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The Web Architecture and ASP.NET. Review of the Web (1). It began with HTTP and HTML, which delivers static Web pages to browsers which would render those pages. HTTP Request. Browser. Web Server. HTTP Response (Web page). Review of the Web (2).
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Review of the Web (1) • It began with HTTP and HTML, which delivers static Web pages to browsers which would render those pages HTTP Request Browser Web Server HTTP Response(Web page)
Review of the Web (2) • Scripting languages were created to execute client code within the context of a browser Browser HTTP Request Web Server Client code (JavaScript)(VBScript) HTTP Response(Web page / code)
Review of the Web (3) • Server-side applications were created to execute code and dynamically generate Web pages based on a particular request Web Server Browser HTTP Request Interpret request Client code (script) Generate HTML and script HTTP Response(Web page / code)
Review of the Web (4) • And now we have AJAX / JSON making partial page requests Web Server Browser Interpret request HTTP Request Generate HTML and script HTTP Response(Web page / code) Client code (Silverlight) Client code (script) Execute AJAX Request
The Great Client/Server Debate • Where do we process? • Client or server • What get’s processed where? • And the interaction between client and server • Where does bandwidth fit into this equation? • Where does processing power (and latency) fit into this equation?
And all the Related Technologies • jQuery – yes it works with ASP • AJAX – ASP has some interesting AJAX libraries • We can (AND WILL) write our own handlers for those AJAX requests • Silverlight is a well-used client-side framework part of RIA (http://msdn.microsoft.com/en-us/library/ee707344(v=vs.91).aspx) • Azure?
Current Client Technologies • And what browser (and version) do you use? • Scripting details vary from browser to browser • DOM objects can vary a bit too • HTML5 and CSS3 support varies but is pretty good
Current Server Technologies • Apache • WebSphere (IBM) • Oracle / Sun (doing ASP.NET, CGI and PHP) • Microsoft and IIS • HP and others have offerings • Largely based on Apache • In summary, there are quite a few
ASP.NET (History) • Introduced with the .NET Framework in 2002 • It made Web development look like traditional Windows development • ASP.NET 2.0 introduced in 2005 gave developers enhanced database tools • This included desktop improvements too • MVC was introduced / much more later • ASP.NET 3.0 released with 2008
ASP.NET (History) • ASP.NET 4 released with Visual Studio 2010 and version 4 of the Framework • Razor was introduced along with ASP.NET Web pages • Web pages and Web Forms are different • There is an open-source movement (We will see how this pans out) • Support for HTML 5 and CSS 3 is very good
ASP.NET (History) • Current version is Visual Studio 2013 and Framework version 4.5.1
What is a .NET Application (1)? • It looks and works surprisingly like Java • Source code (VB, C#, etc.) is compiled into a machine independent assembly language (MSIL or IL) • The executable file is called an assembly • IL can be disassembled using the IL Disassembler (ILDASM)
What is a .NET Application (2)? • MSIL is translated into native executable code via the Just-in-Time (JIT) compiler • It’s possible to precompile an application using the Native Image Generator (Ngen) • All .NET applications run under the control of the Common Language Runtime (CLR) • We call this managed code
What is a .NET Application (3)? • On the desktop, the application runs under the control of the Common Language Runtime • With Respect to Web applications, all execution is handled on the server (IIS) • http://msdn.microsoft.com/en-us/library/bb470252.aspx
The ASP.NET Runtime • When IIS sees an .aspx file, it loads aspnet_isapi.dll to create the Page object • Application behavior is controlled by configuration files • Machine.config is the global machine configuration file • Web.config allows you to override default configuration items • Both are XML documents
Programming ASP.NET • Conceptually it’s much like the VB programming you are used to • You create procedures in event handlers and general procedures • You declare variables • Instead of a form, the primary user interface is the WebForm
Current ASP Technologies • ASP Web Forms • Have been around for a while and have continued to evolve • ASP.NET MVC • It stands for Model-View-Controller • It’s an alternative to Web Forms • ASP.NET Web Pages (Razor) • A more lightweight processing model • Looks a bit like PHP • Silverlight and RIA
ASP.NET Web Forms • Provides server-side tools for site navigation • Menus, Drill-down toolbars, breadcrumbs, etc. • Authentication tools • Database connections • Client and server executable code • State management and caching • Authentication and role management • Deployment tools • Robust development tools (Visual Studio)
ASP.NET Web Forms (Introduction) HTTP Server (IIS) ASP Worker Client (browser) Process request request Generate client page (HTML) response
Web Forms and Stateful Web Programming • Remember that the Web is stateless • Web servers to not persist state from one request to the next • ASP.NET does allow stateful programming though • various hidden fields and serialized data • server side session objects • Much more on state management later
Web Forms and Event-Driven programming • ASP.NET, though serialization, simulates event-driven programming • ASP.NET events differ significantly from Windows Forms events
Introduction to the Web Forms Component Model • Remember that .NET is an OOP environment and ASP.NET is no exception • As the developer, you create .aspx pages that make up a Web application • When executed, the .aspx page is compiled into a custom class that inherits from System.Web.UI.Page • As the developer, you can program against this class just as you would program against any class • It all happens on the server!
ASP.NET MVC • MVC is the acronym form Model-View-Controller • It’s a design pattern coined by the GOF • It requires version 4 of the .NET Framework • It’s an alternative to traditional ASP.NET Web forms
Web Matrix and Razor • A “lightweight” technology to create simple Web sites • Requires version 4.0 of the .NET Framework and a few add-ins
Silverlight • It run on a client (browser) and communicates with a server via RIA services • Netflix?