T76.3601 Introduction to Software Engineering - · PDF fileAB H E L S IN K I U N IV E R S IT Y O F T E C H N O L O G Y T-76.3601 – Introduction to Software Engineering ... • ISO

AB HELSINKI UNIVERSITY OF TECHNOLOGY

T-76.3601 – Introduction to Software Engineering

The Software Process

http://www.soberit.hut.fi/T-76.3601/

Casper [email protected]

AB HELSINKI UNIVERSITY OF TECHNOLOGY Casper Lassenius

Practicalities

• Registration closed

• First course email sent

• Slides published weekly on the schedule page


Software Engineering?

1. The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, that is, the application of engineering to software

2. The study of approaches in (1)

(IEEE Computer Society)


These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005

a “quality” focus

process model

A Layered Technology

Software Engineering

methods

tools


Software Process?• Process

• Webster: 1. A continuing development involving many changes. 2. A particular method for doing something, usually involving a number of steps or operations

• IEEE: a sequence of steps performed for a given purpose

• Software Process

• CMM(I): a set of activities, methods, practices and transformations that people use to develop and maintain software and the associated products

• Simply: the way an organization develops software


Knowledge,Skills, Needs,Motivation

Tools, Methods, Facilities,

Environment

Practices,Procedures,Instructions

Structure,Culture,Management,

Decision making

Leavitt’s Organizational Diamond

Structure

Technology

Process People

Adapted from Leavitt, H.J. Applied organizational change in industry: Structural, technological and humanistic approaches. Handbook of Organizational. J.G. March. Chicago, Rand McNally. 1965



A Process Framework

• Umbrella activities

• Framework activities

• work tasks (activities)

• work products

• milestones & deliverables

• QA checkpoints



Framework Activities• Communication

• Planning

• Modeling

• Analysis of requirements

• Design

• Construction

• Code generation

• Testing

• Deployment

• Retirement



Umbrella activities• Software project management

• Formal technical reviews

• Software quality assurance

• Software configuration management

• Work product preparation and production

• Reusability management

• Measurement

• Risk management



The Process Model: Adaptability• the framework activities will always be applied on

every project ... BUT

• the tasks (and degree of rigor) for each activity will vary based on:

• the type of project

• characteristics of the project and the project team

• common sense judgement; concurrence of the project team



Process Patterns• Process patterns define a set of activities, actions,

work tasks, work products and/or related behaviors

• A template is used to define a pattern

• Typical examples:

• Customer communication

• Analysis

• Requirements gathering

• Reviewing a work product

• Design model


Major Approaches to Software Process Improvement

• Personal Software Process (PSP)

• Team Software Process (TSP)

• Reference Model & Assessment

• SEI IDEAL

• SEI CMM(I)

• ISO 15504 (SPICE)

• Process Modeling and Definition

• ISO 9000

• Quality Improvement Paradigm & Experience Factory


The SEI Software Process Frameworks


Personal Level Process Improvement



Personal Software Process (PSP)• Recommends five framework activities

• Planning

• High-level design

• High-level design review

• Development

• Postmortem

• stresses the need for each software engineer to identify errors early and as important, to understand the types of errors


The Personal Software Process (PSP)

• Software engineers are poor at producing high-quality products to schedule and specifications

• The PSP helps individual engineers...

• plan

• track

• measure, and

• improve

• ...their own software processes


PSP Principles

• Engineers are individuals that must plan their work based on personal data

• To improve, personal measurement is needed

• To achieve quality, personal responsibility is important

• Bugs should be found and corrected as early as possible

• It is more efficient to prevent bugs than to find and correct them

• The right way is the fastest and cheapest way to do a job


PSP Training Path


The PSP Process Structure


A PSP Process Script


Time Recording Log


Defect Recording Log


Project Plan Summary


Experiences with the PSP (1/3)


PSP Experiences (2/3)


PSP Experiences (3/3)


Comments on the PSP• Brings discipline to personal software engineering

• Lots of work!

• needs support tools

• forms, forms, forms...

• Demands strict discipline

• Statistics needed sometimes quite involved

• Not very widely adopted – at least yet

• Worth trying – and adopting (?)

• I don’t know any coder who uses the PSP faithfully...


Summary• There is a lack of models dealing with personal level

software process improvement

• PSP aims at improving the way individual software developers perform their work

• The PSP provides a framework, methodology and supporting forms to help the developers

• The PSP is not (yet?) widely adopted, but the empirical data obtained show that it can provide improvements on many important dimensions

• For more information, get one of the books or surf to the SEI website: http://www.sei.cmu.edu/


Team Level Process Improvement


SPI at the Team Level• Lack of assessment / improvement models

• Several prescriptive models

• TSP

• Agile software development models

• XP

• Scrum

• ...



Team Software Process (TSP)

• Each project is “launched” using a “script” that defined the tasks to be accomplished

• Teams are self-directed

• Measurement is encouraged

• Measures are analyzed with the intent of improving the team process

• Relies on the PSP


TSP Roles

• Team Leader

• Development manager

• Planning manager

• Quality / Process manager

• Support manager


Experiences with the TSP (1/2)


TSP Experiences (2/2)



Process Assessment and Improvement

Software Process

Software ProcessAssessment

is examined by identifies capabilitiesand risk of

identifiesmodifications to

Software ProcessImprovement

CapabilityDetermination

leads to leads to

motivates



Process Assessment• The process is assessed to ensure that it meets a set

of process criteria that is believed to be essential for successful software engineering

• Many assessment options are available

• SCAMPI

• CBA IPI

• SPICE (ISO 15504)

• ISO 9001:2000


Process Assessment

• A disciplined evaluation of an organization’s software processes against a reference process model

• Different modes

• Official appraisal

• Self-assessment

• Different uses

• Process improvement

• Subcontractor evaluation


Organizational Level Process Improvement


SEI’s IDEAL

Stimulus forimprovement

Set Context& Establish

Sponsorship

EstablishImprovementInfrastructure

Appraise &Characterise

Current Practice

DevelopRecommendations

& Document Phase Results

Set Strategy& Priorities

Establish ProcessAction TeamsPlan Actions

DefineProcesses

& Measures

Plan & Execute

Pilots

Plan, Execute & Track

Installation

Document& AnalyseLessons

ReviseOrganisational

Approach

Acting

Establishing

Diagnosing

Leveraging

Initiating

SEI-95-

TR-001


SW–CMM• A strategy for improving the software process

• Put forward in 1986 by the SEI

• Fundamental idea:

• Improving the software process leads to

• Improved software quality

• Delivery on time, within budget

• Improved management leads to

• Improved techniques

• Five levels of “maturity” are defined

• Organization advances stepwise from level to level


CMM Summary


The CMM Maturity Levels


Key Process Areas• There are key process areas (KPAs) for each level

• Level 2 KPAs include:

• Requirements management

• Project planning

• Project tracking

• Configuration management

• Quality assurance

• Higher level areas attack same problems in different ways than lower ones

• Level 2: Detection and correction of faults

• Level 5: Prevention of faults


Impact of Process

Maturity


The CMMI

• The CMMI defined each process area in terms of “specific goals” and the “specific practices” required to achieve these goals

• Specific goals establish the characteristics that must exist if the activities implied by a process area are to be effective

• Specific practices refine a goal into a set of process-related activities


Process Improvement Data (contd)

Results of 34 Motorola projects


ISO 9000

• Set of five standards for industrial activities

• ISO 9001 for quality systems

• ISO 9000-3, guidelines to apply ISO 9001 to software

• Not process improvement

• Stress documenting the process and following and improving the documented process

• Emphasis on measurement and metrics


ISO9000 Quality System

Quality Systemauditsmgmt

reviews

Sustainingchange,

identifying new

Implementingchange,

sustaining commitment

Quality SystemHandbook

assessinglearning

Juha Rikkilä, Nokia


Summary• Two basic approaches at the organizational level

• Assessment model-based improvement

• CMM(I)

• ISO-15504 (SPICE)

• Bootstrap

• ...

• Measurement and modeling based

• Experience factory

• (ISO 9000 series of standards)

• ...



The Primary Goal of Any Software Process: High Quality

• High quality = project timeliness

• Why?

• less rework


Questions?

Documents

T76.3601 Introduction to Software Engineering - · PDF fileAB H E L S IN K I U N IV E R S IT Y O F T E C H N O L O G Y T-76.3601 – Introduction to Software Engineering ... • ISO