Chapter 12 Microsoft Assemblies

Chapter 12Microsoft Assemblies

Process Phases Discussed in This ChapterRequirementsAnalysis

Design

Implementation

ArchitectureFramework Detailed Design

xKey: = secondary emphasisx = main emphasis

Adapted from Software Design: From Programming to Architecture by Eric J. Braude (Wiley 2003), with permission.

Learning Goals for This Chapter

… Microsoft’s component (“assembly”) architecture

… where assemblies fit in .NET

… required rudiments of C#

… the contents of .NET manifests, including:

Versioning

Attributes

… the difference between private and shared assemblies

… create assemblies using C#

Understand …

Be able to …


.NET Goals and Solutions

Create interoperable components from multiple source languages

o C++, Visual Basic, ….

Solve multiple component version clashes

o “dll hell”: naming confusion in COM

Define a common runtime

Avoid registry

o Necessity to register components with host computer


Design Goal At Work: Reusability

Microsoft wanted to allow developers to create interoperable components using their favorite source languages.


The Parts of.NET

Web tools and LanguagesASP.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


Boolean

DateTime

Decimal – 28 significant digits

Double – 64-bit double-precision floating point

GUID – unique 128-bit integer; unique identifier

Int16, Int32, Int64

Sbyte – 8-bit signed integer –128 to +127

Single – 4-byte single precision floating point

TimeSpan – a period of time

Types in the CTS


Boolean Equals( Object )

Int32 GetHashCode() o Generates an integer corresponding to

the value of the object

o Used by sorting algorithms in System.Collections

Type GetType()o for the Reflection API

String ToString()

Methods of System.Object


Selected System.XX .NET Framework NameSpaces

Collections

ComponentModel

o “to implement the

runtime and design

time behavior of

components”

Data

o To deal with

databases via ADO

Drawing

IO

Net

o to interface with

common

network

protocols

Reflection

Runtime

Security

Text

o ASII, Unicode

etc.

Threading

Web

WinForms

XML Adapted from Software Design: From Programming to Architecture by Eric J. Braude (Wiley 2003), with permission.

Compilation Process in .NET

Source CodeC++VB

Compiler &metadatagenerator

IL andmetadata

Ancillary info

.dll or .exe

Base classlibrary

Classloader

IL compiler

native code

executeProcess File Key:

C#J#, Java (3rd parties)


A File

A File

A File

A File

The Parts of a .NET Assembly (Component)

Manifest Identity

o nameo version

Names of files Encrypted hash of files

to ensure integrity Specification of types

defined Names of referenced

assemblies Specification of required

security permissions

MicrosoftIntermediate

Language(IL)

Source Files A .NET assembly: xyz.dll


Key Concept: A .NET Assembly

-- includes class code from multiple files, in IL form, described by a manifest.


C# Goals 1 of 2

Rapid application developmento as with JavaBeans

Cross-platform deploymento generates character stream interpreted by .Net runtime. o as with Java Virtual Machine

Access to platform-native resourceso 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

UnlikeJava


Features of C and C++ “with the functional ease of rapid application development tools.”

Components with properties, methods and events

o built in

C# Goals : 2 of 2

UnlikeJava


HelloWorld Output


Selected C# Features

Automatic garbage collection

Allows developers to disable garbage collection

locally –

o by marking code as “unsafe”

o (e.g., where real time performance required?)

Eliminates pointers in favor of references

Introduces Interfaces

UnlikeJava


C# Web Features: Web Services

Attribute library allows wrapping of C# classes

and functions as Web services.

o a hosted software module callable over the Internet

typically via SOAP protocol.

o SOAP wraps method calls, parameters, and return

values, in XML packets.

Using appropriate attributes, programmer can

turn any C# class or function into a Web service.


Creating a .NET Component 1 of 2

csc /t:library /out:hello.dll helloFile.cs

“target”Create a library component: Don’t seek Main()

“output”Component (output) name

Input fileC# compilation


Creating a .NET Component (“Assembly”) 2 of 2

helloFile.cs

hello.dll

hello.dll

csc /t:library /out:hello.dll helloFile.cs


Using a .NET Component

csc /r:hello.dll /out:helloApp.exe helloClient.cs

hello.dllhelloClient.cs

helloApp.exe

… now execute helloApp.


Creating a .NET Component Containing Multiple Classes

csc /t:library /out:helloAuRevoir.dll

HelloAuRevoirComponentSource.cs

HelloAuRevoirComponentSource.cs

helloAuRevoir.dll

GreetingUtility HelloClass AuRevoirClass


Output For “Multiple Class” Example


Using metadata allows the CLR to support: Multiple execution models

o interpreted, o JITted (Just-in-time)o nativeo legacy code (prior to .NET)

Uniform services available to debuggers, profilers etc. Consistent exception handling Code access security Memory management Reflection Interoperability with existing unmanaged COM applications Interoperability with existing unmanaged code Optimization to match the particular CPU or environment.

Uses for Metadata

Amended from http://msdn.microsoft.com/library/default.asp


http://msdn.microsoft.com/library/default.asp





Manifest of Component helloAuRevoir.dll


Manifest Contents for helloAuRevoir.dll Component

1. -2. -3. -4. -5. -6. -7. -8. -9. -10. -11. -12. -13. -14. -15. -16. --


Manifest Detail of sayHelloWorld() in HelloClass

1. -2. -3. -4. -5. -6. -7. -8. -

Recall the source:public void SayHelloWorld( )

{ GreetingUtility.OutputMessage ( "Component says: Hello World" );

}


The Version Field of an Assembly

Major version Minor version Revision Build number


Versioning

(The process of evolving a component over time in a compatible manner.)

A new version is …

… 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)


Attributes in .NET Metadata: about …o … variableso … classeso … functions

Types of attributes:o Built-ino User-defined

Available at runtime


Output of main() in ConditionalDemo

with #define DEBUG without #define DEBUG


Output For Authorship Querying


Key Concept: A .NET Manifest Lists …

.. 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.


Design Goal At Work: Reusability

We want to reuse an assembly, confident it is the one it’s supposed to be.


Using NameSpaces

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.

Implement applications 1and 2. Exploit common components.


Namespaces Across Multiple Components

Logo

AvailabilityAnnouncement

Itinerary namespace

(Physical) File organization (3 files)

Airlines namespace

Namespace stated: Airlines.Availability Classes: Logo, AvailabilityAnnouncement

Availability namespace

ItineraryAnnouncement

Logo

(Logical) Namespace organization

Source file name: AvailabilityComponentSource.cs

Component name: availability.dll

Namespace stated: Airlines.Itinerary Class: Logo

Source file name: ItineraryLogoComponentSource.cs

Component name: itineraryLogo.dll

Namespace stated: Airlines.Itinerary Class: ItineraryAnnouncement

Source file name: ItineraryAnnouncement.cs

Component name: itineraryAnnouncmnt.dllAdapted from Software Design: From Programming to Architecture by Eric J. Braude (Wiley 2003), with permission.

Airline Reservation System Display


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


Public Key Encryption Used in .NET

Public key: …iemhdZX… Private key: …92JiuHKM3… (secret)

myKeys.snk

Hashed version Encoded version

use private

key

ManifestNames & contentsof assembly

Verification process

AssemblyInfo.cs

Assembly source

assembly

hash

OK / not OKAdapted from Software Design: From Programming to Architecture by Eric J. Braude (Wiley 2003), with permission.

Key Concept: Component Identity

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.


Summary Microsoft “assembly” == component

Microsoft distributes computing among desktops and

servers via, in part, .NET assemblies

.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”

C# language designed for .NET

Assemblies constructed via C#, VB, ... are interoperableAdapted from Software Design: From Programming to Architecture by Eric J. Braude (Wiley 2003), with permission.

Chapter 12 Microsoft Assemblies

Documents

software design

braude wiley

design goal

net goals

common runtime

interoperable components

contents of net manifests

methods of system