1. .NET Architecture

1. .NET Architecture

Based on slides by Joe Hummel

2UCN Technology: Computer Science - 2012

Aim

“Microsoft .NET is based on the Common Language Runtime (CLR) and an extensive set of Framework Class Libraries (FCL). The CLR defines a common programming model and a standard type system for cross-platform, multi-language development.”

• CLR-based execution• Application design• Component-based development


Part 1

• CLR-based execution…


Inspiration

• .NET is inspired by a number of elements

.NET

OOP JVM

GUIWeb

component-based design n-tier design


.NET supports a number of languages

• .NET supports VB, C# (C-sharp), C++, J# (Java 1.1), Eiffel, etc.

code.vb code.cs code.cpp ...

Development Tools

app.exe

FCL


.NET is “platform independent”

• Compiled .NET applications run on all supported platforms:

APP.exe

?Win64 Win32

(XP,2K,98)Windows Phone

CIL: Common Intermediate

Language


CLR-based execution

• .NET applications are not stand-alone .exe-programs

APP.exe

other FCL components

CLR

JIT Compiler

obj code

OS Process

Underlying OS and HW

Core FCLCompare

to Java JVM

View the CIL Code

(“byte code”): ILDASM


Java Virtual Machine

Execution of Java programs

source(xxx.java)

compiler

CPU

bytecode(xxx.class)

Interpreterfortolker


CLR-based execution implies:• Clients need CLR & core FCL to run .NET apps

– Obtained through Redistributable .NET Framework– Runs on Windows 98 and higher, NT (sp6a) and higher– Runtime is integrated in Windows Vista, Windows 7,

Windows 8 and Windows Phone 7+.• Design issues…

+ managed execution (memory protection, etc.)+ portability:

• general assembly language• FCL = layer of abstraction between app and OS

– slower execution?• JIT compilation is expensive• But the JIT-compiler may take advantage of specific

target HW• pre-JIT is possible


Part 2

• Application Design…


• Often applications are designed as N "tiers"– good separation of responsibility– allows the same back-end tier for different clients

object

Application Design

Front-end

object

object

Business

Presentation Data Access Data


Physical Design

• Where should tiers be physically deployed?– There are a range of different designs…

• Most common are:– locally– remote– web app– web service


(1) Local Design• Local implies that tiers are all deployed on one local

computer– though may data be on a remote computer

FEobj obj

obj

• Pros? – Simple to develop!

• Cons? – Hard to deploy and maintain– Are to be installed and configured on every client


(2) Remote Design• If Remote Design is used then the presentation (user

interface, front end) runs on a separate computer

FEobj obj

obj

• Pros? – Easier to maintain, back-end tiers May be updated without any

changes on the clients.– More secure, since the database only is accessed from the

server, and directly from the client.• Cons?

– Clients Must often use the same OS as the server; firewalls may cause troubles.

proprietary protocols

ServerClient


(3) Web App Design

• In Web app presentation is generated by a Web server

obj obj

obj

Browser

ANY platform

Web server

• Pros?– scales to the internet, enhances the user group of the

applications.– No firewall problems (HTTP / port 80 communication only)

• Cons? – browser-based clients have limited functionality.

HTML / HTTP

WebPage

Server


(4) Web Service Design

• Web services are objects that are available through Web technology

• In stead of HTML data is communicated in XML

obj obj

obj

custom FE

ANY platform

Server

Web server

XML / SOAP

obj

• Pros? – Open! Opens for integration of applications.

• Cons? – A technology under development…

other APP

ANY platform


WCF – Window Communication Foundation

obj obj

obj

custom FE

ANY platform

Server

Web server

XML / SOAP / REST…And proprietary binary protocols

obj

other APP

ANY platform

• The new way of doing it: Supports • web-services (HTTP-based),• binary protocols (remoting) and• and much more (p2p, message queuing …)


Part 3

• Component-based Development…


Component-based Development

• Application tier is usually build from many components/classes/objects.

• E.g..:– A typical GUI application with local design has 3 components

packed as 1 EXE and 2 DLL

Front-end

object object

object

app.exebusiness.dll data.dll


Assemblies• .NET packs components in what is known as assemblies• 1 assembly = 1 or more compiled classes

– .EXE represents an assembly with classes + Main program– .DLL represents an assembly with classes

Development Tools

.EXE / .DLL

code.vbcode.vb

code.cs

assembly


CLR-based execution revisited

• All assemblies must be present:

.EXE

other FCL assemblies

CLR

JIT Compiler

obj code

OS Process

Underlying OS and HW

Core FCLassembly

.DLL.DLL.DLL

obj codeobj code

obj code


Assembly – where are they?

• How does CLR find the needed assemblies?

• So far this is sufficient:– DLL-files must be in the same directory as the EXE– FCL assemblies are in GAC (Global Assembly Cache)– CLR starts looking in GAC, the in the directory of the EXE…


GAC?

• GAC = Global Assembly Cache– C:\Windows or C:\WinNT katalog

• Observations:– Windows Explorer gives a flat view of GAC.– Command prompt gives the real view.– GAC may have different versions of same assembly.– Some assemblies are pre-JIT-compiled ("native image").– Hacker-proof by digital signature…


Summing up

• .NET architecture is:– multi-language– cross-platform– based on CLR, FCL, and JIT

• Application design is typically multi-tier• Application design provides component-based development

– .NET components are packed as assemblies


References

• Textbooks:– J. Richter, "Applied Microsoft .NET Framework Programming"– T. Thai and H. Lam, ".NET Framework Essentials"

• Web sites:– http://msdn.microsoft.com/net– http://www.gotdotnet.com/

http://msdn.microsoft.com/net

http://www.gotdotnet.com/

2. .NET Development

Aim:

“Microsoft .NET development is based on an underlying framework of tools and classes. These tools and classes are known as the Framework SDK (Software Development Kit).”


.NET Development

• 3 sets of tools for developing assemblies:

1) .NET Framework SDK• Free (100 MB)• complete set of command-line tools and documentation• Available for Windows NT, 2000, XP Pro, Vista and 7

• Other platforms?– Mac OS X via Rotor (i.e. SSCLI)– Linux (and Mac??) via Mono project


.NET Development

2) Visual Studio .NET• Huge – available from eAcademy• Powerful integrated development environment (IDE)• One IDE for everything: GUI builder, database

connections, web-based, web service, DLLs, etc.• Used by 99% of the developers• $$

3) Free IDEs• Express Editions of Visual Studio• #develop, simplified clone of VS.NET• WebMatrix, for web-based applications


Summing Up

• .NET is multi-language– SDK Framework based on C# and VB.NET– But many other languages are supported as well

• .NET-development is component-based– Auxiliary classes are implemented as one or more DLLs– .EXE is implemented using the DLLs.– if (assembly A is using a class from assembly B)

A must reference B!;


References

• Textbooks:– Andrew Troelsen.: Pro C# 2010 and the .NET 4 Platform, 5th Ed.

(new edition is announced).– J. Richter, "Applied Microsoft .NET Framework Programming"

• Web sites:– http://msdn.microsoft.com/net– MSDNAA: http://www.msdnaa.net/– Mono: http://www.mono-project.com– Free IDEs:

• http://www.icsharpcode.net/OpenSource/SD/default.asp• http://www.asp.net/webmatrix/

http://msdn.microsoft.com/net

http://www.msdnaa.net/

http://www.mono-project.com/

http://www.mono-project.com/

http://www.go-mono.com/

http://www.go-mono.com/

http://www.icsharpcode.net/OpenSource/SD/default.asp


References

• More textbooks:– T. Archer and A. Whitechapel, "Inside C#" (2nd edition)– S. Lippman, "C# Primer"– J. Mayo, "C# Unleashed“– Anders Hejsberg, Mads Torgersen, Scott Wiltamuth, Peter

Golde: “The C# Programming Language”. Third Edition

1. .NET Architecture

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