Introduction to ASP.NET Kevin McManus Adapted from material by Gill Windall and Mark Sapossnek.

Introduction to ASP.NET

Kevin McManus Adapted from material by Gill Windall and Mark Sapossnek

© K.M. 2/11/2007 the University of Greenwich 2


Contents• An overview of what .NET is and some of its key

features• Describe the areas of .NET likely to have an

impact on how web applications are developed• What is Microsoft .NET?

• Some views• Web Services• ASP .NET versus ASP• .NET Platform and .NET Framework• Common Language Runtime (CLR)



What is Microsoft .NET? that new language C#

Microsoft putting XML into everything

the next version of Visual Basic the next version of ASP

the next version of Visual Studio

Microsoft trying to kill Java

being able to run everything across the Net

it’s a good thing

it’s rubbish!!!



What is Microsoft .NET?• Initially announced as the latest release of everything

Microsoft• ASP.NET, VB.NET, VisualStudio.NET

• With are some big changes• the new language C#

• got rid of VB at last • the Common Language Runtime (CLR)

• language integration - shared libraries• possible platform independence – Mono CLR• an attack on JRE

• ability to develop and use software components over the web• XML based Web Services

• simplified deployment of Windoze software• an end to DLL hell

• no use of the “registry”• http://zdnet.com.com/2100-1104-991369.html

• no more mixing HTML and script code in ASP



Web Services • Allow remote access to software components

• via standard web protocols

• Use XML to exchange structured data• Microsoft .NET is just one implementation of Web

Services but there are many others• The idea of Web Services is not exclusive to Microsoft

“Last Wednesday, Microsoft released a new software development program called Visual Studio.Net. …. it represents the company's big leap into Web services, which many hope will trigger the next generation of corporate computing innovation. Microsoft spent $2 billion developing Visual Studio.Net and C#, but just about every other technology company on the planet -- including IBM and Sun Microsystems -- is also placing big bets on Web services.”

ZDNet Feb 2002



Web Services and Microsoft .NET

There are three main angles on this:

1. Microsoft plans to provide a number of Web Services that application developers can use for a fee• Microsoft .NET Passport - authentication service offers single

sign-on capability for any Web site• now Windows Live ID

• Microsoft .NET My Services - set of user-centric, XML Web services to manage, protect personal information e.g. Calendar, Contact, Inbox

2. Using ASP.NET you can create Web Services that others can use

3. Using a .NET language (or ASP.NET) you can write a program that uses Web Services



Programming the WebServer-Side Code

• What is server-side code?• Software that runs on the server, not the client• Receives input from

• URL parameters• HTML form data• Cookies• HTTP headers

• Can access server-side databases, e-mail servers, files, mainframes, etc.

• Dynamically builds a custom HTML response for a client



Programming the WebServer-Side Code

• Why server-side code?• Availability

• You can reach the Internet from any browser, any device, any time, anywhere

• Manageability• Does not require distribution of application code• Easy to change code

• Security• Source code is not exposed• Once user is authenticated, can only allow certain actions

• Scalability• Web-based 3-tier architecture can scale out



Programming the WebServer-Side Technologies

• Common Gateway Interface (CGI)• not language specific

• Internet Server API (ISAPI)• Netscape Server API (NSAPI)

• Active Server Pages (ASP)• now obsolete

• Java Server Pages (JSP)• PHP Hypertext Processor (PHP)• Cold Fusion (CFM)

• actually J2EE with the arrival of ColdFusion MX• ASP.NET



Programming the Web Active Server Pages (ASP)

• Technology to easily create server-side applications

• ASP pages are written in a scripting language• usually VBScript but also Jscript or PerlScript

• An ASP page contains static HTML interspersed with server-side code

• ASP script is commonly used to access and update a database• 3-tier systems



Programming the WebASP

HTTP request(form data, HTTP

header data)

HTTP responseHTML, XML

ASP page(static HTML +

server-side logic)



Introduction to .NETWhat is .NET?

• A vision• web sites will be joined by web services• new smart devices will join the PC• user interfaces will become more adaptable

and customizable• enabled by web standards



• A platform• the .NET Framework• Visual Studio.NET• .NET Enterprise Servers

• database, messaging, integration, commerce, proxy, security, mobility, orchestration, content management

• .NET Building Block Services• Passport• .NET My Services (“Hailstorm”)

• goal: make it incredibly easy to build powerful web applications and web services


} The focus of this course



• A business model• software as a service• subscription-based services• application hosting




Introduction to .NETThe .NET Platform

Web Form

.NET Framework

Windows and Linux and…

Web Service

.NET FoundationWeb Services

Your InternalWeb Service

Third-PartyWeb Services

.NET EnterpriseServers

Clients Applications

Protocols: HTTP,HTML, XML, SOAP, UDDI

Tools:Visual Studio.NET,

Notepad



The Microsoft .NET Platform

Visual Studio .NET

.NET Enterprise Servers

SQL Server 2005Win Server 2003

.NET Framework

CLR, C#, ASP.NET, etc.

.NET Services

e.g. Microsoft Passport

Operating System e.g. Windows XP, Windows 2000, Linux



Web Services

• A programmable application component accessible via standard web protocols

• The centre of the .NET architecture

• Exposes functionality over the Web

• Built on existing and emerging standards• HTTP, XML, SOAP, UDDI, WSDL, …



Web ServicesEvolution of the Web

Generation 2Web Applications

HTML

Generation 1Static HTML

HTML

HTML, XML

Generation 3Web Services

XML



• A set of technologies for developing and using components to create:• web forms• web services• windows applications

• Supports the software lifecycle• development• debugging• deployment • maintenance

The .NET FrameworkWhat Is the .NET Framework?



The Microsoft .NET Framework

XML based Web Services

Web Forms ASP.NET Windows

Forms

Library classes for accessing data and XML(ADO.NET, SQL, XML, XSLT)

Library Framework Base classes(IO, string, collections, security)

Common Language Runtime



Common Language Specification


VB C++ C#

ASP.NET: Web Servicesand Web Forms

JScript …

WindowsForms

.NET Framework Base Classes

ADO.NET: Data and XML

Visu

al Stu

dio

.NE

T

The .NET FrameworkThe .NET Framework and Visual Studio.NET



System.Data

DesignOLEDB

SQLTypesSQL

System

GlobalizationDiagnostics

ConfigurationCollections

ResourcesReflection

NetIO

ThreadingText

ServiceProcessSecurity Runtime

InteropServicesRemotingSerialization

System.Xml

XPathXSLT Serialization

System.Web

Configuration SessionStateCaching Security

ServicesDescriptionDiscoveryProtocols

UIHtmlControls

WebControlsSystem.Drawing

ImagingDrawing2D

TextPrinting

The .NET Framework.NET Framework Classes

System.Windows.FormsForm Button

MessageBox ListControl



Common Language RuntimeGoals

• Development services• deep cross-language interoperability• increased productivity

• Deployment services• simple, reliable deployment• fewer versioning problems – NO MORE ‘DLL HELL’

• Run-time services• performance • scalability • availability

• reliability• security• safety



Common Language Runtime• Programs can run on any platform for which the CLR has been

implemented• just like the JVM

• The CLR is no longer only available for Microsoft operating systems• there are initiatives to port to other platforms• Mono on Linux released 24th Nov 2004

• There are many .NET languages• Microsoft

• C# , C++, VB.NET, JScript

• Third Party• Cobol, Fortran, Perl, Python, Smalltalk

• CLR gives language integration• a class written in one language can be used by a class written in

another• share exactly the same libraries• one API to learn



Source CodeSource Code

C++, C#, VB or any .NET language

csc.exe or vbc.exe

Compiler

AssemblyAssembly

DLL or EXE

Common Language RuntimeCompilation




Program written in any .NET supported language

C#, VB.NET, etc.

Intermediate Language (IL) - like Java bytecode

(.exe or .dll)

compile


Loads and executes code, garbage collects etc



• Assembly• logical unit of deployment• contains manifest, metadata, MSIL and resources

• Manifest• metadata about the components in an assembly

(version, types, dependencies, etc.)

• Type metadata• completely describes all types defined in

an assembly: properties, methods, arguments, return values, attributes, base classes, …

Common Language RuntimeAssemblies



Common Language RuntimeAssemblies

• Microsoft Intermediate Language• MSIL or IL• all languages compile to IL (managed code)• IL is always compiled to native code before

being executed• Just In Time (JIT) compilation

• Resources• data, images, audio, etc.



Common Language RuntimeExecution Model

CLR

VBSource code

Compiler

C++C#

Assembly AssemblyAssembly

Operating System Services

MSIL

Common Language Runtime JIT Compiler

Compiler Compiler

Nativecode

ManagedCode

ManagedCode

ManagedCode

UnmanagedCode

CLR Services

Ngen



Common Language RuntimeServices

• Code management• Conversion of MSIL to

native code • Loading and execution of

managed code • Creation and

management of metadata• Verification of type safety• Insertion and execution of

security checks• Memory management

and isolation

• Garbage collection• Handling exceptions

across languages• Interoperation

between .NET Framework objects, COM objects and Win32 DLLs

• Automation of object layout for late binding

• Developer services (profiling, debugging, etc.)



• Common Type System (CTS)• superset of the data types used by most modern programming

languages

• Common Language Specification (CLS)• subset of CTS that allows code written in different languages to

interoperate

• What languages?• Microsoft - C#, C++, VB.NET, Jscript• third party

• Perl, Ada, Cobol, Java, Fortran, Delphi• Eiffel, Smalltalk, Scheme, Oberon, Haskell, Python,…• only practical if the language supports some sort of encapsulation

Common Language RuntimeMultiple Language Support



Common Language RuntimeApplications

• An application consists of one or more assemblies• How does one assembly bind to another?

• based upon metadata and policy• local (preferred)• Assembly Global Cache (AGC) (accurate garbage collection?)

• Multiple versions of an assembly may exist on the same machine• easier software deployment, updates and removal• multiple versions of an assembly can even be used by

the same application• like this is a new thing?



Common Language RuntimeSecurity

• Evidence-based security (authentication)

• Based on user identity and code identity

• Configurable policies

• Imperative and declarative interfaces



Windows Forms

• Framework for building rich clients

• Built upon .NET Framework, languages

• Rapid Application Development (RAD)

• Visual inheritance• Anchoring and docking• Rich set of controls

• Extensible controls• Data-aware• Easily hooked into

Web Services• ActiveX support• Licensing support• Printing support• Advanced graphics



Web Forms

• Built with ASP.NET• logical evolution of ASP• similar development model: edit the page and go

• Requires less code• actually more code but less programming

• New programming model• event-driven/server-side controls• rich controls (e.g. data grid, validation)• data binding• controls generate browser-specific code• simplified handling of page state



Web Forms

• Allows separation of UI and business logic• separation of concerns is a good thing

• cleaner, more maintainable code• no more VB

• Uses .NET languages• not just scripting

• Easy to use components

• XCOPY/FTP deployment

• Simple configuration (XML-based)



Web Forms

• Caching (pages, fragments, custom)

• Scalable session state management

• Tracing support

• ASP.NET is extensible• no ISAPI / ASP dichotomy

• Automatic process rollover

• Forms-based authentication



• Similar to ADO, but better factored• Language-neutral data access• Supports two styles of data access

• disconnected• forward-only, read-only access

• Supports data binding• DataSet: a collection of tables• Can view and process data relationally (tables) or

hierarchically (XML)

ADO.NETActiveX Data Objects



Languages C#

• New language created for .NET• a Java rip-off

• Safe, productive evolution of C++• but not as safe as Java until M$ sort out the

exceptions• Key concepts:

• component-oriented• everything is an object• robust and durable code• preserving your investment

• whatever that means

• Submitted to the ECMA for standardization



Languages Visual Basic.NET

• Modernizes and simplifies Visual Basic• because the old VB was pants

• Now provides• inheritance• threading• exception handling• Support for late binding

• whatever that is

• Actually just C# with a different syntax• almost



Conclusion

• dotNET is pretty neat really• even if it does come from M$

• A whole lot of good ideas have been gathered together without the accumulation of legacy bugware is observed in other M$ products

• Although .NET initially looked like another attempt by Mr Evil to take over the world it is remarkably open and standard compliant compared with other M$ offerings

• The best bit is probably Visual Studio with it’s tooled up approach to application development



More Resources

• .NET• http://www.microsoft.com/net/• http://msdn.microsoft.com/net/• http://www.gotdotnet.com• msnews.microsoft.com news server

• microsoft.public.dotnet.general newsgroup

• XML• http://msdn.microsoft.com/xml/default.asp• http://www.w3.org/XML/

Introduction to ASP.NET Kevin McManus Adapted from material by Gill Windall and Mark Sapossnek.

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