Lecture 1

Question 1

Software Engeneering

Answer 1

1. engeneering discipline concerned with all aspects of software production (early stages of system specifications –> maintenance)
2. Concerned with professional software development

Question 2

SE Activities

Answer 2

Software Specification
Software Development
Software Validation
Software Evolution

Question 3

Software Specification

Answer 3

Specification of steps, rules, processes to build software

Question 4

1968

Answer 4

Software engeneering started as a tem with the objective to adress the software crisis caused by individual aproaches to development not scaling up to complex systems

Question 5

Software Validation

Answer 5

testing the software

Question 6

Sfotware Development

Answer 6

development of tools, framerorks…

Question 7

Software Evolution

Answer 7

Management of the software development over its lifetime

Question 8

Issues of Software

Answer 8

Heterogeneity - different types of computer and devices for distributed software
Bussines/Social change - software needs to respond well to quick changes
Security, Trust, Privacy - we must trust the software as it is ubiquitous

Question 9

Software Engeneering Fundamentals

Answer 9

1. Software should be developed using a managed and understood process
2. Dependability and performance - important for all kinds of systems
3. Software specification and requirements need to be well understood
4. Reuse software already deployed where applicable

Question 10

Software Engeneering Process (definition)

Answer 10

A structured set of activities required to develop a software system
(Process: series of actions or steps taken to achieve a particular end)

Question 11

SEP Activities

Answer 11

1. Specification - what software does
2. Design - how it does it
3. Implementation
4. Test and validation
5. Maintenance and Evolution - changing sofotware over time according to customer

Question 12

Software Process Model

Answer 12

Abstract representation of a process. Is composed of:
- Activities: what steps are defined by the model
- Products: outcomes of a process activity
- Roles: responsibilities of the people involved
- Pre and Post Conditions: statements true before and after an activity has been enacted or a product produced

Question 13

Types of Software Process Models

Answer 13

Plan Driven - All activities are planned in advance and progress is measured against set plam
Agile - Planning is incremental. Easier to change the process to reflect change in requirements

Question 14

Waterfall Model (general)

Answer 14

Plan Driven, Sequential and separate activities.

Question 15

Reuse Oriented SE

Answer 15

Software is assembled from existing components. Plan driven/agile

Question 16

Waterfall Steps (general)

Answer 16

Analysis - requirements and specifications
Design - Solution proposal and description
Implementing and unit testing - coding and testing
Integration, system testing and deployment
Maintenance and Evolution
(one after another)

Question 17

Waterfall: Analysis

Answer 17

Establishes required functionality and contraints on the software operation and dev.
Requirements engeneering process:
- Feasability study
- Requirements elicitation and analysis
- Requirements specification
- Requirements validation

Question 18

Waterfall: Design

Answer 18

Design a solution meeting the requirements specification.

Question 19

Waterfall: Implementation

Answer 19

Translate the design into executable program. Design and implementation are often interleaved

Question 20

Waterfall: Integration, Testing, Deployment

Answer 20

Verification and validation - the software conforms to its specifications and meets requirements
Testing: Execute system with test cases.

Question 21

Waterfall: Maintenance and Evolution

Answer 21

Solve bugs and other issues, improve existent functionality, extend software with additional features

Question 22

Waterfalll: Advantages and Limitations

Answer 22

+ Applied where requirements are stable. Useful for coordinating large projects with development on several sites. Easy to follow progress
- Does not cope well with changes in the requirements and is not flexible.
Suitable for:
- Embedded systems
- Critical Systems (need for safety and security)
- Large Software Systems

Question 23

Incremental Development

Answer 23

Activities are interleaved. Can be plan driven or agile

Objective: Cope with changes

System is develops in increments, evaluated (by user/customer proxy) before proceeding.

Requirements are prioritized (high priority adressed early). During dev, req are frozen and later adressed.

Question 24

Incremental Delivery

Answer 24

Deploy an increment for use by end-users –> more realistic evaluation about practical use.

Question 25

Incremental Development Advantages and Limitations

Answer 25

+ Customer value is delivered with each increment and functionality is available earlier. Early increments can help elicit requirements for later increments. Low risk of project failure. Highest priority functionality receives the most testing - Process is not visssible. Structure degrades as increments are added. Hard to identify common facilities for all increments.

Question 26

Bohem's Spiral Model

Answer 26

Loop in spiral = phase in process No fixed phases, loops are chosen depending on what is required Risks are explicitly assessed and resolved throughout the process

Question 27

Spiral Model Sectors

Answer 27

Objective Setting Risk assessment and reduction Development and validation Planning - project is reviewed, next phase is planned

Question 28

Spiral Model Usage

Answer 28

Introduced iteration and risk-driven approach to development in software processes Model rarelly used in practice

Question 29

Reuse Oriented SE

Answer 29

reuse of available software. Systems are integrated from existing components or commercial off the shelf systems. Standard approach for building many types of bussines systems