A maintainability enhancement procedure

International Journal of Software Engineering & Applications (IJSEA), Vol.6, No.4, July 2015
DOI : 10.5121/ijsea.2015.6403 29
A MAINTAINABILITY ENHANCEMENT PROCEDURE
FOR REDUCING AGILE SOFTWARE DEVELOPMENT
RISK
Sen-Tarng Lai
Dept. of Information Technology and Management, Shih Chien University,
Taipei, 104, Taiwan
ABSTRACT
In mobile communications age, environment changes rapidly, the requirements change is the software
project must face challenge. Able to overcome the impact of requirements change, software development
risk can be effectively decreased. In order to reduce software requirements change risk, the paper
investigates the major software development models and recommends the adaptable requirements change
software development. Agile development applied the Iterative and Incremental Development (IID)
approach, focuses on workable software and client communication. In software development, agile
development is a very suitable approach to handle the requirements change. However, agile development
maintenance existed many defects that include development documents control, user story inspection and
CM system. The maintenance defects of agile development should be improved. Analysing and collecting
the critical quality factors of agile development maintainability, in this paper proposes the Agile
Development Maintainability Measurement (ADMM) model. Based on ADMM model, the Agile
Development Maintainability Enhancement (ADME) procedure can be defined and deployed for reducing
the risk of requirements change.
KEYWORDS
Agile development, maintainability, requirements change, quality measurement, ADMM
1. INTRODUCTION
In software development process, it is necessary to face challenge of requirements change.
Software project must overcome the impact of requirements change to effectively reduce
development risk [1], [2], [3]. Requirements change often affects software development
operations. Requirements change makes the development flow need back to earlier development
phases for revising related artefacts. It not only need invest extra resource and cost, but also may
cause the schedule delay [1], [2]. In requirements change process, affected design and
development documents unable to effectively isolate, will increase software development risk. In
addition, affected design and development documents unable completely and correctly modify,
will greatly reduce project success ratio. There are many factors may affect the software project
failure. One of critical issues is software design and related documents can‘t immediately revise
and effectively adjust with the requirements change. For this, software development process must
have high adjustment capability and modification flexibility for reducing requirements changes
risk.

30
The paper discusses and surveys mutual relationship between the software development models
and user requirements. Because of the requirements change often is the critical factor to cause
project fail. Iterative and Incremental Development (IID) model has been widely used by many
software methodologies (ex. Unify process, Spiral model and Agile Process)[4] . Iterative
technology makes user requirements have many change opportunities. Incremental concept can
effectively decrease the requirements complexity. IID model can reduce the partial risk of
software requirements change. Agile development model is a new software development
methodology [5], [6], [7] that uses IID model to reduce the impact of requirements change [8],
[9]. Agile development model has high adaptability and high tolerability for requirements change.
In addition, agile development model uses IID to reduce the requirement complexity, refactoring
to increase the requirement modified flexibility, and do not rely on the documents can reduce
affected items of requirements change. In requirements change, agile development model greatly
decreases schedule delay, cost out of budget and quality unsatisfied requirement events,
requirements change risk can be effectively reduced. However, agile process neglects analysis
and design phase operations and development documents, emphasizes workable products, does
not pay attention to follow-up maintenance operations that are major shortages [5], [6], [7], [10].
In order to make up the disadvantages of agile development, development maintenance quality
should be enhanced. There are many development maintenance quality factors which include
development document system, user story (requirement item) inspection mechanism and
configuration management system may affect requirements change operations. For overcoming
the challenge of requirements change, in this paper, analysing and collecting the critical quality
factor of development maintenance. Based on the metric combination model, in this paper
presents the Agile Development Maintainability Measurement (ADMM) model. In ADMM
model, development document control, user story inspection mechanism and configuration
management system etc. qualities will be measured and combined. Based on ADMM model and
applied rule-based defects identification and improvement manner, the Agile Development
Maintainability Enhancement (ADME) procedure can be defined and developed for reducing the
risk of requirements change. In Section 2, surveys the critical factors of software project failure,
the relationship between system requirement and development models, and describes the
advantages of agile development. Many factors may affect maintenance process quality, in
Section 3, discusses maintenance process quality factors which are affected by requirements
change. In Section 4, proposes the ADMM model, and develops the rule-based maintenance
process quality defects identification and improvement manner. In Section 5, defines and deploys
the Agile Development Maintainability Enhancement (ADME) procedure. Finally, describes the
advantages of ADMM model and ADME procedure, and does a conclusions in Section 6.
2. REQUIREMENTS CHANGE RISK AND CRITICAL DEVELOPMENT MODELS
Requirements change is one of major critical factor to cause project fail. The section discusses the
more suitable development model for overcoming requirements change.
2.1. Critical Factors of Software Project Failure
According to the Standish group study report which investigated large volume software project,
the success rate of software project only approach one third [10], [11]. 80% failure software
projects suffer from the thorny problems which include cost over budget, schedule delay and not
compliance requirements. High failure risk of software project comes from the schedule delay,
insufficient budget and unfinished requirements etc. events [3], [12]. Four critical events are
major reason to cause the software project with high risk:

31
(1) In requirement phase, system analysts acquire and collect incomplete documents and
information to cause software system requirements existed the inconsistent, incomplete and
incorrect situations. Seriously impact the software system development follow operations.
(2) In software development process, requirements change, new technologies and operating
environment are innovated continuously. It causes the existing development plans can not
completely adapt to new situation.
(3) Entering development phases, the client proposed to adjust, modify or delete the existed
requirement items. Some new requirements are even required to append into the system.
These requirements changes will greatly impact to follow up software development
operations.
(4) Each phase operation of software development needs different resource which includes
developers, hardware devices, software tools and development environment. Resource
allocation that can't adjust to requirements change may increase software development risk.
Summary the above description, incomplete system requirements, technology and environment
evolution, client change requests and resource re-allocation are four major events of increasing
project risk (shown as Figure 1). These events often cause requirements change. In software
development process, the requirements change events can’t be avoided or excluded.
Requirements change is a critical reason of software project failure. Therefore, for reducing the
project failure ratio, software process should have high adaptability and maintainability to handle
many kinds of requirements change. It is because that new requirements of software system will
be continually proposed until system be terminated or phased out.
Figure 1. Four critical factors of software project failure
2.2. Advantages and Shortages of Agile Development
In 1967, the concept of software engineering was proposed and discussed in the NATO
international conference [13]. In the period, with the growth of information technology,
operational environment and user requirements, software development methodologies
continuously progress. From early Fix-code to recently Model-Driven Architecture (MDA) [14]
and agile development model about have a dozen development models. Most software
development models have high relationship with the user requirements. Water fall model defines
clear phase mission and very concerns the phase documents. The quality of requirement
documents can't reach correctness, completeness and consistency, development process will be
denied to enter the following phase. Recently proposed development models have modified
requirement specification style. In a time, it is not necessary describe all kinds and complete
requirement items. By iterative development model, user can provide the requirement items
incremental. Software development risk can be greatly reduced. Rapid prototyping model quickly
develops prototype product and becomes a well communication channel with user. The prototype
Software
Project
Failure
Resource re-
allocation
Requirement
change
New
technologies
Requirement
quality defects

32
can help recognize the incomplete, inconsistent or incorrect requirement specifications. Spiral
development model very concerns the development risk and has high flexibility. In development
process, spiral can adjust suitable development method for encountering different risks. However,
the development risk can't effective be improved or reduced, the spiral recommends to terminate
or abort software project. Each development model has an adjustment strategy for the user
requirements change. The adjustment strategy can't effectively reduce the software development
risks that will impact success ratio of software project.
In February 2001, seventeen software developers met at the Utah (ski resort) of USA for two days
and produced the Manifesto of the agile software development. Many of participants had
previously authored their own software development methodologies, including Extreme
programming, Crystal, and Scrum [4], [6], [9]. Agile software development proposes several
critical viewpoints:
(1) In development process, does not concern analysis and design phase operations and
documents.
(2) As soon as possible to enter programming phase, workable software is more practical than
development document.
(3) Support and provide high changeability software system.
(4) Enhance the cooperative relationship between developer and user, user can fully attend the
development team.
In time management side, agile software development applies time-boxing approach to control
process schedule [4], [9]. Requested software project must release a new version in two or three
weeks. Let client clearly understand the development progress and test, audit the requirement of
new version. In each day, a fifteen minutes stand up meeting is fixedly held to effectively reach
the fully communication between client and developers. In addition, agile process uses IID and
user stories [15] to reduce the requirement complexity, refactoring to increase the requirement
modified flexibility, non-document oriented can reduce the cost of requirements change. In
requirements change, agile development greatly decreases schedule delay, cost out of budget, and
quality unsatisfied user requirement situations, software requirements change risk can be
effectively reduced. However, agile process does not concern analysis and design phase
operations and documents, applies non-document oriented development, does not pay attention to
follow-up maintenance operation that are major shortages. The advantages and shortages of agile
software development process is shown as Figure 2. The shortages of agile development should
be improved or enhanced to effectively overcome the impacts of requirements change.
Figure 2. Advantages and shortages of agile development
Agile
Software
Development
Traceability Refactoring
CM &
Version Control
Iterative &
Incremental
Development
Communication
Analysis & Design
Documents

33
3. DEVELOPMENT MAINTAINABILITY
Software development model evolution has high correlation with user requirements. Can
appropriately handle user requirements, the software development risk can be reduced concretely.
3.1. Quality factors of development maintainability
Software development maintainability is a key point to affect change risk of user requirements. In
software development, the development documentation tasks, requirement items inspection
mechanism and Configuration Management (CM) system are critical activities of maintenance
quality. Development maintenance quality should consider the critical factors that described as
follows:
(1) Development documents control: In requirements change process, the documents quality is
critical factor to directly affect the effort of requirement changes. Agile development should
draw up a document review mechanism and consider follows three factors:
• Documents quality criteria: development documents must have correctness, completeness,
consistency and standard documentation format. Agile development should provide the
document review checklists to control documents quality. High quality documents can
reduce the impaction of personnel mobile.
• Documents review procedure: agile development needs draw up a useful and practical
review procedure to define the documents review steps and detailed tasks.
• Documents cross-reference table: document cross-reference tables is critical item to
concretely create the interconnection relationships and traceability.
(2) User story (requirement item) inspection: Ambiguous, complex, high coupling and low
cohesion requirement items often become the troubles of software development especially in
requirements change. Therefore, user story quality mechanism should consider follows three
factors:
• Clarity inspection: user stories are the discussion basis of software development. Clarity is
a necessary factor for user story discussion and communication. Qualified user story should
have high clarity to requirement description.
• Complexity inspection: requirement item complexity can be measured with size, logic
complexity [16] and data structure complexity [17]. Qualified user story should have low
logic and data structure complexity to requirement description.
• Modularity inspection: requirement items with high modularity can increase development
maintenance quality [4]. Qualified user story should have the low coupling and high
cohesion to requirement description.
(3) CM system: CM system can manage all kind development documents, control product
versions and documents cross-reference relationship [13]. Configuration management
mechanism should consider follows three factors:
• CM procedure: CM procedure: a well and practical CM procedure is used to manage the
related operations for documents check-in and check-out.
• Version control tools: CM system need combine the suitable and practical version control
tools to handle, record and storage the difference among the document versions.

34
• Change control procedure: for control requirement change, agile development should set up
a Change Control Board (CCB) to audit and evaluate change requests [13]. And identify
the affected development documents and artefacts in change operations.
The architecture of agile development maintenance quality factors is shown as Figure 3.
3.2. Quality factors collection and normalization
In CMMI, software process improvement is critical task for increasing software product quality.
Collecting and quantifying the critical software activities factors is first step to improve software
process quality. Each phase documents review and inspection activities can help collect the
quality factors of document cross-reference. For collecting useful factors, it is necessary to
develop a set of complete and clear inspection checklists to conduct the process audit activity.
Audit checklists can detect and identify the quality and incomplete defects of software process.
Software process audit can help collect the procedure quality factors of documents review,
qualified user story and configuration management. Procedure items and steps checklists can help
collect some the detailed tasks and criteria quality factors. Collecting documents review, user
story inspection and configuration management mechanisms quality factors are the necessary task
for quantifying the maintenance process quality.
Figure 3. The architecture of maintenance process quality factors
However, individual factor or measurement can only measure or evaluate the specific quality
characteristic. In order to effectively monitor and assess the maintenance process defects,
individual measurements should make the appropriate combination [19], [20], [21]. Two kind of
metric combination models are Linear Combination Model (LCM) [19], [20], [21] and Non-
Linear Combination Model (NLCM) [19], [20], [22]. NLCM has higher accuracy measurement
than LCM. However, LCM has high flexibility, more extensible and easy formulation than
NLCM (Shown as Table II). For this, in this paper, LCM is applied to maintenance quality
measurement. The different level development activities have different quality metrics be shown.
Therefore, before applying the linear combination model, the quality factors must be normalized.
The normalized value is between 0 and 1. The best quality quantified value approaches to 1 and
the worst quality approaches to 0.
CM System
Agile Development
Maintenance Quality Factors
Documents Quality
Criteria
Documents Review
Procedure
Documents Cross-
Reference Tables
Development
Documents Control
User Story
Inspection
CM Procedure
Version Control
Tools
Change Control
Procedure
User Story Clarity
Inspection
User Story Complexity
Inspection
User Story Modularity
Inspection

35
4. MEASUREMENT MODEL AND DEFECTS IDENTIFICATION
Enhancing maintenance process can effectively decrease the impact of requirements change and
concretely reduce the development risk of software project.
4.1. Maintainability measurement model
Maintenance process activities should consider three quantified quality that include documents
traceability, configuration management and requirement items changeability. Using the LCM, the
basic quality factors can be combined into the primitive metric, and then the related primitive
metrics can be combined into a quality measurement. Finally, combines with three critical quality
measurements and generates an agile development maintainability indicator. Four formulas
described as follows:
(1) Development Documents Control Quality Measurement (DDCQM) is combined document
review criteria, document review procedure and document cross-reference table three metrics.
The combination formula is shown as Equation (1):
DDCQM: Development Documents Control Quality Measurement
DQC: Document Quality Criteria W1: Weight of DQC
DRP: Document Review Procedure W2: Weight of DRP
DCRT: Document Cross-Reference Table W3: Weight of DCRT
DDCQM = DQC * W1 +DRP * W2 + DCRT * W3 W1 + W2 + W3 = 1 (1)
(2) User Story Inspection Quality Measurement (USIQM) is combined clarity, low complexity
and modularity three determination capabilities. The combination formula is shown as
Equation (2):
USIQM: User Story Quality Measurement
CDC: Clarity Determination Capability W1: Weight of CDC
CDC: Complexity Determination Capability W2: Weight of CDC
MDC: Modularity Determination Capability W3: Weight of MDC
USIQM = CDC * W1 + CDC * W2 + MDC * W3 W1+W2+W3=1 (2)
(3) Configuration Management System Quality Measurement (CMSQM) is combined CM
system, version control tool and change control procedure metric. The formula is shown as
Equation (3):
CMSQM: Configuration Management Quality Measurement
CMP: CM Procedure W1: Weight of CMP
VCT: Version Control Tools W2: Weight of VCT
CCP: Change Control Procedure W3: Weight of CCP
CMSQM = CMP * W1 + VCT * W2 + CCP * W3 W1+W2+W3=1 (3)
(4) Finally, combine DDQM, USQM, and CMQM into an Agile Development Maintainability
Indicator (ADMI). The formula is shown as Equation (4):
ADMII: Agile Development Maintainability Indicator
DDCQM: Development Documents Control Quality MeasurementW1: Weight of DDCQM
USIQM: User Story Inspection Quality Measurement W2: Weight of USIQM
CMSQM: CM System Quality Measurement W3: Weight of CMSQM
ADMI = DDCQM *W1 + USIQM *W2 +CMSQM * W3 W1 + W2 + W3 = 1 (4)
In agile development, CM system, user stories and development documents inspection activity
identified the factors which affect requirements change were collected and divided into 9 groups.
In first layer, 9 groups basic quality factor are combined into 9 quality metrics. In second layer, 9

36
quality metrics are combined into three quality measurements. In third layer, three quality
measurements are combined into an Agile Development Maintainability Indictor (ADMI). With
three layer combination formulas to generate an ADMI, the process is called an Agile
Development Maintainability Measurement (ADMM) model. The ADMM model architecture is
shown as Figure 4.
4.2. Rule-based maintenance quality defects identification
ADMI is a relative judgment mechanism and also a basis to identify problems or defects of
maintenance quality. In ADMM model, basic quality factors are combined into high level
measurement. High level quality measurements are combined into an ADMI. Therefore, if the
ADMI does not satisfy quality criterion, it represents maintenance process existed some related
defects and problems. According to the combination formulas, quality measurement mapping to
three major quality measurements and some quality factors. The affected development activities
and documents should be rigorously inspected to identify the problem or defect and propose the
corrective action. This paper proposed the rule-based improvement activities for increasing
maintenance quality of development, described as follows:
<Rule 1> IF ADMI does not satisfy "quality criterion"
THEN DDCQM, USIQM and CMSQM should be analysed to identify the problem and
defect of related documents or activities.
<Rule 2> IF DDCQM does not satisfy "quality criterion"
THEN document quality criteria, document review procedure and document cross-
reference table quality factors should be analysed to identify the defects of
related documents or activities.
<Action 1> Identify the activities and reasons to cause development document
management defects.
<Action 2> Confirm the defects revision or correction has accomplished.
<Rule 3> IF USIQM does not satisfy "quality criterion"
THEN clarity inspection, complexity inspection and modularity inspection quality
factors should be analysed to identify the defects of related documents or
activities.
<Action 1> Identify the activities and reasons to cause user story quality mechanism
defects.
<Rule 4> IF CMSQM does not satisfy "quality criterion"
THEN CM procedure, version control and tools, and cross-reference table quality
factors should be analysed to identify the defects of related documents or
activities.
<Action 1> Identify the activities and reasons to cause CM system defects.

37
Figure 4. Architecture of ADMM model
5. AGILE DEVELOPMENT MAINTAINABILITY ENHANCEMENT PROCEDURE
For overcoming the requirements change, the agile development should strengthen three major
shortages that include development documents control, user story inspection mechanism and CM
system. In this paper, the ADMM model is proposed for enhancing the maintainability of agile
development. Based on ADMM model, the Agile Development Maintainability Enhancement
(ADME) procedure is defined, deployed and shown as Figure 5. ADME procedure develops six
phases which are described as follows:
• Routine auditing phase: In order to understand and improve the maintenance process, agile
development should plan the routine auditing operation. Routine auditing can help inspection
maintenance activities and collect the influence factors.
• Factors collection phase: In auditing phase, critical maintenance quality factors should be
checked, collected and normalized to assist identify the defects of maintenance activities.
• Quality measurement phase: Based on the normalized quality factors and ADMM model, the
Agile Development Maintainability Indicator (ADMI) can be computed and generated for
identifying the quality defects.
• Defects identification phase: According to ADMI and acceptable quality criteria, the major
and minor defects of maintenance process can be identified.
Agile Development Maintainability Indicator
Development Document Control Quality Measurement
Document Quality Criteria
Document Review Procedure
Document Cross-Reference Table
CM System Quality Measurement
CM Procedure
Version Control Tools
Change Control Procedure
User Story Inspection Quality Measurement
Clarity Inspection
Low Complexity Inspection
Modularity Inspection

38
• Revision phase: Analysing the reasons of identified defects, agile development should develop
a revision plan to adjust the current quality activity or append the new quality activities for
enhancing agile development maintainability.
• Continuous Improvement phase: Finally, based on the environment and application change,
ADMM model should continuously be adjusted and modified for accomplishing the target of
quality continuous improvement.
Software development uses the agile development methodology and applies the ADMM model
enhancing its maintainability can concretely reduce software development risk. Agile
development enhanced maintainability can accomplish three major missions, description as
follows:
(1) Complete, correct and consistent development documents:
• Based on documents quality criteria, the development documents have a set of quality
regulations.
• Based on documents review procedure, the defects of development documents can be
identified and corrected.
• Based on documents cross-reference table, the cross-relationship of development
documents have high interconnection to enhance documents consistency, completeness and
maintainability.
(2) Clarity, low complexity and modularity user story:
• Based on clarity inspection, requirement items can increase the communication capability
of requirements change.
• Based on complexity inspection, requirement items can increase the extension and
adjustment capability of requirements change.
• Based on modularity inspection, in requirements change, affected requirement items and
documents can be timely isolated.
(3) Manageable, controllable and traceable development documents:
• Based on CM procedure, the development documents and user stories can be identified and
managed.
• Based on version control and tools, the development documents and user stories versions
difference and revision contents can be preserved and controlled.
• Based on change control procedure, the change requests can careful control and
management to reduce change risk of software development.

39
Figure 5. Flowchart of Agile Development Maintainability Enhancement (ADME) Procedure
6. CONCLUSIONS
Success software project must conquer requirements change challenges. Any requirements
change always affects to software development operations and add software development failure
ratio. Requirements change needs invest extra resource and cost, and cause project delay.
Accepted requirements change, the affected development documents and tasks can’t be
effectively isolated will increase software development risk. Agile development applies IID
model and very cares about the communication, working software, and refactoring features. IID
and refactoring can reduce partial risk of requirements change. However, agile development
existed some maintenance quality defects that include development documents quality, user story
inspection mechanism and CM system. Agile development should enhance maintenance quality
to reduce requirements change risk. For improving the maintenance quality of agile development,
the paper proposes the Agile Development Maintainability Measurement (ADMM) model. Based
on ADMM model, the Agile Development Maintainability Enhancement (ADME) procedure is
defined and deployed for reducing the risk of requirements change. Agile development
methodology enhancement maintainability can easy handle requirements change to reduce

40
software development risk. The advantages of ADMM model and ADME procedure are
described as follows:
(1) Concretely identify agile development maintenance quality defects and provide correction
suggestions.
(2) Effectively improve agile development maintenance quality can concretely handle
requirements change and reducing development risk.
(3) Combination formulas of ADMM model have precise, simple and flexible adjustment
features. Based on user or product features, development team can easy adjust or modify the
weights of combination formulas.
(4) Combined with ADME model, ADME procedure has continuous improvement capability on
the changeable applications environment, and keep up with the times.
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AUTHOR
Sen-Tarng Lai was born in Taiwan in 1959. He received his BS from Soochow University, Taiwan in 1982,
master from National Chiao Tung University, Taiwan in 1984 and PhD from National Taiwan University of
Science and Technology, Taiwan in 1997. His research interests include software security, software project
management, and software quality. He is currently an assistant professor in the Department of Information
Technology and Management at Shin Chien University, Taipei, Taiwan.

A maintainability enhancement procedure

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