Software Process Improvement.ppt

 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
Objectives

 Process and Product Quality
 Process classification
 Process measurement
 Process analysis and modelling
 Process change
 The CMMI process improvement framework
Topics covered

 Understanding existing processes and
introducing process changes to improve
product quality, 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 attributes can also
be the focus of improvement
Process improvement

Process attributes
Process
characteristic
Description
Understandability To what extent is the process explicitly defined and how easy is it t o
understand the process definition?
Visibility Do the process activities culminate in clear results so that the progress
of the processis externally visible?
Supportability To what extent can CASE tools be used to support the process
activities?
Acceptability Is t he defined process acceptable to and usable by the engineers
responsible for producing the software product?
Reliability Is the process designed in such a way that process errors are avoided or
trapped before they result in product errors?
Robustness Can the process continue in spite of unexpected problems?
Maintainability Can the process evolve to reflect changing organisational requirements
or identified processimprovements?
Rapidity How fast can the process of delivering a system from a given
specification be completed?

The Process Improvement Cycle

 Process measurement
• Attributes of the current process are
measured. These are a baseline for
assessing improvements.
 Process analysis
• The current process is assessed and
bottlenecks and weaknesses are identified.
 Process change
• Changes to the process that have been
identified during the analysis are introduced.
Process Improvement stages

 Process quality and Product quality are closely
related and process improvement benefits arise
because the quality of the product depends on its
development process.
 A good process is usually required to produce a
good product.
 For manufactured goods, process is the
principal quality determinant.
 For design-based activity, other factors are also
involved especially the capabilities of the designers.
Process and Product Quality

Principal Product Quality Factors
Product
quality
Development
technology
Cost, time and
schedule
Process
quality
People
quality

Quality factors
 For large projects with ‘average’ capabilities,
the development process determines
product quality.
 For small projects, the capabilities of the
developers is the main determinant.
 The development technology is particularly
significant for small projects.
 In all cases, if an unrealistic schedule is
imposed then product quality will suffer.

 Informal
• No detailed process model. Development team chose
their own way of working.
 Managed
• Defined process model which drives the development
process.
 Methodical
• Processes supported by some development method such
as the RUP.
 Supported
• Processes supported by automated CASE tools.
Process classification

Process applicability

 Process used should depend on type of
product which is being developed
• For large systems, management is usually the principal
problem so you need a strictly managed process;
• For smaller systems, more informality is possible.
 There is no uniformly applicable process which
should be standardised within an organisation
• High costs may be incurred if you force an inappropriate
process on a development team;
• Inappropriate methods can also increase costs and lead
to reduced quality.
Process choice

 Wherever possible, quantitative process data
should be collected
• However, where organisations 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

 Time taken for process activities to be
completed
• E.g. Calendar time or effort to complete an
activity or process.
 Resources required for processes or
activities
• E.g. Total effort in person-days.
 Number of occurrences of a particular event
• E.g. Number of defects discovered.
Classes of process measurement

 Goals
• What is the organisation trying to achieve? The
objective of process improvement is to satisfy
these goals.
 Questions
• Questions about areas of uncertainty related to
the goals. You need process knowledge to
derive these.
 Metrics
• Measurements to be collected to answer the
questions.
Goal-Question-Metric Paradigm

Process Analysis and Modelling
 Process analysis
• The study of existing processes to understand
the relationships between parts of the process
and to compare them with other processes.
 Process modelling
• The documentation of a process which records
the tasks, the roles and the entities used;
• Process models may be presented from
different perspectives.

 Study an existing process to understand its
activities.
 Produce an abstract model of the process.
You should normally represent this
graphically. Several different views (e.g.
activities, deliverables, etc.) may be required.
 Analyse the model to discover process
problems. This involves discussing process
activities with stakeholders and discovering
problems and possible process changes.
Process analysis and modelling

 Published process models and process
standards
• It is always best to start process analysis with an existing
model. People then may extend and change this.
 Questionnaires and interviews
• Must be carefully designed. Participants may tell you what
they think you want to hear.
 Ethnographic analysis
• Involves assimilating process knowledge by observation.
Best for in-depth analysis of process fragments rather
than for whole-process understanding.
Process analysis techniques

Process model elements 1
Activity
(shown as a round-edged
rectangle with no drop
shadow)
An activity has a clearly defined objective, entry and exit
conditions. Examples of activities are preparing a set of test data to
test a module, coding a fu nction or a module, proof-reading a
document, etc. Generally, an activity is atomic i.e. it is the
responsibility of one person or group. It is not decomposed into sub-
activities.
Process
(shown as a round-edged
rectangle with drop
shadow)
A p rocess is a set of activities which have some coherence and
whose objective is generally agreed within an organisation.
Examples of processes are requirements analysis, architectural
design, test planning, etc.
Deliverable
(shown as a rectangle with
drop shadow)
A deliverable is a tangible output of an activity that is predicted in a
project plan.
Condition
(shown as a parallelogram)
A condition is either a pre-condition that must hold before a process
or activity can start or a post-condition that holds after a process or
activity has finished.

Process model elements 2
Role
(shown as a circle with
drop shadow)
A role is a bounded area of responsibility. Examples of roles might
be configuration manager, test engineer, software designer, etc. One
person may have several different roles and a s ingle role may be
associated with several different people.
Exception
(not shown in examples
here but may be
represented as a double
edged box)
An exce ption is a description of how to modify the process if some
anticipated or unanticipated event occurs. Exceptions are often
undefined and it i s left to the ingenuity of the project managers and
engineers to handle the exce ption.
Communication
(shown as an arrow)
An interchange of information between people or between people
and supporting computer systems. Commu nications may be
informal or formal. Formal communications might be the approval
of a deliverable by a p roject manager; informal communications
might be the interchange of electronic mail to resolve ambiguities in
a document.

The module testing activity

Activities in module testing

Process exceptions
 Software processes are complex and process
models cannot effectively represent how to handle
exceptions:
• Several key people becoming ill just before a critical
review;
• A breach of security that means all external
communications are out of action for several days;
• Organisational reorganisation;
• A need to respond to an unanticipated request for new
proposals.
 Under these circumstances, the model is suspended
and managers use their initiative to deal with the
exception.

Process change
 Involves making modifications to existing
processes.
 This may involve:
• Introducing new practices, methods or
processes;
• Changing the ordering of process activities;
• Introducing or removing deliverables;
• Introducing new roles or responsibilities.
 Change should be driven by measurable
goals.

The Process Change process

Process change stages
 Improvement identification.
 Improvement prioritisation.
 Process change introduction.
 Process change training.
 Change tuning.

The CMMI framework
 The CMMI framework is the current stage of work
on process assessment and improvement that
started at the Software Engineering Institute in the
1980s.
 The SEI’s mission is to promote software technology
transfer particularly to US defence contractors.
 It has had a profound influence on process
improvement
• Capability Maturity Model introduced in the early 1990s.
• Revised maturity framework (CMMI) introduced in
2001.

Process capability assessment
 Intended as a means to assess the extent to
which an organisation’s processes follow
best practice.
 My providing a means for assessment, it is
possible to identify areas of weakness for
process improvement.
 There have been various process
assessment and improvement models but
the SEI work has been most influential.

 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
The SEI capability maturity model

Problems with the CMM
 Practices associated with model levels
• Companies could be using practices from different levels
at the same time but if all practices from a lower level
were not used, it was not possible to move beyond that
level
 Discrete rather than continuous
• Did not recognize distinctions between the top and the
bottom of levels
 Practice-oriented
• Concerned with how things were done (the practices)
rather than the goals to be achieved.

The CMMI model
 An integrated capability model that includes
software and systems engineering capability
assessment.
 The model has two instantiations:
• Staged where the model is expressed in terms
of capability levels;
• Continuous where a capability rating is
computed.

CMMI model components
 Process areas
• 24 process areas that are relevant to process capability
and improvement are identified. These are organized into
4 groups.
 Goals
• Goals are descriptions of desirable organizational states.
Each process area has associated goals.
 Practices
• Practices are ways of achieving a goal - however, they
are advisory and other approaches to achieve the goal
may be used.

CMMI Process Areas (1)
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 (2)
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
Goal Process area
Corrective actions are managed to
closure when the projectÕ
s performance
or results deviate sign ifi cantly from the
plan.
Specifi c goal in Project
Monitoringand Control
Actual performance and progress of the
project is monitored against the project
plan.
Specifi c goal inproject
monitoring and control
The requirements are analysed and
validated and a definitionof the required
func tionality is developed.
Specifi c goal in
requirements
development.
Root causes ofde fects and other
problems are systematically determined.
Specifi c goal incausal
analysis and resolution.
The process is institutionalised as a
defined process.
Gene ric goal

CMMI Practices
Practice Associated goal
Analyse derived requirements to ensure that they are
necessary and sufficient
Validate requirements to ensure that the resulting
product will perform as intended in the userÕs
environment using multiple techniques as
appropriate.
The requirements are analysed and
validated and a definition of the
required functionality is developed.
Select the defects and other problems for analysis.
Perform causalanalysis of selected defects and other
problems and propose actions to addressthem.
Root causes of defects and other
problems are systematically determined.
Establish and maintain an o rganisational policy for
planning and performing the requirements
Assign responsibility and authority for performing
the process,developing the work products and
providing the services of the requirements
The process is institutionalised as a
defined process.

CMMI Assessment
 Examines the processes used in an organization
and assesses their maturity in each process area.
 Based on a 6-point scale:
• Not performed;
• Performed;
• Managed;
• Defined;
• Quantitatively managed;
• Optimizing.

The Staged CMMI model
 Comparable with the software CMM.
 Each maturity level has process areas and
goals. For example, the process areas
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.

The Staged CMMI model

Institutional practices
 Institutions operating at the managed level
should have institutionalized practices that
are geared to standardization.
• Establish and maintain policy for performing the
project management process;
• Provide adequate resources for performing the
project management process;
• Monitor and control the project planning
process;
• Review the activities, status and results of the
project planning process.

The Continuous CMMI model
 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
5.
 The advantage of a continuous approach is that
organizations can pick and choose process areas to
improve according to their local needs.

A Process Capability profile
Project monitoring
and control
Supplier ag reement
management
Risk
management
Configuration
management
Requirements
management
V
erification
V
alidation
1 2 3 4 5

 Process improvement involves process analysis,
standardisation, measurement and change.
 Processes can be classified as informal, managed,
methodical and improving. This classification can be
used to identify process tool support.
 The process improvement cycle involves process
measurement, process analysis and process
change.
 Process measurement should be used to answer
specific process questions, based on organisational
improvement goals.
Key points

 The three types of process metrics used in the
measurement process are time metrics, resource
utilisation metrics and event metrics.
 Process models include descriptions of tasks,
activities, roles, exceptions, communications,
deliverables and other processes.
 The CMMI process maturity model integrates software
and systems engineering process improvement.
 Process improvement in the CMMI model is based on
reaching a set of goals related to good software
engineering practice.
Key points

Software Process Improvement.ppt

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