1. 4. Component-based Architecture

2. Component Technology. Introduction

3. Modularity Maximizing reuse complicates use - Design Patterns
- Modularity Patterns 3

4. Objective
Large distributed systems development cost reduction implies:
Programming by assembly (manufacturing) rather than development (engineering)
Reduced skills requirements
Focus expertise on domain problems
Improving software quality

5. Component Based Development for Complex Systems

6. Architectural Consequences of These Requirements:
Software should not be designed as monolithic unit but partitioned into composable services that can be spontaneously connected and orchestrated by business/technical processes (component-based software).
„Software entropy“ should be maximized:
loosely coupling between peers,
decentralized information access,
Just-in-Time Integration

7. Application Partioning
Solutions consist of collections of components.
Components are divided into multiple packages.
Packages can work with each other across a network through Object Request Broker (ORB).
This application partitioning is transparent to the component developer.

8. No Assumption on Deployment

9. A Component: Represents a logical entity.
Encapsulates some coherent functionality.
May be tested independently.
May be part of a larger piece of software.
Has well-defined provided and required interfaces for access to its functionality and for interoperability with other components.
Provides a well-defined and documented configuration interface for the adaptation to a given environment.
Is compliant with a contract specifying interfaces and quality attributes for the component.

10. Definitions of “Component”

11. Definitions of “Component”

12. Are Objects Components??

13. Blackbox Composition

14. Procedure Systems

15. Modules

16. A Linker is a Composition Operator that Composes Modules

17. What Components Provide The Parts of a Component
Set of classes
providing interfaces
Manifest
Properties
Methods
in the form of methods, published in interfaces
Reactions to Events
Ability to provide information about themselves

18. Manifests Identification of the component Authorship of the component
List of files or classes making up this component
Other components on which this one relies  
Encryption information
Means of verifying that all parts of the component are present 
Version number

19. Component Technologies
Microsoft COM+/MTS
Windows-specific Component Technology.
OpenDoc Parts
Gone with the Wind!
JavaBeans/Enterprise JavaBeans
Java-based Component Technology.
JavaSoft’s answer to MTS/COM+.

20. .NET - The Microsoft Way

21. Sun ONE (Open Net Environment)

22. You Need “Glue” How to connect (remote) components and applications:
Binary objects (components) as distribution units.
Distributed Component Models - not limited to the boundaries of a process or network node.
Homogeneous APIs on top of heterogeneous systems for encapsulating system details.
Remote Method Invocation paradigm.
Straight-forward integration of legacy code using bidirectional adapters.

23. MS Component Technologies

24. COM Principles Rigorous Encapsulation Polymorphism
Black box -- no leakage of implementation details
All object manipulation through strict interfaces
Polymorphism
via multiple interfaces per class
“Discoverable”: QueryInterface

25. COM Runtime Architecture
Pluggable Transports
Client Machine
Server Machine
Component
COM Client
TCP
Proxy
COM Runtime
COM Runtime
HTTP
Other Component

26. What is ActiveX?
A marketing name for a set of technologies and services, all based on COM (the model, the “ORB”, and the services)

27. Active Components ActiveX Controls
Are COM components with “design-time” UI
Can be written in C++, VB, Delphi, ...
Self-registering
Optimized for download and execute
Work on both Active Client or Server
Can talk indirectly over HTTP or directly over COM

28. COM (Common Object Model)
liidesed (= lepingud)
kapseldus (meetodid, omadused, sündmused)
QueryInterface – multiversionaalsus
Binaarstandard (C++, VB, ...)
DCOM (distributed) – asukoha läbipaistvus

29. MS Component Technologies:
DLL (Dynamic Link Library)
OLE (Object Linking and Embedding)
COM (Common Object Model)
ActiveX
MTS (Microsoft Transaction Server)
MSMQ (Microsoft Message Queue)
COM+
Windows DNA (Distributed interNet Application)
CLR (Common Language Runtime)

30. MS Component Technologies
.net

31. Evolution of Component Architectures

32. .NET

33. .NET-protsessid

34. Visual Studio.NET Language Architecture
C++ to IL
Translator IL
Assemblies
C++ Code
VB to IL
Translator IL
VB Code
IL = Intermediate Language

35. Visual Studio.NET Language Architecture
Common Language Runtime (CLR)
Assemblies
JIT Compiler
System Services

36. Visual Studio.NET The IL Early Compiler
Common Language Runtime (CLR)
Assemblies
Early Compiler
System Services

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

38. The Parts of a .NET Assembly (Component)
Source Files
A .NET assembly: xyz.dll
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
A File
Microsoft
Intermediate
Language
(IL)
A File
A File
A File

39. Common Language Runtime (CLR)
.NET-käituskeskkond
haldab programmi käituse (execution management)
tagab teenused (provides services)
Hallatud kood (managed code), tagab keeltevahelise:
integratsiooni (cross language integration)
versioonihalduse
automaatse mäluhalduse
isekirjelduvad objektid (IDL-i pole vaja)
”Compile once, run verywhere”
...

40. CLR - metaandmed Kompilaatorid loovad koos koodiga ka metaandmed, mis:
kirjeldavad komponente, objekte ja käitustingimusi (klasside asukoht ja laadimine, koodi genereerimine, käituskontekst, ...)
tagavad automaatse objektide eluea (garbage collection)
CLRi toetavad: Visual Basic, C#, Visual C++, Perl (¬MS), COBOL (¬MS)  Common Language Specification (CLS)

41. CLR - MSIL

42. CLR - JIT
Osa programmi ei täideta konkreetses käituses  MSIL-kood konverteeritakse masinakoodiks ja laaditakse mällu vaid siis, kui vaja
Laadur loob igale meetodile vahendaja (stub)
Järgnevad pöördumised suunatakse juba loodud masinakoodi poole
Konverteerimisel verifitseeritakse koodi metaandmeid kasutatades – safe code

43. COM vs CLR
COM võimaldab erinevates keeltes kirjutatud komponentide interaktsiooni, koostööd
CLR integreerib keeled ja võimaldab ühe keele objektidel kasutada teises keeles kirjutatud objekte – Common Language Specification (CLS)

44. Java Architecture

45. Java Architecture Network .java .class load load load Browser
file
Compiler
.java
byte
codes
.class
load
JVM
load
java byte code
os/hardware
JVM
std libs
load
Browser
java byte code
os/hardware
JVM
std libs
APPLICATION
APPLET

46. Java to byte code Java byte code Java to byte code Translator
Java Code

47. Java Virtual Machine Java Virtual Machine (JVM) Java byte code
JIT Compiler
System Services

48. Java – the Byte Code Early Compiler
Java Virtual Machine (JVM)
Byte Code
Early Compiler
System Services

49. Component and deployment diagrams

50. Component Diagram

51. Component Diagrams

52. Component Notation A component is shown as a rectangle with
A keyword <<component>>
Optionally, in the right hand corner a component icon can be displayed
A component icon is a rectangle with two smaller rectangles jutting out from the left-hand side
This symbol is a visual stereotype
The component name
Components can be labelled with a stereotype
there are a number of standard stereotypes ex: <<entity>>, <<subsystem>>

53. Component Diagram

54. Component Elements A component can have Interfaces Usage dependencies
An interface represents a declaration of a set of
operations and obligations
Usage dependencies
A usage dependency is relationship which one element
requires another element for its full implementation
Ports
Port represents an interaction point between a component
and its environment
Connectors
Connect two components
Connect the external contract of a component to the internal structure

55. Interface
A component defines its behaviour in terms of provided and required interfaces
An interface
Is the definition of a collection of one or more operations
Provides only the operations but not the implementation
Implementation is normally provided by a class/ component
In complex systems, the physical implementation is provided by a group of classes rather than a single class

56. Interface
May be shown using a rectangle symbol with a keyword <<interface>> preceding the name
For displaying the full signature, the interface rectangle can be expanded to show details
Can be
Provided
Required

57. Interface A provided interface
Characterize services that the component offers to its environment
Is modeled using a ball, labelled with the name, attached by a solid line to the component
A required interface
Characterize services that the component expects from its environment
Is modeled using a socket, labelled with the name, attached by a solid line to the component

58. Interface
Where two components/classes provide and require the same interface, these two notations may be combined
The ball-and-socket notation hint at that interface in question serves to mediate interactions between the two components
If an interface is shown using the rectangle symbol, we can use an alternative notation, using dependency arrows

59. Port Specifies a distinct interaction point
Between that component and its environment
Between that component and its internal parts
Is shown as a small square symbol
Ports can be named, and the name is placed near the square symbol
Is associated with the interfaces that specify the nature of the interactions that may occur over a port

60. External View A component have an external view and an internal view
An external view (or black box view) shows publicly visible properties and operations
An external view of a component is by means of interface symbols sticking out of the component box
The interface can be listed in the compartment of a component box

61. Internal View
An internal, or white box view of a component is where the realizing classes/components are nested within the component shape
Realization is a relationship between two set of model elements
One represents a specification
The other represent an implementation of the latter

62. Internal View
The internal class that realize the behavior of a component may be displayed in an additional compartment
Compartments can also be used to display parts, connectors or implementation artifacts
An artifact is the specification of a phisycal piece of information

63. Internal View
Components can be built recursively

64. Deployment Diagrams
There is a strong link between components diagrams and deployment diagrams
Deployment diagrams
Show the physical relationship between hardware and software in a system
Hardware elements:
Computers (clients, servers)
Embedded processors
Devices (sensors, peripherals)
Are used to show the nodes where software components reside in the run-time system

65. Deployment Diagram
Describes the configuration of hardware in a system in terms of nodes and connections
Describes the physical relationships between software and hardware
Displays how artifacts are installed and move around a distributed system

66. Deployment Diagrams Deployment diagram Contains nodes and connections
A node usually represent a piece of hardware in the system
A connection depicts the communication path used by the hardware to communicate
Usually indicates the method such as TCP/IP

67. Deployment Diagrams Deployment diagrams contain artifact An artifact
Is the specification of a phisycal piece of information
Ex: source files, binary executable files, table in a database system,….
An artifact defined by the user represents a concrete element in the physical world

68. Deployment Diagrams An artifact manifest one or more model elements
A <<manifestation>> is the concrete physical of one or more model elements by an artifact
This model element often is a component
A manifestation is notated as a dashed line with an open arrow-head labeled with the keyword <<manifest>>

69. Deployment Diagrams

70. A Statement of Charles Darwin