Structural Modelling

Transcription

1 Structural Modelling Budapesti Műszaki és Gazdaságtudományi Egyetem Hibatűrő Rendszerek Kutatócsoport Budapesti Műszaki és Gazdaságtudományi Egyetem Méréstechnika és Információs Rendszerek Tanszék 1

2 Topics of the Lecture Goals and Applications of Structural Modelling Decomposition Description of the Model Elements by Graphs Property Modelling 2

3 Goals, Applications Decomposition Graphs Properties STATIC MODELLING Examples: Architecture Building Corporate network How can the structure of complex systems be clearly modelled? 3

4 Definition: Structural Model Structural models are static. Their basis are (sub-)systems that are divided into their ingredients by the relation Part of. Die ingredients can be the followings: further divided subsystems or further not divided (elementary) components. The structural model represents the structure of the system according its ingredients, the properties of the ingredients and their relationships among each other. 4

5 Example: Architecture Models BIM (Building Information Model) Modelling the whole building in a single model Views o Gas pipe system o Isolation o Water pipe and sewerage system o Electric installation plan o etc. 5

6 Office in a Production Hall 6

7 Gas Pipe System 7

8 Isolation 8

9 Water and Sewerage System 9

10 Electric Installation Plan 10

11 Goal of Structural Modelling Dividing a system o It is simpler to design smaller units o Usage of already existing parts o Usage of commercial components Documentation of an existing system o System overview Defining data structures (COTS - Commercial off-the-shelf) o What pieces of information should be there? o Relationships of the pieces 11

12 Example: Robot Vacuum Cleaner Roller gear Control unit Vacuum cleaner 12

13 Structural and Behavioural Modelling Structural o static o whole and part, components The main components of the robot vacuum cleaner are the control unit, the roller gear and the vacuum cleaner. o connections Behavioural o dynamic o timeliness o states, processes o reactions to the environment (context) This categorization is neither full nor disjoint... For the command to right changes the roller gear its operational mode to turn. The roller gear of the robot intervenes when signals of the sensors are received. (When, how?) 13

14 Structural Model The knowledge about the structure of the system o What parts consists the system of? o How are they connected? o What kind of properties do the elements have? 14

15 Example: Corporate Network Router Internet Firewall Smartphone Switch Server Workstation Wifi Laptop Smartphone Workstation Workstation Printer 15

16 Example: Corporate Network Internet Firewall Router Is there a single point of failure (SPOF) in the system? Server Workstation Is the Internet reachable? Workstation Switch Is the WLAN overloaded, how many computers Workstation are connected? Printer Wifi Smartphone Smartphone What elements consists the network of? Laptop 16

17 Goals, Applications Decomposition Graphs Properties STRUCTURAL DECOMPOSITION What containedness relationships are there among the subsystems? Examples: Robot vacuum cleaner Registration office 17

18 Definition: Decomposition Structural models are static. Their basis are (sub-)systems that are divided into their ingredients by the relation Part of. Decomposition ( faktoring ) is the division of a complex problem or system into smaller parts that are easier to conceive, understand, design, implement/program and maintain. Hierarchical Decomposition: o Multi-level whole-part relationship Meaning of the relation Part of: o Physical Decomposition: Part of = spatial division o Logical Decomposition: Part of = functional division 18

19 Types of Decomposition Physical decomposition o What pieces does it consists of? Logical decomposition by functions o What does it do? Robot vacuum cleaner Discovery and navigation subsystem Cleaning subsystem Monitoring subsytem Moving subsystem Sensor subsystem 19

20 Definition: Correctness of Decomposition A decomposition is correct, if each element of the system resulting from the decomposition corresponds to an element of the original system, and each element of the original system corresponds to some elements of the system resulting from the decomposition. 20

21 Top-down Development Elementary step: Decomposition Registration office Computer devices PC Cabling POS-Terminal Document printer Monitor Mouse Keyboard Desktop-PC Photo cabin Building environment Background Chair Desktop Counter Light Photo device Chair Locker 21

22 Bottom-up Development Elementary step: Composition Sozial network Server infrastructure Server-side software Web server DB server Database Application Static content server Advertisements Monitoring Web interface Interface-Desing (UX) Mobile interface Graphics Dynamics (JS) 22

23 Top-down Top-down and Bottom-up Roles of the subsystems are during development already known There are no functioning parts during development Subsysteme Problems/Reqs of the subsystems are revealed late Bottom-up System Subsysteme der Subsysteme Subsystems can be tested step-by-step There are always some functioning parts during development System Exact roles of the subsystems are revealed late Not only in structural modelling Mixed approaches, iterative Development Subsysteme Subsysteme der Subsysteme 23

24 Goals, Applications Decomposition Graphs Properties STRUCTURAL MODELS What kind of relationships are there among the subsystems? Examples Transport network File system 24

25 Graph Representation Human way of thinking:,,connections of Things o Things: persons, airports, areas o Connections: dependency, acquaintance, flights, containment Mathematical Formalism: Graph o Nodes o Edges o (Properties) XMind 25

26 Definitions in Computer Engineering In the computer engineering everything has several, often contradicting definitions o System =? o Model =? The same term is often named with different names o node, vertex, object, concept o edge, link, arc, connection, relationship Always pick one! 26

27 Budapest Rail-bound Transport Network M2 M3 M4 4-6 Deák Ferenc square Square of the Franciscans Astoria Kálvin square Boráros square Blaha Lujza square Rákóczi square Corvin estate 27

28 Budapest Rail-bound Transport Network Deák Ferenc square 2 2 Astoria 1 Blaha Lujza square M2 M3 M4 4-6 Square of the Franciscans 1 Kálvin square Rákóczi square 2 Corvin estate Boráros square Shortest path? 28

29 Filtering: by edge labels (Subgraphs) E.g. show the underground network only Deák Ferenc square Astoria Blaha Lujza square M2 M3 M4 Square of the Franciscans Kálvin square Rákóczi square Corvin estate Boráros square Was is reachable by the underground only? 29

30 Budapest V. district LEOPOLD TOWN DOWNTOWN 30

31 Budapest V. district Hierarchical Model V. district Kossuth Lajos square LEOPOLD TOWN Leopold town Downtown Deák Ferenc square DOWNTOWN Square of the Franciscans Deák Ferenc square Kossuth Lajos square Square of the Franciscans 31

32 Simple Graphs Deák Ferenc square Square of the Franciscans Astoria Transport network: undirected graph Kálvin square How can it be made directed? Blaha Lujza square Rákóczi square Areas: directed graph Leopold town V. district Downtown Corvin estate Boráros square Deák Ferenc square Kossuth Lajos square Square of the Franciscans 32

33 Simple Graphs Deák Ferenc square Astoria V. district Square of the Franciscans Kálvin square Blaha Lujza square Rákóczi square Leopold town Downtown Corvin estate Boráros square Deák Ferenc square Kossuth Lajos square Square of the Franciscans 33

34 Typed Graph Deák Ferenc square Astoria V. district Square of the Franciscans Kálvin square Blaha Lujza square Rákóczi square VIII. district Budapest Corvin estate IX. district Boráros square 34

35 Graphical User Interface Representation of a tree structure o as graph o as containment relation Window Menu Main View Edit Help Display Degrad MC 35 Degrees Radians Grads

36 Representation of a Tree Structure File system C: \Documents \Pictures \logo.png \groundplot.jpg \contracts.pdf \Drivers How much storage capacity can be gained by deleting the directory Documents? 36

37 Characteristics of a File System How much storage capacity can be gained by deleting the directory Documents? Some further Parameter are required Name Type Size (kb) Last modified Documents directory Contracts.pdf file Pictures directory Logo.png file Groundplot.jpg file Knowing these pieces of information and the file hierarchy the question can be answered. 37

38 Goals, Applications Decomposition Graphs Properties MODELLING THE PROPERTIES What properties do have the individual components? Examples Tables Databases 38

39 Definition: Property Properties of the elements of a model can also be described. A property is a function that is defined over the elements of a model and partial (values may be undefined), and the value set of which is the set of the possible values of the given property. 39

40 Tabular Representation Rows of the table = Model elements Columns of the table = Properties Name Type Size (kb) Last modified Documents directory Contracts.pdf file Pictures directory Logo.png file Groundplot.jpg file NULL / NA Attributes 40

41 Definition: Filtering During filtering a filtering condition is evaluated over the elements of the model, and the submodel is kept that consists exactly of the elements satisfying the condition. o Type = file" Name Type Size (kb) Last modified Contracts.pdf file Logo.png file Groundplot.jpg file o Size > 1000 kb Name Type Size (kb) Last modified Groundplot.jpg file

42 Definition: Projection During projection some parameters of the model are chosen, others are omitted. Name Type Size (kb) Last modified Documents directory Contracts.pdf file Pictures directory Logo.png file Groundplot.jpg file Projection: {Name, Size} Name Size (kb) Documents Contracts.pdf 569 Pictures Logo.png 92 Groundplot.jpg

43 SUMMARY 43

44 Definition: Structural Model Structural models are static. Their basis are (sub-)systems that are divided into their ingredients by the relation Part of. Die ingredients can be the followings: further divided subsystems or further not divided (elementary) components. The structural model represents the structure of the system according its ingredients, the properties of the ingredients and their relationships among each other. 44

45 Example: Corporate Network Router Internet Firewall Smartphone Switch Server Workstation Wifi Laptop Smartphone Workstation Workstation Printer 45

46 Definition: Decomposition Structural models are static. Their basis are (sub-)systems that are divided into their ingredients by the relation Part of. Decomposition ( faktoring ) is the division of a complex problem or system into smaller parts that are easier to conceive, understand, design, implement/program and maintain. Hierarchical Decomposition: o Multi-level whole-part relationship Meaning of the relation Part of: o Physical Decomposition: Part of = spatial division o Logical Decomposition: Part of = functional division 46

47 Top-down Top-down and Bottom-up Roles of the subsystems are during development already known There are no functioning parts during development Subsysteme Problems/Reqs of the subsystems are revealed late Bottom-up System Subsysteme der Subsysteme Subsystems can be tested step-by-step There are always some functioning parts during development System Exact roles of the subsystems are revealed late Not only in structural modelling Mixed approaches, iterative Development Subsysteme Subsysteme der Subsysteme 47

48 Typed Graph Deák Ferenc square Astoria V. district Square of the Franciscans Kálvin square Blaha Lujza square Rákóczi square VIII. district Budapest Corvin estate IX. district Boráros square 48

49 Tabular Representation Rows of the table = Model elements Columns of the table = Properties Name Type Size (kb) Last modified Documents directory Contracts.pdf file Pictures directory Logo.png file Groundplot.jpg file NULL / NA Attributes 49

50 Summary 50

51 MODELLING TYPES 51

52 Example: The Galaxis Areas Containment- Relation 52

53 Example: The Galaxis The Galaxy Core Worlds Outer Rim Coruscant Alderaan Tatooine 53

54 Categorisation of Model Elements in Types Example: Can the Colour of Lightsaber of Yoda change? o No Yoda an entity with green lightsaber Important/relevant attribute? o Yes Colour of Lightsaber no characteristic attribute Type: Entirety of elements that are distinguished by similar attributes 54

55 Type and Attributes Type is a part of the knowledge, implicitly expressed in the label o Type is a special property o Other properties: attributes Widely used Convention: o Attributes may sometimes change (but they do not have to) o Type is permanent (forever) 55

56 Type Graph A type node for each node type A type edge for each edge type Metamodell Depot Place Place Remise Stop Stop Depot Garage Remise Garage 56

57 Type Graph A type node for each node type A type edge for each edge type Metamodell Person Warrior Jedi Sith Person is a Warrior is a is a Jedi Sith Hierarchic Decomposition 57

58 Representation of Type-Instance Relations instanceof Person Darth Vader Mace Windu Yoda is a Warrior Luke Skywalker is a is a Leia Organa Jedi Sith Jabba 58

59 Representation of Type-Instance Relations instanceof Person Darth Vader Mace Windu Yoda is a Warrior Luke Skywalker is a is a Leia Organa Jedi Sith Jabba (Instance) Model Metamodel 59

60 Representation of Types as Attributes name: Darth Vader type: Sith name: Mace Windu type: Jedi name: Yoda type: Jedi name: Leia Organa type: person (Instance) Model name: Luke Skywalker type: Jedi name: Jabba type: Person 60

61 Edges with Different Edge Types Darth Vader instanceof instanceof Mace Windu Yoda Person knows born lives is a Warrior Planet Luke Skywalker is a is a Leia Organa instanceof Jedi Sith Jabba lives born Tatooine instanceof 61

62 REPRESENTING STRUCTURAL MODELS IN PROGRAMS 62

63 Programming Paradigms Programming paradigm: theoretical model of a programming language Structured programming (C, Pascal, Modula) o Organising variables into structures: struct/record 63

64 Programming Paradigms Objekt-oriented programming, OOP (C++, Java) o type: Class o instance: Object o attribute: Attribute field o operation: Methode o Visibility of attributes/methodes, data encapsulation, etc.: see Basics of Programming 2 o Pointer fields vs. nesting Terms: reference, composition, aggregation 64

65 OOP: Inheritance Design decision: Han Solo can never become a Warrior (has no lightsaber) Person gender: string Warrior saber_color : string Object name : string Planet orbital_period: int number_of_moons: int Jedi Sith 65

66 Textual representation o XML, JSON, Representing Models Graphical representation o UML, AADL, SysML, EMF, 66

67 Textual Representation XML (Extensible Markup Language) o standardised, universal technique for the definition of description languages o (human?) readable JSON (JavaScript Object Notation) o standardised notation for readable data exchange 67

68 XML-Example: Weather Web Service 68

69 JSON-Example: Google Maps API 69

70 Graphical Representation UML (Unified Modeling Language) o a universal modelling language o in SW development widely used AADL (Architecture Analysis & Design Language) o for describing of architectures SysML (Systems Modeling Language) o UML based general modellings language for system planing and modelling EMF (Eclipse Modeling Framework, Ecore) o for describing modelling languages 70

71 FURTHER ILLUSTRATIVE EXAMPLES 71

72 Illustration Structural Models Nested representation 72

73 Illustration Structural Models Frame structure Version IHL Type of Service Total Length Identification Flags Fragment Offset Time to Live Protocol Header Checksum Source Address Destination Address Options Padding