SOFTWARE PROCESS IMPROVEMENTcsevgi.bilkent.edu.tr/courses/ctis359/week11.pdf · PROCESS AND PRODUCT...

CTIS 359 Principles of

Software Engineering

SOFTWARE PROCESS

IMPROVEMENT

Cüneyt Sevgi CTIS 359 Fall 07-08

Today’s Objectives•To explain the principles of software process improvement

•To explain how software process factors influence software quality and productivity

•To explain how to develop simple models of software processes

•To explain the notion of process capability and the CMMI process improvement model

•To intoduce ISO/IEC 15504 international standard for process assessment


Software Quality & Process

Improvement

Quality of the development

process Quality of the software

product

SPI (Software Process Improvement)

is one way of enhancing the quality of

the software


What is Process Improvement?•Understanding existing processes and introducing process changes to improve product quality (reduce the # of defects delivered)

•ALSO reduce costs, or accelerate schedules.

•Most process improvement work so far has focused on defect reduction. This reflects the increasing attention paid by industry to quality.

•However, other process (like products attributes in the

previous lectures) attributes can also be the focus of improvement.


PROCESS ATTRIBUTES (or characteristics)

Pr oce ss

cha rac teristic

D escr iption

U nder standa bil ity To w hat ex ten t is the p roce ss exp lic itly defined an d how ea sy is it t o

under stan d t he p roc ess de fin ition?

V isib ility D o the process ac tiv it ies cu lmi na te in clea r results so that the p rogress

of the process is ex ter nally vis ib le?

Supportab il ity To w hat ex ten t can C A SE too ls be us ed to support the p roce ss

ac tiv it ies?

A cce p tab ility Is t he defin ed p roce ss acce p tab le to and us ab le by the enginee rs

responsible for p roduci ng the s oftw are p roduct?

Reliabi lity Is t he p roce ss designed in such a w ay that process errors are avoide d o r

trapped b efore the y result in p roduc t errors ?

Robus tness Can the proc ess cont inue in sp ite o f unex pect ed p rob le ms ?

M ain taina b ility Can the proc ess evolve to re flect cha nging org an is at ional requirem ents

or ide n tified p rocess imp rovem en ts?

Rapid ity H ow fast can the pro ce ss o f de liv ering a sys tem from a given

speci fic a tion be co mp le ted ?

Not possible to OPTIMIZE ALL attributes SIMULTANEOUSLY

e.g., Rapidity vs Visibility


Software Process Improvement

NOT simply adopt particular method,

tool, or model of process used elsewhere.

COMMON factors + LOCAL

ORGANIZATIONAL factors


Process Improvement Cycle


PROCESS IMPROVEMENT

STAGES

•Process measurement

•Attributes of the current product or project are measured. These are a baseline for assessing improvements.

•Process analysis

•The current process is assessed and bottlenecksand weaknesses are identified.

•Process change

•Changes to the process that have been identified during the analysis are introduced


PROCESS AND PRODUCT

QUALITY

•SPI is based on the assumption that “the quality of the product depends on its development process”.

•A good process is usually required to produce a good product.

•For manufacturing Industry , process is the principal quality determinant.

•W. E. Deming+ (others) introduced the idea of SPC*.

•SPC: “Reduce the # of product defects by PI until it is REPEATABLE.”

•For design-based activity, other factors are also involved especially the capabilities of the designers.


*SPC = Statistical Process Control

Deming+ = An American Engineer

Principal Product Quality Factors

In manufacturing, productprocess

relationship is obvious.

However, for software products, (like other

intellectual products e.g., book, films) quality

depends on its design.

Hence, 4 main factors affect product

quality


Principal Product Quality Factors (Cont.)

Product

quality

De velopment

technol o gy

Cost, time and

schedule

Process

quality

People

quality

Influence of these factors depend size and type of the project

Ex: For large projects

Ex: For small projects


PROCESS IMPROVEMENT

STAGES


•Process analysis

•Process change


PROCESS MEASUREMENT

•Process Measurements: are QUANTATIVE data about the software process.•Process Measurements can be used to assess whether the efficiency of a process has been improved.•Personal process (PSP) small-scale•TSP


PREDICTOR AND CONTROL

METRICS

Process metric: average time required

to repair reported defectProduct metric: average length

of identifiers in a program

For SPI, you should

measure product quality

as well


PROCESS MEASUREMENT

Wherever possible, quantitative process data should be collected.

◦ However, where organizations do not have clearly defined process standards this is very difficult as you don’t know what to measure. A process may have to be defined before any measurement is possible.

Process measurements should be used to assess process improvements.

◦ But this does not mean that measurements should drive the improvements. The improvement driver should be the organizational objectives.


PROCESS MEASUREMENT

3 classes of process metric:

1. The time for a particular process to be

completed e.g., t spent for process X

2. The resources required for a particular

process e.g., travel costs, total effort

3. The # of occurrences of a particular

event e.g., # of defects discovered in the code

inspection


PROCESS IMPROVEMENT

STAGES


•Process analysis and

modeling

•Process change


PROCESS ANALYSIS AND

MODELING

•Process analysis

•The study of existing processes to understand the relationships between parts of the process and to compare them with other processes.

•Process modeling

•The documentation of a process which records the tasks, the roles and the entities used;

•Process models may be presented from different perspectives.

•Simplifies views of software processes

•Activities

•Outputs, Inputs


PROCESS IMPROVEMENT

STAGES


•Process analysis and

modelling

•Process change


PROCESS CHANGE

•Involves making modifications to existing processes.•This may involve:

•Introducing new practices, methods or tools;•Changing the ordering of processactivities;•Introducing or removing deliverables;•Introducing new roles or responsibilities.

•Change should be driven by measurable goals.


PROCESS CHANGE (Cont.)

•If you are a project manager/director, •you have to be sensitive to the feelings of the people in your team when introducing process change

•People feel threatened by change and concerned that

•lose their jobs

•unable to cope with the new process

•Solution: User involvement


CMM(I) PI FRAMEWORK

•Mid-1980s Software Engineering Instituteinitiated a study of ways assessing capabilities of the contractors

•Mid-1990s Capability Maturity Model

•Tremendous impact on SWE industry

•CMM the early 1990s.

•P-CMM

•SPICE (assesment+PI)

•Revised maturity framework (CMMI) introduced in 2001.


CMM(I) PI FRAMEWORK (Cont.)

•CMM the early 1990s.

•Scope: Software and Systems Engineering

•P-CMM

•CMM + People

•CMMI introduced in 2001

•Integrates other engineering models

•2 Instantiations•Staged

•Continuous


CMMI

Complex but simlified version

1. Process Areas (4 Groups of 24 PAs)

2. Goals: desirable state

3. Practices: ways of achieving goals


CMMI PROCESS AREAS 1&2

Process management Organisational process definition

Organisational process focus

Organisational training

Organisational process performance

Organisational innovation and deployment

Project management Project planning

Project monitoring and control

Supplier agreement management

Integrated project management

Risk management

Integrated teaming

Quantitative project management


CMMI PROCESS AREAS 3&4

Engineering Requirements management

Requirements development

Technical solution

Product integration

Verification

Validation

Support Configuration management

Process and product quality management

Measurement and analysis

Decision analysis and resolution

Organisational environment for integration

Causal analysis and resolution


CMMI Goals Example


G oa l P roce ss area

Co rrec tive ac tions ar e m anag ed to

closure when the p rojec t’ s pe rfo rm ance

or resu lts dev iate sign ifi can tly from the

plan .

Spec ifi c go al in Pr ojec t

Mon it oring and Con trol

Ac tua l pe rfo rm ance and prog ress of t he

projec t is m on it or ed ag ain st the proj ect

plan .

Spec ifi c go al in p rojec t

m on it or ing and cont rol

T he requ ir em en ts are an al ysed and

va li da ted and a de finiti on o f the requ ired

func tiona li ty is deve loped .

Spec ifi c go al in

requ irem ents

deve lop m en t.

Roo t cau ses of de fec ts and other

prob lem s ar e sys tem atica ll y de term ined.

Spec ifi c go al in c ausa l

ana lysis and resolu tion .

T he p roce ss is in stit ut ion a lis ed as a

de fined p roce ss.

Gene ric goa l

CMMI Practices Example


Pr actice Ass oc iated goal

A na lyse de rived requ irem en ts to ens ure tha t the y are

nece ssary an d su ffic ien t

V al ida te req u irem ents t o en su re that the r esulting

product w ill perf orm as inten ded in the us er ’s

environm ent us ing m ultip le tec hniques as

appropriat e .

The req u irem ents are ana lyse d a nd

vali dated an d a defin it ion o f the

req u ired func tiona li ty is d ev e lo ped .

Sel ect the de fec ts and other p roblems for anal ysis.

Perform cau sa l a nalysis of s elect ed defect s an d o ther

problems and propos e act ions to address them .

Root ca us es of de fec ts and o ther

problems are sys tem atica lly de term ined .

Establ is h an d m ainta in an o rganisa tiona l polic y for

p la nning an d p erformi ng the requirem ents

deve lopm en t p roce ss .

Ass ig n r esponsibili ty an d au thority fo r perfor m ing

the p roce ss, de velop in g t he w ork p roduct s an d

providing the service s o f the req u irem ents

deve lopm en t p roce ss .

The p ro ce ss is ins titutiona lised as a

def ine d p roce ss .

CMMI (6 scales)

Not performed: goal goals associated with PA not satisfied

Performed: goal PA satisfied Managed: Documented plan resource

man. and process monitoring Defined: Measurements must be

collected and used for future projects Quantitatively Managed: Use SPC and

quantitative methods. Optimizing: Product and process

metrics are used for SPI


STAGED CMMI MODEL•Comparable with the software CMM.•5 levels•Each maturity level has process areas and goals. •E.g., The process area associated with the managed level include:

•Requirements management;•Project planning;•Project monitoring and control;•Supplier agreement management;•Measurement and analysis;•Process and product quality assurance.•Configuration Management


CMM STAGES

•Initial•Essentially uncontrolled

•Repeatable•Product management procedures defined and used

•Defined•Process management procedures and strategies defined and used

•Managed•Quality management strategies defined and used

•Optimising•Process improvement strategies defined and used


STAGED CMMI MODEL


CONTINUOUS CMMI MODEL

•No discerete levels for organization

•This is a finer-grain model that considers individual or groups of practices and assesses their use.

•The maturity assessment is not a single value but is a set of values showing the organizations maturity in each area.

•The CMMI rates each process area from levels 1 to 6.

•The advantage of a continuous approach is that organizations can pick and choose process areas to improve according to their local needs.


CONTINUOUS CMMI MODEL(Cont.)


Project monitor ing

and control

Supplier ag reement

management

Risk

management

Configuration

management

Requirements

management

Verificati on

Validat ion

1 2 3 4 5

ISO/IEC 15504•ISO 15504 was initiated in 1993 as the SPICE (Software Process Improvement and Capability determination) project.

•The project then moved into the International Organization for Standardization and the International Electro technical Commission (ISO/IEC)

•The principle of ISO/IEC 15504 is that the assessments of software process capability will yield results which are comparable.

•The goal of 15504 is to create a world standard that can be used to link assessment results to improvement actions.

•It allows different assessments models and methods (like CMMI) to be used.


KEY POINTS•Process improvement involves process analysis, standardization, measurement, and change.•Process models include descriptions of activities, sub-processes, and deliverables.•The CMMI process maturity model is an integrated process improvement model that supports both staged and continuous process improvement.


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