The Software Life Cycle

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Lydia Caldwell
6 years ago
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1 Inception Software Increment Communication Planning Production The Software Life Cycle Software Engineering Deployment Andreas Zeller Saarland University Modelling Elaboration Transition Construction Construction

3 A Software Crisis

4 Code and Fix (1950 ) Build first version Modify until client is satisfied Operate Retirement

5 Code and Fix: Issues No process steps no specs, docs, tests No separation of concerns no teamwork No way to deal with complexity

6 Code and Fix

7 Communicatio Waterfall Model (1968) n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

8 Communication Communicatio n project initiation

9 Communicatio Waterfall Model (1968) n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

10 Planning estimating scheduling tracking Planning

11 Communicatio Waterfall Model (1968) n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

12 Waterfall Model (1968) Modeling analysis design

13 Communicatio Waterfall Model (1968) n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

14 Waterfall Model Construction code test

15 Communicatio Waterfall Model (1968) n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

16 Deployment Deployment delivery support feedback

17 Communicatio Waterfall Model (1968) n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

21 Waterfall Model Communicatio n Real projects rarely follow a sequential project initiation flowplanning estimating scheduling tracking (1968) Hard to state all requirements explicitly Modeling No maintenance or evolution involved analysis design Customer must have patience Construction code Any blunder can be disastrous test Deployment delivery support feedback

22 Boehm s first law Errors are most frequent during requirements and design activities and are the more expensive the later they are removed.

23 Problem Cost Relative cost of problem per phase 30,0 22,5 15,0 7,5 0,0 Coding Unit test Component test System test Field

24 Incremental Model Features Increment #3 Increment #1 Communication project initiation requirements gathering Planning estimating scheduling tracking Increment #2 Communication project initiation requirements gathering Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback Modeling analysis design Construction code test Deployment delivery support feedback Communication project initiation requirements gathering Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback Time

25 Incremental Model Each linear sequence produces a particular increment to the software First increment typically core product; more features added by later increments Allows flexible allocation of resources

26 Prototyping Communication Quick Plan Deployment and Feedback Quick Design Prototype Construction

27 Prototypes Top Layer (GUI) Bottom Layer

28 Horizontal Prototype Top Layer (GUI) Bottom Layer

29 Prototypes Top Layer (GUI) Bottom Layer

30 Vertical Prototype Top Layer (GUI) Bottom Layer

31 Prototypes A horizontal prototype tests a particular layer (typically the GUI) of the system A vertical prototype tests a particular functionality across all layers Resist pressure to turn a prototype into a final result!

32 Spiral Model (1988) Communication Planning Modeling Deployment + Feedback Test Construction

33 Spiral Model System is developed in series of evolutionary releases Milestones for each iteration of the spiral Process does not end with delivery Reflects iterative nature of development

34 Unified Process (1999) Inception Software Increment Communication Planning Production Elaboration Deployment Modelling Transition Construction Construction

35 Software Increment Inception Inception Communication Planning Production Encompasses communication with user + planning Deployment Modelling Results in a set of use cases Architecture is just a tentative outline Transition Construction Elaboration Construction

36 Software Increment Production Elaboration Communication Refines and expands preliminary use cases Inception Planning Elaboration Provides architecture and initial Deployment design Modelling model Transition Construction Construction

37 Construction Inception Software Increment Builds (or acquires) Communication software components Planning Production according to architecture Completes design model Includes Deployment implementation, unit tests, acceptance tests Modelling Elaboration Transition Construction Construction

38 Software Increment Transition Inception Software given to end users for beta Communication testing Planning Production Feedback reports defects and changes Elaboration Deployment Modelling Transition Construction Construction

39 Production Inception Software Increment Production Software is deployed Problems are monitored Communication Planning Elaboration Deployment Modelling Transition Construction Construction

40 Software Increment Re-Iteration Inception Communication Planning Production Feedback results in new iteration for next Elaboration Deployment Modelling Transition Construction Construction

41 Unified Process Inception Software Increment Communication Planning Production Elaboration Deployment Modelling Transition Construction Construction

42 Unified Process Software Communication Planning IncrementDraws on best features of conventional Production process models Deployment Inception Emphasizes software architecture and design Modelling Integrates with UML modeling techniques (more on this later) Elaboration Transition Construction Construction

45 Manifesto for Agile Software Development (2001) Individuals and activities over processes and tools. Working software over comprehensive documentation. Customer collaboration over contract negotiation. Responding to change over following a plan..

46 What is Agile Development? Fast development? Hacking? Prototyping? Uncontrolled fun? Programmer heaven? Agility = ability to react to changing situations quickly, appropriately, and effectively. notice changes early initiate action promptly create a feasible and effective alternative plan quickly reorient work and resources quickly and effectively

47 Agile? Communicatio n project initiation Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback

48 Incremental Model Features Increment #3 Increment #1 Communication project initiation requirements gathering Planning estimating scheduling tracking Increment #2 Communication project initiation requirements gathering Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback Modeling analysis design Construction code test Deployment delivery support feedback Communication project initiation requirements gathering Planning estimating scheduling tracking Modeling analysis design Construction code test Deployment delivery support feedback Time

49 Credits: Prof. Bodik Agile Processes Time Waterfall Iterative Agile Processes Test Implement Design Analyse Scope

50 Agile vs. Plan-driven Agile Low criticality Senior developers Requirements change very often Small number of developers Culture that thrives on chaos Plan-driven High criticality Junior developers Requirements don't change too often Large number of developers Culture that demands order

51 What is an Agile Process? Difficult to predict which requirements will persist or change in the future. For many types of software, design and development are interleaved. Analysis, design, construction, and testing are not as predictable.

52 So, how to tackle unpredictability? make the process adaptable...

53 Extreme Programming (1999 ) Planning Design Test Coding Software Increment

54 Planning Planning Design In XP, planning takes place by Test means of stories Coding Each story captures essential behavior Software Increment

55 Extreme Programming Planning Design Test Coding Software Increment

56 Extreme Programming Planning Design Software Increment Design is made on the fly, using the KISS (keep it simple) principle Test Coding Virtually no notation besides CRC cards (object sketches) and spike solutions (prototypes)

57 Extreme Programming Planning Design Test Coding Software Increment

58 Coding Each Planning story becomes a unit test that Design serves as specification The program Test is continuously Coding Software Increment refactored to have the design match

59 Coding Planning To Design ensure continuous review, XP mandates pair Test Coding Software Increment

60 Extreme Programming Planning Design Test Coding Software Increment

61 Testing Planning Design Unit tests detect errors Test find Coding missing functionality measure progress Software Increment

62 Extreme Programming Planning Design Test The resulting prototypes result in Coding new stories Software Increment

63 Extreme Programming Planning Design Test Coding Software Increment

64 Spot the Difference

65 Scrum

66 Scrum An iterative and incremental agile software development method for managing software projects and product or application development. Small working teams to maximize communication, minimize overhead and maximize knowledge sharing. Adaptable to technical and business changes. Yields frequent software increments that can be inspected.

67 Scrum Development work and the people who perform it are partitioned into clean, low coupling partitions. Constant testing and documentation is performed. Ability to declare project done whenever required.

68 Scrum

69 Scrum Backlog: A prioritized list project requirements or features that provide business value. Sprints: Consists of work units that are required to achieve a defined backlog into a predefined time-box (usually 30 days). Scrum Meetings: Short 15 mins. meetings held daily by the scrum team. The Scrum master leads the meeting. Demos: Demonstrate software increment to the customer for evaluation.

70 Your Sprints Top Layer (GUI) 2. Top Layer 1. Core Use Case Bottom Layer 3. May-Haves

72 Summary

CMPT 275 Software Engineering

CMPT 275 Software Engineering Software life cycle 1 Software Life Cycle Sequence of processes completed as a software project moves from inception to retirement At beginning of project development, choose