L4 - System Decomposition

Question 1

Filter

Answer 1

Processing Step

Question 2

8 Steps of System Design

Answer 2

1. Design Goal
2. Subsystem Decomposition
3. Concurrency
4. Hardware/Software Mapping
5. Persistent Data Management
6. Global Resource Handling
7. Software Control
8. Boundary Conditions

Question 3

Closed Architecture (Opaque Layering)

Answer 3

Layer can only call operations from layer below. Buschmann: ‘direct addressing’ - low coupling: more portable

Question 4

API

Answer 4

Application Programmer’s Interface (API) specifies the subsystem interface

Question 5

What is not explicitly shown in Communication Diagrams?

Answer 5

Labels + Roles + Multiplicities (Difference between Communication and Class Diagrams)

Question 6

Open Architecture (Transparent Layering)

Answer 6

Layer can call any operation. Buschmann: ‘indirect addressing’ - high coupling: higher performance

Question 7

Which architectural style should be used when considering systems with high coupling?

Answer 7

Model View Controller

Question 8

Problem Solving Heuristics

Answer 8

Understanding the problem + Devising a plan + Executing plan + Examining solution

Question 9

Process Flow MVC

Answer 9

1. View sends update to Controller
2. Controller updates Model
3. Model updates View

Question 10

View (MVC)

Answer 10

Subsystem that contains boundary objects (displaying information to user)

Question 11

Cohesion

Answer 11

Dependency and relation among classes. More interaction within their subsystem (high cohesion) = the better.

Question 12

Controller (MVC)

Answer 12

Subsystem between views and models (responsible for interacting with user & change mangement)

Question 13

Pipe

Answer 13

Connection between two processing steps

Question 14

Client-Server Architecture

Answer 14

Client (Input + Front End Processing) + Server (Data Management)

Question 15

‘Layer A calls layer B’

Answer 15

Runtime dependency

Question 16

MVC

Answer 16

Model View Controller decouples data access and data presentation.

Question 17

T.H.E. System (Dijkstra)

Answer 17

Selected Layer has no knowledge of higher layers (‘directed addressing’)

Question 18

‘Layer A depends on layer B’

Answer 18

Usage/Compile Time Dependency

Question 19

3-layered Architecture

Answer 19

Application consists of three hierarchically ordered layers.

Question 20

Design Goal

Answer 20

Identify functional and non-functional Design Goals. Stakeholders might have different needs than developers (trade-off)

Question 21

Communication Diagram

Answer 21

Class Diagram + Messages (sequential/conditional/concurrent)

Question 22

Subsystem Decomposition

Answer 22

Reduce the complexity of system while allowing change (high cohesion + low coupling)

Question 23

Coupling

Answer 23

Dependency among subsystems. Low coupling (subsystem interactions) desirable. Calling class should not know anything about internal variables (Principle of information hiding)

Question 24

3-tier Architecture

Answer 24

Closed Architecture + 3 Layers on 3 separate hardware nodes (web browser + web server + database)

Question 25

Service

Answer 25

Group of externally visible operations provided by a subsystem

Question 26

Model (MVC)

Answer 26

Subsystem that contains entity objects (responsible for application domain knowledge)