1..NET Architecture Based on slides by Joe Hummel

2 UCN Technology: Computer Science 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

3 UCN Technology: Computer Science Part 1 CLR-based execution…

4 UCN Technology: Computer Science Inspiration.NET is inspired by a number of elements.NET OOP JVM GUI Web component-based design n-tier design

5 UCN Technology: Computer Science NET supports a number of languages.NET supports VB, C# (C-sharp), C++, J# (Java 1.1), Eiffel, etc. code.vbcode.cscode.cpp... Development Tools app.exe FCL

6 UCN Technology: Computer Science NET is “platform independent” Compiled.NET applications run on all supported platforms: APP.exe ? Win64Win32 ( XP,2K,98) Windows Phone CIL: Common Intermediate Language

7 UCN Technology: Computer Science 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 FCL Compare to Java JVM View the CIL Code (“byte code”): ILDASM

8 UCN Technology: Computer Science Java Virtual Machine Execution of Java programs source (xxx.java) compiler CPU bytecode (xxx.class) Interpreter fortolker

9 UCN Technology: Computer Science 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

10 UCN Technology: Computer Science Part 2 Application Design…

11 UCN Technology: Computer Science 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 BusinessPresentationData AccessData

12 UCN Technology: Computer Science Physical Design Where should tiers be physically deployed? –There are a range of different designs… Most common are: –locally –remote –web app –web service

13 UCN Technology: Computer Science (1) Local Design Local implies that tiers are all deployed on one local computer –though may data be on a remote computer FE obj Pros? –Simple to develop! Cons? –Hard to deploy and maintain –Are to be installed and configured on every client

14 UCN Technology: Computer Science (2) Remote Design If Remote Design is used then the presentation (user interface, front end) runs on a separate computer FE 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 Server Client

15 UCN Technology: Computer Science (3) Web App Design In Web app presentation is generated by a Web server 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 Web Page Server

16 UCN Technology: Computer Science (4) Web Service Design Web services are objects that are available through Web technology In stead of HTML data is communicated in XML 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

17 UCN Technology: Computer Science WCF – Window Communication Foundation 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 …)

18 UCN Technology: Computer Science Part 3 Component-based Development…

19 UCN Technology: Computer Science 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 app.exe business.dll data.dll

20 UCN Technology: Computer Science 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.vb code.cs assembly

21 UCN Technology: Computer Science 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 FCL assembly.DLL obj code

22 UCN Technology: Computer Science 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…

23 UCN Technology: Computer Science 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…

24 UCN Technology: Computer Science 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

25 UCN Technology: Computer Science References Textbooks: –J. Richter, "Applied Microsoft.NET Framework Programming" –T. Thai and H. Lam, ".NET Framework Essentials" Web sites: – –

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).”

27 UCN Technology: Computer Science 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

28 UCN Technology: Computer Science 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

29 UCN Technology: Computer Science 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!;

30 UCN Technology: Computer Science References Textbooks: –Andrew Troelsen.: Pro C# 2010 and the.NET 4 Platform, 5 th Ed. (new edition is announced). –J. Richter, "Applied Microsoft.NET Framework Programming" Web sites: – –MSDNAA: –Mono: –Free IDEs:

31 UCN Technology: Computer Science References More textbooks: –T. Archer and A. Whitechapel, "Inside C#" (2 nd edition) –S. Lippman, "C# Primer" –J. Mayo, "C# Unleashed“ –Anders Hejsberg, Mads Torgersen, Scott Wiltamuth, Peter Golde: “The C# Programming Language”. Third Edition