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

2. the University of Greenwich
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)
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3. 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!!!
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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”
no more mixing HTML and script code in ASP
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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
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6. 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
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7. Programming the Web Server-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, servers, files, mainframes, etc.
Dynamically builds a custom HTML response for a client
This course will focus on server-side .NET technologies.
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8. Programming the Web Server-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
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9. Programming the Web Server-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
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10. 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
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11. Programming the Web ASP
HTTP request
(form data, HTTP header data)
HTTP response HTML, XML
ASP page
(static HTML + server-side logic)
An ASP page receives input from a HTTP request, and then dynamically generates a new HTML page that is returned to the client. ASP can also return XML or other types of data.
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12. Introduction to .NET What 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
.NET will enable the next generation of applications.
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13. Introduction to .NET What is .NET?
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
Microsoft is providing a suite of products and services to facilitate building this next generation. This course focuses on the .NET Framework and Visual Studio.NET.
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14. Introduction to .NET What is .NET?
A business model
software as a service
subscription-based services
application hosting
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15. Introduction to .NET The .NET Platform
Clients
Applications
Web Form
Web Service
Protocols: HTTP, HTML, XML, SOAP, UDDI
.NET Framework
Tools: Visual Studio.NET, Notepad
Windows and Linux and…
Each blue box represents a separate computer (or cluster of computers).
Your Internal Web Service
.NET Foundation Web Services
Third-Party Web Services
.NET Enterprise Servers
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16. The Microsoft .NET Platform
Visual Studio .NET
.NET Enterprise Servers
SQL Server 2005
Win Server 2003
.NET Framework
CLR, C#, ASP.NET, etc.
.NET Services
e.g. Microsoft Passport
Operating System e.g. Windows XP, Windows 2000, Linux
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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, …
The definition of a Web service is “a programmable application component accessible via standard Web protocols.” In other words, it is a component that can be called remotely from a client application, over the Internet.
Web Services will allow people, companies, customers, suppliers, doctors, patients, etc. to interact using different computers, different operating systems, and different applications.
For example, you could use the same Web Service to store your personal and work calendar information. You could access this information from different applications and view and change it in different ways.
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18. Web Services Evolution of the Web
HTML, XML
Generation 3 Web Services
XML
Generation 1 Static HTML
HTML
Generation 2 Web Applications
HTML
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19. The .NET Framework What Is the .NET Framework?
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 Framework provides a set of technologies that makes creating, deploying, using and maintaining applications (including Web applications and Web Services) much easier and more robust.
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20. 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
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21. The .NET Framework The .NET Framework and Visual Studio.NETVB
C++ C#
JScript …
Common Language Specification
ASP.NET: Web Services
and Web Forms
Windows Forms
Visual Studio.NET
ADO.NET: Data and XML
The .NET framework exposes numerous classes to the developer. These classes allow the development of rich client applications and Web-based applications alike. The classes are shown here, divided into four areas.
ASP.NET provides the core Web infrastructure, such as Web Forms for UI-based development and Web Services for programmatic interface development.
User interface development on the Windows platform can be done using Windows Forms.
ADO.NET and XML provide the functionality for data access.
The core base classes provide infrastructure services such as security and transaction management.
You can create code in any of a large number of languages. This code will integrate in a deep, seamless manner via a standard called the Common Language Specification.
Visual Studio.NET provides tools that increases your productivity when creating applications.
.NET Framework Base Classes
Common Language Runtime
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22. The .NET Framework .NET Framework Classes
System.Web
System.Windows.Forms
Services UI
Form
Button
Description
HtmlControls
MessageBox
ListControl
Discovery
WebControls
Protocols
System.Drawing
Caching
Security
Drawing2D
Printing
Configuration
SessionState
Imaging
Text
System.Data
System.Xml
OLEDB
SQL
XSLT
Serialization
Design
SQLTypes
XPath
This is but a brief illustration of the breadth of classes provided by the .NET Framework. We will explore many of these classes during this course.
All of these classes are available to ALL languages.
System
Collections IO
Security
Runtime
InteropServices
Configuration
Net
ServiceProcess
Diagnostics
Reflection
Text
Remoting
Serialization
Globalization
Resources
Threading
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23. Common Language Runtime Goals
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
The Common Language Runtime provides the underlying infrastructure for the .NET Framework. It provides very little application-visible functionality itself (security being a notable exception), but provides services to make development, deployment and execution much better in almost every way.
reliability
security
safety
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24. 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
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25. Common Language Runtime Compilation
Source Code
Assembly
Compiler
As a developer you can write code in the language of your choice. Your code is compiled into an Assembly, which is represented as a DLL or EXE.
csc.exe or vbc.exe
C++, C#, VB or any .NET language
DLL or EXE
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26. Common Language Runtime
Program written in any .NET supported language
C#, VB.NET, etc.
compile
Intermediate Language (IL) - like Java bytecode
(.exe or .dll)
Common Language Runtime
Loads and executes code, garbage collects etc
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27. Common Language Runtime Assemblies
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, …
IL is always compiled, never interpreted.
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28. Common Language Runtime Assemblies
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.
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29. Common Language Runtime Execution Model
Source code VB C#
C++
Compiler
Compiler
Compiler
MSIL
Assembly
Assembly
Assembly
Ngen
Common Language Runtime JIT Compiler
When an assembly starts running, the JIT (Just In Time) compiler in the Common Language Runtime converts the IL in the assembly to efficient machine code. It is this code that is actually executed.
Native
code
CLR
Managed
Code
Managed
Code
Managed
Code
Unmanaged
Code
CLR Services
Operating System Services
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30. Common Language Runtime Services
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.)
The CLR provides many sophisticated services.
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31. Common Language Runtime Multiple Language Support
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
The CTS supports many types of data. It allows each language to implement its own unique features.
The CLS allows different languages to interoperate in a deep manner. For example, you can create a class in C# that derives from a class written in Eiffel, and is called from a Perl program.
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32. Common Language Runtime Applications
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?
When we execute an application, how are the required assemblies located? Quite simply; the class loader (part of the CLR) will search the current directory for any assemblies. Assemblies should be kept within the same directory as the application that requires them. This allows different versions of the software to be installed on the machine without interfering with each other. However, if required, it is possible to share an assembly using the global assembly cache.
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33. Common Language Runtime Security
Evidence-based security (authentication)
Based on user identity and code identity
Configurable policies
Imperative and declarative interfaces
Before code in an assembly is run, the CLR looks at the identity of both the user and the code. You can specify policies that determine which code can be executed, and the priviledges that code will have when it runs.
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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
Windows Forms is a framework for building rich Windows client applications, and can be written in any language that supports .NET.
Windows Forms provide the developer with many features, such as:
The simplicity that Visual Basic 6 programmers are used to.
Easy deployment. Windows Forms (as .NET applications) automatically takes advantage of the versioning and deployment features of the .NET Framework.
Windows Forms offers an architecture for controls and control containers based on concrete implementation of the control and container classes. This significantly reduces control-container interoperability issues.
Security. Windows Forms takes full advantage of the security features of .NET. This means that Windows Forms can be used to implement everything from an untrusted control running in the browser to a fully trusted application installed on a user's hard drive.
Web Services Support. Windows Forms offer full support for quickly and easily connecting to Web Services.
Rich Graphics.
Controls. Windows Forms offer a rich set of controls that encompass all of the controls offered by Windows and new features such as new "flat look" styles for Buttons, Radio Buttons and Checkboxes.
Data Awareness. Windows Forms offer full support for the ADO.NET data model.
ActiveX Controls. Windows Forms offer full support for ActiveX controls. You can easily host ActiveX controls in a Windows Forms application. You can also host a Windows Form control as an ActiveX control.
Licensing. Windows Forms take advantage of the .NET Framework enhanced licensing model.
Printing. Windows Forms offer a printing framework that enables applications to provide comprehensive reports.
Accessibility. Windows Form controls implement the interfaces defined by Microsoft Active Accessibility (MSAA), making it straightforward to build applications that support accessibility aids such as screen readers.
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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
The first incarnation of ASP proved very successful. As part of the .NET Framework, Microsoft supports ASP.NET. ASP.NET is a logical evolution of ASP that addresses many of the issues previously associated with ASP.
ASP.NET is now compiled and not interpreted. This of course can go some way towards improving efficiency and also means that code can now support strongly typed variables other than VARIANTS. This makes ASP.NET much more flexible and easier to code.
A great deal of work has also been done to make sure that ASP.NET development has become cleaner and more productive.
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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)
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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
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38. ADO.NET ActiveX Data Objects
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.NET evolves from ADO, and is designed to deal with the issues of state, scalability and XML compatibility.
Although existing ADO developers will find all of the old ADO classes inside the ADO.NET data model, they will also find that a few new classes have been introduced, including the DataSets, DataReaders and DataSetCommands classes.
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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
C# is a new language designed to take advantage of most of the features of the .NET Framework.
C# was designed from the ground up to support component concepts like events, methods and properties.
In C#, everything is an object, which allows the creation of very clean designs.
C# was designed to make it easy to create robust and maintainable software.
C# should allow you to preserve your existing investment by integrating easily with your existing code.
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40. 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
VB.NET is a modernized version of Visual Basic. It is integrated with the .NET Framework, but still provides language constructs, features and syntax that is familiar to Visual Basic developers.
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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
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More Resources
.NET
msnews.microsoft.com news server
microsoft.public.dotnet.general newsgroup
XML
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