Chapter 12 Microsoft Assemblies. Software Architecture Microsoft Assemblies 1

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1 Chapter 12 Microsoft Assemblies 1

2 Process Phases Discussed in This Chapter Requirements Analysis Design Framework Architecture Detailed Design Key: x = main emphasis x = secondary emphasis Implementation 2

3 Learning Goals for This Chapter Understand q Microsoft s component ( assembly ) architecture q where assemblies fit in.net q required rudiments of C# q the contents of.net manifests, including: Versioning Attributes q the difference between private and shared assemblies Be able to q create assemblies using C# 3

4 .NET Goals and Solutions q Create interoperable components from multiple source languages o C++, Visual Basic,. q Solve multiple component version clashes o dll hell : naming confusion in COM q Define a common runtime q Avoid registry o Necessity to register components with host computer 4

5 Design Goal At Work: à Reusability ß Microsoft wanted to allow developers to create interoperable components using their favorite source languages. 5

6 The Parts of.net Web tools and Languages ASP.NET, Windows Forms; Visual Basic.NET, C#.NET Framework Classes net XML IO Security.... Common Language Runtime (CLR) Memory Management Common Type System (CTS).... uses uses 6

7 q Boolean q DateTime Types in the CTS q Decimal 28 significant digits q Double 64-bit double-precision floating point q GUID unique 128-bit integer; unique identifier q Int16, Int32, Int64 q Sbyte 8-bit signed integer 128 to +127 q Single 4-byte single precision floating point q TimeSpan a period of time 7

8 Methods of System.Object q Boolean Equals( Object ) q Int32 GetHashCode() o Generates an integer corresponding to the value of the object o Used by sorting algorithms in System.Collections q Type GetType() o for the Reflection API q String ToString() 8

9 Selected System.XX.NET Framework NameSpaces q Collections q ComponentModel o to implement the runtime and design time behavior of components q Data o To deal with databases via ADO q Drawing q IO q Net o to interface with common network protocols q Reflection q Runtime Security Text ASII, Unicode etc. Threading Web WinForms XML 9

10 Compilation Process in.net Base class library Ancillary info Source Code C++ VB C# J#, Java (3 rd parties) Compiler & metadata generator IL and metadata.dll or.exe Class loader IL compiler native code Key: Process File execute 10

11 The Parts of a.net Assembly (Component) Source Files A.NET assembly: xyz.dll A File A File A File A File Manifest Identity name version Names of files Encrypted hash of files to ensure integrity Specification of types defined Names of referenced assemblies Specification of required security permissions Microsoft Intermediate Language (IL) 11

12 Key Concept: à A.NET Assembly ß -- includes class code from multiple files, in IL form, described by a manifest. 12

13 C# Goals 1 of 2 Rapid application development as with JavaBeans Cross-platform deployment generates character stream interpreted by.net runtime. as with Java Virtual Machine Access to platform-native resources take advantage of the Windows API to run as a full-featured application on Windows 2000 Support for the COM and.net platforms Unlike Java Unlike Java 13

14 C# Goals : 2 of 2 q Features of C and C++ with the functional ease of rapid application development tools. q Components with properties, methods and events o built in Unlike Java 14

15 HelloWorld Output 15

16 Selected C# Features Automatic garbage collection Allows developers to disable garbage collection locally by marking code as unsafe (e.g., where real time performance required?) Unlike Java Eliminates pointers in favor of references Introduces Interfaces 16

17 C# Web Features: Web Services q Attribute library allows wrapping of C# classes and functions as Web services. a hosted software module callable over the Internet typically via SOAP protocol. SOAP wraps method calls, parameters, and return values, in XML packets. q Using appropriate attributes, programmer can turn any C# class or function into a Web service. 17

18 Creating a.net Component 1 of 2 C# compilation Input file csc /t:library /out:hello.dll hellofile.cs output Component (output) name target Create a library component: Don t seek Main() 18

19 Creating a.net Component ( Assembly ) 2 of 2 hellofile.cs csc /t:library /out:hello.dll hellofile.cs hello.dll hello.dll 19

20 Using a.net Component helloclient.cs hello.dll csc /r:hello.dll /out:helloapp.exe helloclient.cs helloapp.exe now execute helloapp. 20

21 Creating a.net Component Containing Multiple Classes GreetingUtility HelloClass AuRevoirClass HelloAuRevoirComponentSource.cs csc /t:library /out:helloaurevoir.dll HelloAuRevoirComponentSource.cs helloaurevoir.dll 21

22 Output For Multiple Class Example 22

23 Using metadata allows the CLR to support: q Multiple execution models o interpreted, o JITted (Just-in-time) o native o legacy code (prior to.net) q Uniform services available to debuggers, profilers etc. q Consistent exception handling q Code access security q Memory management q Reflection Uses for Metadata Amended from library/default.asp q Interoperability with existing unmanaged COM applications q Interoperability with existing unmanaged code q Optimization to match the particular CPU or environment. 23

24 Manifest of Component helloaurevo ir.dll 24

25 Manifest Contents for helloaurevoir.dll Component

26 Manifest Detail of sayhelloworld() in HelloClass Recall the source: public void SayHelloWorld( ) { GreetingUtility.OutputMessage ( "Component says: Hello World" ); } 26

27 The Version Field of an Assembly Major version Minor version Revision Build number 27

28 Versioning (The process of evolving a component over time in a compatible manner.) A new version is q q source compatible with a previous version if code that depends on the previous version can, when recompiled, work with the new version. binary compatible if code that depended on the old version can, without recompilation, work with the new version. (adapted from Microsoft) 28

29 Attributes in.net q q q Metadata: about o variables o o classes functions Types of attributes: Built-in User-defined Available at runtime 29

30 Output of main() in ConditionalDemo with #define DEBUG without #define DEBUG 30

31 Output For Authorship Querying 31

32 Key Concept: à A.NET Manifest Lists ß.. the files containing the IL-compiled classes, the.net components on which the assembly depends, version numbers, attributes, and encrypted hash to verify not tampered in transit. 32

33 Design Goal At Work: à Reusability ß We want to reuse an assembly, confident it is the one it s supposed to be. 33

34 Using NameSpaces Implement applications 1and 2. Exploit common components. Application 1: List available flights in following form <Animated airline logo goes here> <Material introducing available flights here > From <city> to <city> departing at <time> and arriving at <time>. <Animated logo of the Intergalactic Reservation Service goes here> Application 2: List bookings already made in following form <Animated logo of the Intergalactic Reservation Service goes here > <Material introducing instructions to the traveler goes here > Please arrive at <time> at <city> airport for your flight. 34

35 (Logical) Namespace organization Airlines namespace Availability namespace Logo AvailabilityAnnouncement Itinerary namespace Logo (Physical) File organization (3 files) Source file name: AvailabilityComponentSource.cs Namespace stated: Airlines.Availability Classes: Logo, AvailabilityAnnouncement Component name: availability.dll Source file name: ItineraryLogoComponentSource.cs Namespace stated: Airlines.Itinerary Class: Logo Component name: itinerarylogo.dll ItineraryAnnouncement Namespaces Across Multiple Components Source file name: ItineraryAnnouncement.cs Namespace stated: Airlines.Itinerary Class: ItineraryAnnouncement Component name: itineraryannouncmnt.dll 35

36 Airline Reservation System Display 36

37 Public Key Cryptography Any message encoded with one key can be decoded with the other. One can t encrypt and decrypt a message with the same key. It s practically impossible to deduce one key from the other. It s very unlikely that an encoded document can be decoded with an unmatched key 37

38 Public key: iemhdzx Private key: 92JiuHKM3 (secret) mykeys.snk Hashed version use private key Encoded version AssemblyInfo.cs hash Assembly source Public Key Encryption Used in.net Names & contents of assembly assembly Verification process Manifest OK / not OK 38

39 Key Concept: à Component Identity ß To ensure that the component we are using is the one intended, we use relatively or globally unique names:.net also applies tamper-proofing via public key encryption. 39

40 q Microsoft assembly == component Summary q Microsoft distributes computing among desktops and servers via, in part,.net assemblies q.net assemblies supercede and are more versatile than (D)COM(+) objects. o Exist in Intermediate Language o Permit versioning o Include attribute feature o Identity technique for shared assemblies reduces dll hell q C# language designed for.net q Assemblies constructed via C#, VB,... are interoperable 40

Department of Computer Applications

Department of Computer Applications MCA 512:.NET framework and C# [Part I : Medium Answer type Questions] Unit - 1 Q1. What different tools are available and used to develop.net Applications? Hint a).net Framework SDK b) ASP.NET Web Matrix