The software requirements are description of features and functionalities of the target system. Requirements convey the expectations of users from the software product. The requirements can be obvious or hidden, known or unknown, expected or unexpected from client’s point of view.
The process to gather the software requirements from client, analyze and document them is known as requirement engineering.
The goal of requirement engineering is to develop and maintain sophisticated and descriptive ‘System Requirements Specification’ document.
Requirement Engineering Process
It is a four step process, which includes –
Software Requirement Specification
Software Requirement Validation
Let us see the process briefly -
When the client approaches the organization for getting the desired product developed, it comes up with rough idea about what all functions the software must perform and which all features are expected from the software.
Referencing to this information, the analysts does a detailed study about whether the desired system and its functionality are feasible to develop.
This feasibility study is focused towards goal of the organization. This study analyzes whether the software product can be practically materialized in terms of implementation, contribution of project to organization, cost constraints and as per values and objectives of the organization. It explores technical aspects of the project and product such as usability, maintainability, productivity and integration ability.
The output of this phase should be a feasibility study report that should contain adequate comments and recommendations for management about whether or not the project should be undertaken.
If the feasibility report is positive towards undertaking the project, next phase starts with gathering requirements from the user. Analysts and engineers communicate with the client and end-users to know their ideas on what the software should provide and which features they want the software to include.
Software Requirement Specification
SRS is a document created by system analyst after the requirements are collected from various stakeholders.
SRS defines how the intended software will interact with hardware, external interfaces, speed of operation, response time of system, portability of software across various platforms, maintainability, speed of recovery after crashing, Security, Quality, Limitations etc.
The requirements received from client are written in natural language. It is the responsibility of system analyst to document the requirements in technical language so that they can be comprehended and useful by the software development team.
SRS should come up with following features:
User Requirements are expressed in natural language.
Technical requirements are expressed in structured language, which is used inside the organization.
Design description should be written in Pseudo code.
Format of Forms and GUI screen prints.
Conditional and mathematical notations for DFDs etc.
Software Requirement Validation
After requirement specifications are developed, the requirements mentioned in this document are validated. User might ask for illegal, impractical solution or experts may interpret the requirements incorrectly. This results in huge increase in cost if not nipped in the bud. Requirements can be checked against following conditions -
If they can be practically implemented
If they are valid and as per functionality and domain of software
If there are any ambiguities
If they are complete
If they can be demonstrated
Requirement Elicitation Process
Requirement elicitation process can be depicted using the folloiwng diagram:
Requirements gathering - The developers discuss with the client and end users and know their expectations from the software.
Organizing Requirements - The developers prioritize and arrange the requirements in order of importance, urgency and convenience.
Negotiation & discussion - If requirements are ambiguous or there are some conflicts in requirements of various stakeholders, if they are, it is then negotiated and discussed with stakeholders. Requirements may then be prioritized and reasonably compromised.
The requirements come from various stakeholders. To remove the ambiguity and conflicts, they are discussed for clarity and correctness. Unrealistic requirements are compromised reasonably.
Documentation - All formal & informal, functional and non-functional requirements are documented and made available for next phase processing.
Requirement Elicitation Techniques
Requirements Elicitation is the process to find out the requirements for an intended software system by communicating with client, end users, system users and others who have a stake in the software system development.
There are various ways to discover requirements
Interviews are strong medium to collect requirements. Organization may conduct several types of interviews such as:
Structured (closed) interviews, where every single information to gather is decided in advance, they follow pattern and matter of discussion firmly.
Non-structured (open) interviews, where information to gather is not decided in advance, more flexible and less biased.
One-to-one interviews which are held between two persons across the table.
Group interviews which are held between groups of participants. They help to uncover any missing requirement as numerous people are involved.
Organization may conduct surveys among various stakeholders by querying about their expectation and requirements from the upcoming system.
A document with pre-defined set of objective questions and respective options is handed over to all stakeholders to answer, which are collected and compiled.
A shortcoming of this technique is, if an option for some issue is not mentioned in the questionnaire, the issue might be left unattended.
Team of engineers and developers may analyze the operation for which the new system is required. If the client already has some software to perform certain operation, it is studied and requirements of proposed system are collected.
Every software falls into some domain category. The expert people in the domain can be a great help to analyze general and specific requirements.
An informal debate is held among various stakeholders and all their inputs are recorded for further requirements analysis.
Prototyping is building user interface without adding detail functionality for user to interpret the features of intended software product. It helps giving better idea of requirements. If there is no software installed at client’s end for developer’s reference and the client is not aware of its own requirements, the developer creates a prototype based on initially mentioned requirements. The prototype is shown to the client and the feedback is noted. The client feedback serves as an input for requirement gathering.
Team of experts visit the client’s organization or workplace. They observe the actual working of the existing installed systems. They observe the workflow at client’s end and how execution problems are dealt. The team itself draws some conclusions which aid to form requirements expected from the software.
Software Requirements Characteristics
Gathering software requirements is the foundation of the entire software development project. Hence they must be clear, correct and well-defined.
A complete Software Requirement Specifications must be:
We should try to understand what sort of requirements may arise in the requirement elicitation phase and what kinds of requirements are expected from the software system.
Broadly software requirements should be categorized in two categories:
Requirements, which are related to functional aspect of software fall into this category.
They define functions and functionality within and from the software system.
Search option given to user to search from various invoices.
User should be able to mail any report to management.
Users can be divided into groups and groups can be given separate rights.
Should comply business rules and administrative functions.
Software is developed keeping downward compatibility intact.
Requirements, which are not related to functional aspect of software, fall into this category. They are implicit or expected characteristics of software, which users make assumption of.
Non-functional requirements include -
Requirements are categorized logically as
Must Have : Software cannot be said operational without them.
Should have : Enhancing the functionality of software.
Could have : Software can still properly function with these requirements.
Wish list : These requirements do not map to any objectives of software.
While developing software, ‘Must have’ must be implemented, ‘Should have’ is a matter of debate with stakeholders and negation, whereas ‘could have’ and ‘wish list’ can be kept for software updates.
User Interface requirements
UI is an important part of any software or hardware or hybrid system. A software is widely accepted if it is -
easy to operate
quick in response
effectively handling operational errors
providing simple yet consistent user interface
User acceptance majorly depends upon how user can use the software. UI is the only way for users to perceive the system. A well performing software system must also be equipped with attractive, clear, consistent and responsive user interface. Otherwise the functionalities of software system can not be used in convenient way. A system is said be good if it provides means to use it efficiently. User interface requirements are briefly mentioned below -
Consistent UI elements
Strategical use of color and texture.
Provide help information
User centric approach
Group based view settings.
Software System Analyst
System analyst in an IT organization is a person, who analyzes the requirement of proposed system and ensures that requirements are conceived and documented properly & correctly. Role of an analyst starts during Software Analysis Phase of SDLC. It is the responsibility of analyst to make sure that the developed software meets the requirements of the client.
System Analysts have the following responsibilities:
Analyzing and understanding requirements of intended software
Understanding how the project will contribute in the organization objectives
Identify sources of requirement
Validation of requirement
Develop and implement requirement management plan
Documentation of business, technical, process and product requirements
Coordination with clients to prioritize requirements and remove and ambiguity
Finalizing acceptance criteria with client and other stakeholders
Software Metrics and Measures
Software Measures can be understood as a process of quantifying and symbolizing various attributes and aspects of software.
Software Metrics provide measures for various aspects of software process and software product.
Software measures are fundamental requirement of software engineering. They not only help to control the software development process but also aid to keep quality of ultimate product excellent.
According to Tom DeMarco, a (Software Engineer), “You cannot control what you cannot measure.” By his saying, it is very clear how important software measures are.
Let us see some software metrics:
Size Metrics - LOC (Lines of Code), mostly calculated in thousands of delivered source code lines, denoted as KLOC.
Function Point Count is measure of the functionality provided by the software. Function Point count defines the size of functional aspect of software.
Complexity Metrics - McCabe’s Cyclomatic complexity quantifies the upper bound of the number of independent paths in a program, which is perceived as complexity of the program or its modules. It is represented in terms of graph theory concepts by using control flow graph.
Quality Metrics - Defects, their types and causes, consequence, intensity of severity and their implications define the quality of product.
The number of defects found in development process and number of defects reported by the client after the product is installed or delivered at client-end, define quality of product.
Process Metrics - In various phases of SDLC, the methods and tools used, the company standards and the performance of development are software process metrics.
Resource Metrics - Effort, time and various resources used, represents metrics for resource measurement.
A Software Project is the complete procedure of software development from requirement gathering to testing and maintenance, carried out according to the execution methodologies, in a specified period of time to achieve intended software product.
Need of software project management
Software is said to be an intangible product. Software development is a kind of all new stream in world business and there’s very little experience in building software products. Most software products are tailor made to fit client’s requirements. The most important is that the underlying technology changes and advances so frequently and rapidly that experience of one product may not be applied to the other one. All such business and environmental constraints bring risk in software development hence it is essential to manage software projects efficiently.
The image above shows triple constraints for software projects. It is an essential part of software organization to deliver quality product, keeping the cost within client’s budget constrain and deliver the project as per scheduled. There are several factors, both internal and external, which may impact this triple constrain triangle. Any of three factor can severely impact the other two.
Therefore, software project management is essential to incorporate user requirements along with budget and time constraints.
Software Project Manager
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.
A project manager closely monitors the development process, prepares and executes various plans, arranges necessary and adequate resources, maintains communication among all team members in order to address issues of cost, budget, resources, time, quality and customer satisfaction.
Let us see few responsibilities that a project manager shoulders -
Act as project leader
Liaison with stakeholders
Managing human resources
Setting up reporting hierarchy etc.
Defining and setting up project scope
Managing project management activities
Monitoring progress and performance
Risk analysis at every phase
Take necessary step to avoid or come out of problems
Act as project spokesperson
Software Management Activities
Software project management comprises of a number of activities, which contains planning of project, deciding scope of software product, estimation of cost in various terms, scheduling of tasks and events, and resource management. Project management activities may include:
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:
It defines the scope of project; this includes all the activities, process need to be done in order to make a deliverable software product. Scope management is essential because it creates boundaries of the project by clearly defining what would be done in the project and what would not be done. This makes project to contain limited and quantifiable tasks, which can easily be documented and in turn avoids cost and time overrun.
During Project Scope management, it is necessary to -
Define the scope
Decide its verification and control
Divide the project into various smaller parts for ease of management.
Verify the scope
Control the scope by incorporating changes to the scope
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 estimation
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 -
Size of software
Additional software or tools, licenses etc.
Skilled personnel with task-specific skills
Training and support
Project Estimation Techniques
We discussed various parameters involving project estimation such as size, effort, time and cost.
Project manager can estimate the listed factors using two broadly recognized techniques –
This technique assumes the software as a product of various compositions.
There are two main models -
Line of Code Estimation is done on behalf of number of line of codes in the software product.
Function Points Estimation is done on behalf of number of function points in the software product.
Empirical Estimation Technique
This technique uses empirically derived formulae to make estimation.These formulae are based on LOC or FPs.
This model is made by Lawrence H. Putnam, which is based on Norden’s frequency distribution (Rayleigh curve). Putnam model maps time and efforts required with software size.
COCOMO stands for COnstructive COst MOdel, developed by Barry W. Boehm. It divides the software product into three categories of software: organic, semi-detached and embedded.
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 them 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 -
Break down the project tasks into smaller, manageable form
Find out various tasks and correlate them
Estimate time frame required for each task
Divide time into work-units
Assign adequate number of work-units for each task
Calculate total time required for the project from start to finish
All elements used to develop a software product may be assumed as resource for that project. This may include human resource, productive tools and software libraries.
The resources are available in limited quantity and stay in the organization as a pool of assets. The shortage of resources hampers the development of project and it can lag behind the schedule. Allocating extra resources increases development cost in the end. It is therefore necessary to estimate and allocate adequate resources for the project.
Resource management includes -
Defining proper organization project by creating a project team and allocating responsibilities to each team member
Determining resources required at a particular stage and their availability
Manage Resources by generating resource request when they are required and de-allocating them when they are no more needed.
Project Risk Management
Risk management involves all activities pertaining to identification, analyzing and making provision for predictable and non-predictable risks in the project. Risk may include the following:
Experienced staff leaving the project and new staff coming in.
Change in organizational management.
Requirement change or misinterpreting requirement.
Under-estimation of required time and resources.
Technological changes, environmental changes, business competition.
Risk Management Process
There are following activities involved in risk management process:
Identification - Make note of all possible risks, which may occur in the project.
Categorize - Categorize known risks into high, medium and low risk intensity as per their possible impact on the project.
Manage - Analyze the probability of occurrence of risks at various phases. Make plan to avoid or face risks. Attempt to minimize their side-effects.
Monitor - Closely monitor the potential risks and their early symptoms. Also monitor the effects of steps taken to mitigate or avoid them.