UNIT 4
Software Project Management
Software project management is an art and discipline of planning and supervising software projects. It is a sub-discipline of software project management in which software projects planned, implemented, monitored and controlled.
A software project manager is a person who undertakes the responsibility of executing the software project. Software project manager is thoroughly aware of all the phases of SDLC that the software would go through. Project manager may never directly involve in producing the end product but he controls and manages the activities involved in production.
Figure: 1 Project planning activities
Software Measurement and Metrics
Software measurement is a method to measure software characteristics which are measurable or countable with the help of metrics. Software metrics are used to measure software performance, planning work items, measuring productivity, and many other uses. Software metrics are similar to the four functions of management: Planning, Organization, Control, or Improvement.
To measures of various characteristics of the software, product metrics are used: on the basis of -
These metrics can be computed for different stages of SDLC.
b. Process Metrics:
To measures various characteristics of the software development process. For example, the efficiency of fault detection etc..
Responsibilities of project manager shoulders -
Managing People
Managing Project
Software measurement life cycle
Many other metrics include the following:
LOC Metrics- It is simplest size based metrics for calculating size of program. It is computed by normalizing the quality and productivity measures by considering the size of the product as a metric.
In size-oriented metrics:
b. Halstead's software science
In Halstead's "A code is an implementation of an algorithm considered to be a collection of tokens which can be classified as either operators or operand."
Token Count- All program metrics can be defined in basic symbols. These symbols are called as a token.
n1 = count of unique operators, n2 = count of unique operands.
N1 = count of total occurrences of operators. N2 = count of total occurrence of operands, size of the program can be expressed as N = N1 + N2.
Halstead metrics :
Program Volume (V)- The unit of measurement of volume is the standard unit for size "bits."
V=N*log2n
Program Level (L)- The value of L ranges between zero and one, with L=1 representing a program written at the highest possible level (i.e., with minimum size).
L=V*/V
Program Difficulty-The difficulty level or error-proneness (D) of the program is proportional to the number of the unique operator in the program.
D= (n1/2) * (N2/n2)
Programming Effort (E)- The unit of measurement of E is elementary mental discriminations.
E=V/L=D*V
Estimated Program Length-it is the length of a well-structured program is a function only of the number of unique operators and operands.
N=N1+N2
And estimated program length is denoted by N^
N^ = n1log2n1 + n2log2n2
The following alternate expressions have been published to estimate program length:
NJ = log2 (n1!) + log2 (n2!)
NB = n1 * log2n2 + n2 * log2n1
NC = n1 * sqrt(n1) + n2 * sqrt(n2)
NS = (n * log2n) / 2
Potential Minimum Volume- V* is defined as the volume of the most short program in which a problem can be coded.
V* = (2 + n2*) * log2 (2 + n2*), Here, n2* is the count of unique input and output parameters
Size of Vocabulary (n)-The size of the vocabulary of a program, which consists of the number of unique tokens used to build a program, is defined as:
n=n1+n2 where n=vocabulary of a program
n1=number of unique operators
n2=number of unique operands
Language Level – calculates algorithm implementation program language level. The same algorithm take extra effort if it is written in a low-level program language. Hence, it is easier to program in Pascal than in Assembler.
L' = V / D / D
lambda = L * V* = L2 * V
For an effective management accurate estimation of various measures is a must. With correct estimation managers can manage and control the project more efficiently and effectively.
Project estimation may involve the following:
Software size may be estimated either in terms of KLOC (Kilo Line of Code) or by calculating number of function points in the software. Lines of code depend upon coding practices and Function points vary according to the user or software requirement.
The managers estimate efforts in terms of personnel requirement and man-hour required to produce the software. For effort estimation software size should be known. This can either be derived by managers’ experience, organization’s historical data or software size can be converted into efforts by using some standard formulae.
Once size and efforts are estimated, the time required to produce the software can be estimated. Efforts required is segregated into sub categories as per the requirement specifications and interdependency of various components of software. Software tasks are divided into smaller tasks, activities or events by Work Breakthrough Structure (WBS). The tasks are scheduled on day-to-day basis or in calendar months.
The sum of time required to complete all tasks in hours or days is the total time invested to complete the project.
This might be considered as the most difficult of all because it depends on more elements than any of the previous ones. For estimating project cost, it is required to consider -
Estimation is done on behalf of number of line of codes in the software product.
b. Function Point (FP) based measures
Estimation is done on behalf of number of function points in the software product.
Code documentation
The coding is the process of converting the design specifications of a project into the source code of programming language. It is necessary to write source code & internal documentation so that conformance of the code to its specification can be easily verified.
Coding is a process which can reduce cost testing and maintenance done by programmers.
Coding standards and guidelines are summarized in figures below:
Points to keep in mind while coding :
a) Clarity and simplicity of Expression.
b) Naming
c) Control Constructs
d) Information hiding
e) Nesting
f) User-defined types
g) Module size
h) Module Interface
i) Side-effects
Project Planning
Software project planning is task, which is performed before the production of software actually starts. It is there for the software production but involves no concrete activity that has any direction connection with software production; rather it is a set of multiple processes, which facilitates software production. Project planning may include the following:
c. Various Size Oriented Measures
LOC Metrics- It is simplest size based metrics for calculating size of program. It is computed by normalizing the quality and productivity measures by considering the size of the product as a metric.
In size-oriented metrics:
d. Halstead's software science
In Halstead's "A code is an implementation of an algorithm considered to be a collection of tokens which can be classified as either operators or operand."
Token Count- All program metrics can be defined in basic symbols. These symbols are called as a token.
n1 = count of unique operators, n2 = count of unique operands.
N1 = count of total occurrences of operators. N2 = count of total occurrence of operands, size of the program can be expressed as N = N1 + N2.
Halstead metrics :
Program Volume (V)- The unit of measurement of volume is the standard unit for size "bits."
V=N*log2n
Program Level (L)- The value of L ranges between zero and one, with L=1 representing a program written at the highest possible level (i.e., with minimum size).
L=V*/V
Program Difficulty-The difficulty level or error-proneness (D) of the program is proportional to the number of the unique operator in the program.
D= (n1/2) * (N2/n2)
Programming Effort (E)- The unit of measurement of E is elementary mental discriminations.
E=V/L=D*V
Estimated Program Length-it is the length of a well-structured program is a function only of the number of unique operators and operands.
N=N1+N2
And estimated program length is denoted by N^
N^ = n1log2n1 + n2log2n2
The following alternate expressions have been published to estimate program length:
NJ = log2 (n1!) + log2 (n2!)
NB = n1 * log2n2 + n2 * log2n1
NC = n1 * sqrt(n1) + n2 * sqrt(n2)
NS = (n * log2n) / 2
Potential Minimum Volume- V* is defined as the volume of the most short program in which a problem can be coded.
V* = (2 + n2*) * log2 (2 + n2*), Here, n2* is the count of unique input and output parameters
Size of Vocabulary (n)-The size of the vocabulary of a program, which consists of the number of unique tokens used to build a program, is defined as:
n=n1+n2 where n=vocabulary of a program
n1=number of unique operators
n2=number of unique operands
Language Level – calculates algorithm implementation program language level. The same algorithm take extra effort if it is written in a low-level program language. Hence, it is easier to program in Pascal than in Assembler.
L' = V / D / D
lambda = L * V* = L2 * V
For an effective management accurate estimation of various measures is a must. With correct estimation managers can manage and control the project more efficiently and effectively.
Project estimation may involve the following:
Software size may be estimated either in terms of KLOC (Kilo Line of Code) or by calculating number of function points in the software. Lines of code depend upon coding practices and Function points vary according to the user or software requirement.
The managers estimate efforts in terms of personnel requirement and man-hour required to produce the software. For effort estimation software size should be known. This can either be derived by managers’ experience, organization’s historical data or software size can be converted into efforts by using some standard formulae.
Once size and efforts are estimated, the time required to produce the software can be estimated. Efforts required is segregated into sub categories as per the requirement specifications and interdependency of various components of software. Software tasks are divided into smaller tasks, activities or events by Work Breakthrough Structure (WBS). The tasks are scheduled on day-to-day basis or in calendar months.
The sum of time required to complete all tasks in hours or days is the total time invested to complete the project.
This might be considered as the most difficult of all because it depends on more elements than any of the previous ones. For estimating project cost, it is required to consider -
Project Size estimation Metrics
c. Line of Code (LOC)
Estimation is done on behalf of number of line of codes in the software product.
d. Function Point (FP) based measures
Estimation is done on behalf of number of function points in the software product.
In the early 80’s, Barry Boehm developed a model called COCOMO (COnstructive COstMOdel) to estimate total effort required to develop the software project. COCOMO model is commonly used as it is based on the study of already developed software projects. While estimating total effort for a software project, cost of development, management, and other support tasks are included. However, cost of secretarial and other staff are excluded.
In this model, size is measured in terms of thousands of delivered lines of code (KDLOC). In order to estimate effort accurately, COCOMO model divides projects into three categories listed below:
Organic projects: These projects are small in size (not more than 50 KDLOC) and thus easy to develop. In organic projects, small teams with prior experience work together to accomplish user requirements, which are less demanding. Most people involved in these projects have thorough understanding of how the software under development contributes in achieving the organization objectives. Examples of organic projects include simple business system, inventory management system, payroll management system, and library management system.
Embedded projects: These projects are complex in nature (size is more than 300KDLOC) and the organizations have less experience in developing such type of projects. Developers also have to meet stringent user requirements. These software projects are developed under constraints (hardware, software, and people).
Examples of embedded systems include software system used in avionics and military hardware.
• Semi-detached projects: These projects are less complex as the user requirements are less stringent compared to embedded projects. The size of semi-detached project is not more than 300 KDLOC. Examples of semi-detached projects include operating system, compiler design, and database design
Types of Models:
Basic COCOMO can be used for quick and slightly rough calculations of Software Costs. Its accuracy is not very reliable.
Effort=a1*(KLOC) a2 PM
Tdev=b1*(efforts)b2 Months
Where KLOC is the estimated size of the software product indicate in Kilo Lines of Code,
a1,a2,b1, b2 are constants for each group of software products,
Tdev is the estimated time to develop the software, expressed in months,
Effort is the total effort required to develop the software product, expressed in person months (PMs).
Intermediate COCOMO takes Cost Drivers into account
Intermediate COCOMO equation:
E=ai (KLOC) bi*EAF
D=ci (E)di
EAF = Effort adjustment factor
A table for Coefficients for intermediate COCOMO is given below:
Detailed COCOMO additionally accounts for the influence of individual project phases, i.e in case of Detailed it accounts for both these cost drivers and also calculations are performed phase wise henceforth producing a more accurate result. The Six phases of detailed COCOMO are:
Planning and requirements
System structure
Complete structure
Module code and test
Integration and test
Cost Constructive model
Project manager has to determine the actual Staff Estimation number after the effort required to develop a software is known.
Norden Estimation: Norden studied the Staffing patterns of R & D projects and proposed. Staffing level patterns can be approximated by "Rayleigh Distribution Curve" which specifies that the relationship between applied effort and delivery time for software project. It is also called Putnam- NORDEN-Rayleigh Curve or PNR curve.
In 1976, Putnam studied the problem of staffing of software projects observed that the level of effort required in software development efforts has a similar envelope.Putnam analysed a large number of projects, and gave the expression:
L=CkK1/3td4/3
K is the effort expended and L is the size in KLOC.
td is the time to develop the software.
Ck is the state of technology constant reflects factors that affect programmer productivity.
Project Scheduling in a project refers to roadmap of all activities to be done with specified order and within time slot allotted to each activity. Project managers tend to define various tasks, and project milestones and arrange them keeping various factors in mind. They look for tasks lie in critical path in the schedule, which are necessary to complete in specific manner (because of task interdependency) and strictly within the time allocated. Arrangement of tasks which lies out of critical path are less likely to impact over all schedule of the project.
For scheduling a project, it is necessary to -
Risk management involves all activities pertaining to identification, analysing and making provision for predictable and non-predictable risks in the project. Risk may include the following:
Figure: 2 Risk Management Activities
Risk Management Process
There are following activities involved in risk management process:
