are no longer forced to use Server.CreateObject(...), so early-binding and type safety are possible.
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
programming; the developer can make use of DLL class libraries and other features of the Web server to build more robust applications that do more than simply rendering HTML (e.g. exception handling
Exception handling
Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of exceptions, special conditions that change the normal flow of program execution....
Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...
Microsoft Visual Studio Express is a set of freeware integrated development environments developed by Microsoft that are lightweight versions of the Microsoft Visual Studio product line. Express Editions were conceived beginning with Visual Studio 2005...
Microsoft SQL Server is a relational database server, developed by Microsoft: It is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network...
New data controls (GridView, FormView, DetailsView)
New technique for declarative data access (SqlDataSource, ObjectDataSource, XmlDataSource controls)
Developed by Microsoft, the Windows Presentation Foundation is a computer-software graphical subsystem for rendering user interfaces in Windows-based applications. WPF, previously known as "Avalon", was initially released as part of .NET Framework 3.0. Rather than relying on the older GDI...
Windows Workflow Foundation is a Microsoft technology that provides an API, an in-process workflow engine, and a rehostable designer to implement long-running processes as workflows within .NET applications...
The Windows Communication Foundation , previously known as "Indigo", is an application programming interface in the .NET Framework for building connected, service-oriented applications.-The architectures:...
Windows CardSpace , is Microsoft's now-canceled client software for the Identity Metasystem. CardSpace is an instance of a class of identity client software called an Identity Selector. CardSpace stores references to users' digital identities for them, presenting them to users as visual...
which uses ASP.NET for login roles.
November 19, 2007
3.5
Released with Visual Studio 2008 and Windows Server 2008
New data controls (ListView, DataPager)
ASP.NET AJAX included as part of the framework
Support for HTTP pipelining and syndication feeds.
Language Integrated Query is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages, although ports exist for Java, PHP and JavaScript....
ASP.NET Dynamic Data is a Ruby on Rails-inspired web application scaffolding framework from Microsoft, shipped as an extension to ASP.NET, that can be used to build data driven web applications. It exposes tables in a database by encoding it in the URI of the ASP.NET web service, and the data in...
Support for controlling browser history in an ASP.NET AJAX application
Ability to combine multiple JavaScript files into one file for more efficient downloading
New namespaces System.Web.Abstractions and System.Web.Routing
April 12, 2010
4.0
Release with Visual Studio 2010>
Parallel extensions and other .NET Framework 4 features
Mono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
Project supports "everything in .NET 4.0 except WPF, EntityFramework and WF, limited WCF." ASP.NET can be run with Mono using one of three options: Apache hosting using the mod_mono module, FastCGI hosting, and XSP.
Further reading
Anne Boehm: Murachs ASP.NET 3.5 Web Programming with VB 2008, July 21, 2008, Mike Murach and Associates, ISBN 978-1-890774-47-9
Stephen Walther: ASP.NET 3.5 Unleashed, December 28, 2007, Sams Publishing, ISBN 0-672-33011-3 ISBN 0-672-33011-3
Stephen Walther: Data Access in the ASP.NET 2.0 Framework (Video Training), September 26, 2007, Sams Publishing, ISBN 0-672-32952-2
