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(A) System Requirement Specifications(SRS) Documentation/Document
Introduction
- A well-structured and comprehensive System Requirements Specification (SRS) document is crucial for successfully developing a software system.
Definition
- System requirement specification is a set of complete and precisely stated properties along with the constraints of the system that the software must satisfy.
- A System Requirements Specification (SRS) document is a comprehensive description of the intended purpose, functionality, and constraints of a software system. It details what the system should do, how it should perform, and under what conditions it must operate.
- The SRS serves as a blueprint for developers/the development team, project managers, and stakeholders, ensuring that everyone involved has a clear understanding of the system’s requirements and expectations. It provides a clear and detailed blueprint for the entire development process, ensuring that all stakeholders have a shared understanding of what the system will do, what the software should do, how it should behave, how it will perform, and the conditions under which it must operate.
- SRS lays out the functional and non-functional requirements, design constraints, and other key elements necessary for the system’s development.
- SRS documents the system with high-level requirements without going into details of implementation issues.
- SRS defines the priority of each requirement to guide the development process and ensure that the most critical features are implemented first.
Characteristics of SRS
- All the requirements must be stated unambiguously. Every requirement stated has only one interpretation. Every characteristic of the final product must be described using a single and unique term.
- It should be complete. The definition should include all functions and constraints intended by the system user. In addition to the requirements of the system, as specified by the user, it must conform to any standard that applies to it.
- The requirements should be realistic and achievable with current technology. There is no point in specifying requirements that are unrealizable using existing hardware and software technology.
- It must be verifiable and consistent. The requirements should be shown to be consistent and verifiable. The requirements are verified by the system tester during system testing. No requirement should conflict with any other requirement.
- It should be modifiable i.e., the structure and style of the SRS are such that any necessary changes to the requirements can be made easily, completely, and consistently.
- It should be traceable to other requirements and related documents. The origin of each requirement must be clear.
- The SRS should facilitate the referencing of each requirement for future development or enhancement of documentation. Each requirement must refer to its source in previous documents.
- SRS should not only address the explicit requirements but also implicit requirements that may come up during the maintenance phase of the software. It must be usable during the operation and maintenance phase. The SRS must address the needs of the operation and maintenance phase, including the eventual replacement of the software.
Requirements/Importance/Purpose of an SRS Document
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The SRS should specify only the external system behavior and not the internal details.
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A well-designed software requirements specification establishes boundaries and solutions for a system to develop useful software.
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- SRS also specifies any constraints imposed on implementation.
- SRS serves as the foundation for the development of a system and the basis for system design, development, and testing.
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A good SRS is flexible to change and acts as a reference tool for system developers, administrators, and maintainers.
- SRS defines the boundaries of the system’s functionality, helping to manage scope and avoid feature creep.
- SRS acts as a formal agreement between the client and developers regarding what the system will do.
- By using best practices in creating and maintaining the SRS, organizations can reduce the risk of misunderstandings, scope creep, and project delays, leading to a more efficient and successful development process.
Criteria/Rules for Creating an SRS Document
- For successful software development, SRS should involve all the relevant Stakeholders in the requirements-gathering process to capture a complete and accurate set of requirements.
- A good SRS uses clear, unambiguous language to describe the requirements, avoiding vague or general statements.
- An industry standard should be applied and used to ensure that standard formats are used to describe the requirements.
- Completeness and consistency between various documents must be ensured.
- Use standard models to specify functional relationships, data flow between the systems and sub-systems, and data structure to express complete requirements.
- Limit the structure of paragraphs to a list of individual sentences to increase the tractability and modifiability of each requirement and to increase the ability to check for completeness. It helps in modifying the document when required.
- Phrase each sentence into a simple sentence. This is to increase the verifiability of each requirement stated in the document.
- SRS should include related and proper diagrams, flowcharts, or models to illustrate complex requirements and relationships between components.
- An SRS validates the requirements by reviewing the SRS document with stakeholders to ensure that the requirements are accurate, complete, and feasible.
- Regularly update the SRS document to reflect changes in requirements or scope as the project progresses.
Structural of an SRS Document
A typical SRS document contains the following
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Introduction: It includes
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- Purpose: This explains the purpose of the SRS document, including what it aims to achieve.
- Scope: It defines the system’s boundaries, describing what it will and will not do.
- Definitions, Acronyms, and Abbreviations: It provides definitions for any specialized terms, acronyms, or abbreviations used in the document.
- Goals and Objectives: It defines the document’s business objectives and the software’s goals and objectives, describing it in the context of the computer-based system.
- References: This lists any documents, standards, or resources referenced in the SRS.
- Overview: This summarizes the contents of the SRS document, providing a high-level overview of what is included.
- Overall Informative System Description: It includes
- System Perspective: It describes how the system fits into the overall business or technical environment, including its interfaces with other systems or processes.
- System Structure: It includes Information content and structure representation along with a description of sub-systems and System interface.
- Problem Details: It includes a detailed description of the problems that the software must solve by knowing the details of Information flow, content, and structure are documented.
- System Functions: It provides a high-level description of the main functions the system will perform. It represents information flow representation.
- User Types: It identifies the different types of users who will interact with the system and describes their characteristics, such as experience level or specific needs.
- Operating Environment: This gives the details of the environment in which the system will operate, including hardware, software, network infrastructure, and any other relevant conditions.
- Design and Implementation Constraints: This includes the list of any constraints that will affect the system’s design or implementation, such as regulatory requirements, technology limitations, or budgetary restrictions.
- Assumptions and Dependencies: It outlines any assumptions made during the creation of the SRS and any dependencies on external factors or systems.
- System Features: It includes
- Feature Description: It provides a detailed description of each major system feature or functionality. Each feature should be described in terms of its inputs, processing, and outputs.
- Priority: It indicates the priority of each feature, helping to determine the order of implementation.
- Use Cases: It describes scenarios or use cases that illustrate how the feature will be used.
- Functional Requirements: It specifies the specific requirements associated with the feature, including the conditions under which it will operate and the expected outcomes.
- Constraints: It lists any constraints that apply to the feature, such as performance limits, security requirements, or interface dependencies.
- External Interface Requirements: It includes
- User Interfaces: This describes the requirements for the system’s user interfaces, including screen layouts, input methods, and interaction styles.
- Hardware Interfaces: This details the hardware components that the system will interact with, including communication protocols, data formats, and physical connections.
- Software Interfaces: This outlines the software interfaces, such as APIs, data exchange formats, and communication protocols with other software systems.
- Communication Interfaces: It specifies the requirements for communication between the system and external systems, networks, or devices, including protocols, bandwidth, and data transmission methods.
- Functional Description of the system: It includes
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Functional description.
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Restrictions/limitations.
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Performance requirements.
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Design constraints.
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Diagrams to represent the overall structure of the software graphically.
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- System Details: It includes
- Performance Requirements: It defines the system’s performance criteria, such as response times, throughput, and resource usage.
- Security Requirements: It specifies the security measures that must be implemented to protect the system and its data, including authentication, authorization, encryption, and data integrity.
- Reliability: It describes the system’s reliability requirements, such as uptime, failure rates, and recovery procedures.
- Availability: It specifies the required availability of the system, including acceptable downtime and maintenance windows.
- Scalability: It outlines the system’s ability to scale to accommodate growth in users, transactions, or data.
- Maintainability: It defines the requirements for maintaining and updating the system, including ease of maintenance, tools, and documentation.
- Portability: It describes the system’s ability to be transferred to different environments, such as different hardware platforms or operating systems.
- Usability: It specifies the usability requirements, including ease of use, accessibility, and user satisfaction criteria.
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Other Non-Functional Requirements: It includes
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Compliance Requirements: It gives the details of any legal, regulatory, or standards compliance that the system must adhere to.
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Safety Requirements: It outlines any safety-related requirements that are critical for the system’s operation, especially in environments where safety is a concern.
- Cultural and Political Requirements: It describes any cultural or political considerations that may impact the system’s design or operation, such as language support or region-specific regulations.
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- Test and validation criteria: It includes
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Performance limitation, if any.
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Expected software response.
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Time and attention must be given to this section.
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Appendix: It includes supplementary information to the specification.
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Glossary: It provides a glossary of terms used in the document, helping to clarify any specialized language. It defines all technical or software-specific terms used in the document.
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Bibliography/References: It lists any additional documents, standards, or resources that are relevant to the SRS. It lists and references all documents(books, site links, etc) that relate to the software.
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Change History: It includes a log of changes made to the document, including the date, author, and description of the changes.
(B) Analysis Documentation/Document
- An Analysis Document is a crucial part of the software development process, typically created during the analysis phase.
- The Analysis Document is essential in ensuring that all requirements are thoroughly understood and documented before moving into the design and development phases.
- It provides a solid foundation for building a system that meets the stakeholders’ needs and aligns with business objectives.
- It is designed to capture, analyze, and document the detailed requirements of a software system and lay the groundwork for the design and development phases.
- This document serves as a bridge between the initial requirement gathering and the technical design of the system.
- This document specifies the functional and non-functional requirements that the system must fulfill.
- This document provides a solid foundation for the system’s architecture and design phases, ensuring that all requirements are considered.
Components/Steps of Analysis Documentation
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Introduction: It includes –
- Purpose: It describes the purpose of the analysis document and its intended audience.
- Scope: It defines the boundaries of the system being analyzed, including what is and isn’t covered.
- Definitions, Acronyms, and Abbreviations: It explains any specific terms used within the document.
- References: It lists any reference materials, previous documents, or other sources used during the analysis.
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System Overview: It includes –
- System Context: This describes the system’s context within the business or environment, including how it interacts with other systems or processes.
- Business Objectives: This explains the business goals the system is intended to achieve.
- Stakeholders: This identifies the key stakeholders involved, including their roles and interests in the system.
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Current System (if applicable): It includes –
- Overview of the Existing System: This provides a summary of the current system or process in place.
- Problems and Limitations: This gives the details of the issues, inefficiencies, or limitations of the current system that the new system aims to address.
- Data Flow: It illustrates how data moves through the current system, highlighting bottlenecks or pain points.
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Requirements Analysis: It includes –
- Functional Requirements: This is a detailed breakdown of the functionalities the new system must provide. Each functional requirement typically includes:
- Description: A clear description of the requirement.
- Priority: The importance of the requirement.
- Inputs and Outputs: The data involved in each function.
- Process Description: How the system will handle the input to produce the required output.
- Non-Functional Requirements: It includes requirements that define the system’s quality attributes, such as:
- Performance: Speed, scalability, and responsiveness.
- Security: Data protection, user authentication, and access control.
- Usability: Ease of use and user interface considerations.
- Reliability: System stability and fault tolerance.
- Maintainability: How easy it is to update or modify the system.
- Compatibility: Integration with other systems and software.
- Use Cases: It includes detailed scenarios that describe how different users (actors) will interact with the system. Each use case typically includes:
- Actors: Identifies the users or external systems that interact with the system.
- Preconditions: Conditions that must be met before the use case starts.
- Main Flow: The primary sequence of steps taken during the use case.
- Alternate Flows: Any deviations or exceptions from the main flow.
- Postconditions: The state of the system after the use case is completed.
- Functional Requirements: This is a detailed breakdown of the functionalities the new system must provide. Each functional requirement typically includes:
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Data Analysis: It includes –
- Data Entities: It defines the key data entities the system will manage.
- Entity-Relationship Diagrams (ERD): This is the visual representation of the relationships between different data entities.
- Data Dictionary: This is a detailed description of each data element, including its format, type, and constraints.
- Data Flow Diagrams (DFD): It depict how data moves through the system, including data sources, processes, and destinations.
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Process Analysis: It includes –
- Business Processes: It describes the key business processes that the system will support or automate.
- Process Flow Diagrams: It is the visual representations of the processes, showing the flow of tasks and decision points.
- Workflow Descriptions: This includes detailed descriptions of how work is carried out within the system.
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System Models: It includes –
- Logical Data Model: It gives the abstract representation of the data structures and relationships in the system.
- Behavioral Models: It includes state diagrams, sequence diagrams, and activity diagrams to represent the dynamic behavior of the system.
- Class Diagrams: It depicts the system’s object-oriented structure, including classes, attributes, methods, and relationships.
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Constraints and Assumptions: It includes –
- Technical Constraints: These may include any limitations imposed by hardware, software, or other technology.
- Business Constraints: These may include constraints related to budgets, timelines, or business policies.
- Assumptions: It focuses on any assumptions made during the analysis that could impact the system’s design or implementation.
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Risk Analysis: It includes –
- Identified Risks: It identifies potential risks associated with the system development, including technical, operational, and business risks.
- Risk Mitigation Strategies: It proposes strategies for reducing or managing these risks.
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Conclusion: It includes –
- Summary: It uses a brief recap of the key findings and decisions made during the analysis phase.
- Next Steps: It outlines the next steps in the project, typically moving toward the system design phase.
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Appendices: It includes –
- Glossary: It gives the definitions of terms used in the document.
- Supporting Documents: Any additional documents or references supporting the analysis.
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(C) System Design Specification (SDS) Document/Software Design Specification (SDS) Document/ Design Documentation
- The system design specification gives a complete understanding of the details of each system component, its associated algorithms, etc.
- The system design specification documents all the requirements for the system to be implemented.
- The system design document describes how the requirements will finally be implemented/designed.
- It also describes the implementation issues with the help of various system design tools.
- It consists of the final steps of describing the system in detail before the coding starts.
- The system design specification is developed in a two-stage process: –
- In the first step, design specification generally describes the overall architecture of the system at a higher level.
- The second step provides the technical details of low-level design, which will guide the implementer. It describes exactly what the software must perform to meet the requirements of the system.
Tools for Describing System Design
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- Various tools are used to describe the higher-level and lower-level aspects of system design. The following are some of the tools that can be used in the System Design-
- Data Dictionary
- Database Schema
- E-R Model
- Security Model
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The database security model associates users, groups of users, or related applications with database access rights.
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- Trade-off Matrix
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A matrix that is used to describe decision criteria and the relative importance of each decision criterion. This allows comparison of each alternative in a quantifiable term.
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- Decision Table
- Timing Diagram
- Various tools are used to describe the higher-level and lower-level aspects of system design. The following are some of the tools that can be used in the System Design-
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- This diagram describes the timing relationships among various functions and behaviors of each component.
- They are used to explore the behaviors of one or more objects throughout a given period.
- This diagram is specifically useful for describing logic circuits.
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- State Machine Diagram
- Object Interaction Diagram
- Inheritance Diagram
- Aggregation Diagram
- Structure Chart
- Pseudocode
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Architecture of SDS
SDS include-
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- Introduction
- Purpose and Scope of this document
- It includes a full description of the main objectives and the scope of the SDS document is specified.
- Definitions, Acronyms, Abbreviations and References
- Definitions and Abbreviations used are narrated in alphabetic order. This section will include technical books and documents related to design issues.
- Purpose and Scope of this document
- System Architecture Description
- Overview of Modules, Components of the System, and Sub-System
- Structure and Relationships
- In this, interrelationships and dependencies among various components are described.
- Here, the use of structure charts can be useful.
- Detailed Description of Components – It includes
- Introduction
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- Name of the Component
- Purpose and Function
- Sub-routine and Constituents of the component
- Dependencies, Processing Logic including pseudocode
- Data Elements used in the component.
- Appendices
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(D) User-Oriented Documentation/User Manual Document
- A User Manual is an essential resource that guides users in effectively using a product, enhancing their overall experience, and reducing the need for customer support.
- A User Manual is a document that provides instructions and information to end-users on how to effectively use a software application, hardware device, or system.
- It is designed to be accessible to non-technical users and helps them understand the functionality, features, and proper operation of the product.
- A well-crafted user manual enhances user experience, reduces the need for customer support, and ensures users can achieve their goals with the product.
- By providing clear, detailed, and user-friendly documentation, organizations can empower their users to get the most out of their products, leading to higher satisfaction and reduced frustration.
- This document is normally prepared at the end of the software development process.
- A typical User Manual normally contains a Title page, Table of contents, Introduction, Getting Started, Basic Operations, Advanced features, Troubleshooting, Maintenance and Support, Appendices, Index, etc.
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Importance/Purpose of a User Manual
- Guidance: It provides step-by-step instructions on how to use the product effectively and easily.
- Problem-Solving: It helps users to troubleshoot common issues and understand how to fix them.
- Efficiency: It ensures users can quickly find the information they need, reducing frustration and time spent figuring out how to use the product.
- Compliance: It ensures users operate the product safely and in compliance with legal or regulatory requirements.
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Criteria for Creating a User Manual
- Know Your Users/Audience/Clients: For this, tailor the language, level of detail, and examples to the target audience’s technical expertise and needs.
- Use Clear, Simple Language: It is suggested that try to avoid heavy technical jargon and write in a clear, straightforward style that is easy for non-experts to understand.
- Add Visual Aids: If possible, try to use screenshots, diagrams, icons, and other visual elements to supplement the text and process and make instructions easier to follow even by novice users.
- Use Step-by-Step Instructions: To simplify the User Manual, break down tasks into clear, manageable steps, with each step describing a specific action.
- Use Consistent Formatting: It must ensure the consistent use of fonts, headings, bullet points, and numbering to improve readability and understandability about the system/organization.
- Validate Instructions: The accuracy of the instructions should be validated by having them tested by someone unfamiliar with the product to ensure they are clear and complete.
- Regular Update: The manual should be updated regularly to reflect new product versions, features, or changes, and ensure that users always have access to the latest information.
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Types of User Manual Documentation
- Users of the different systems are not of the same category and their requirements vary widely. To, cater to the needs of different classes of users, different types of user documentation are required. The following are various categories of user manuals:
- Introductory Manual: How to get started with the system?
- Functional Description Manual: Describes the functionality of the system.
- User Reference Manual: Details about the system facility.
- System Administrator Guide Manual: How to operate and maintain the system?
- Installation Document Manual: How to install the system?
- Maintenance Manual: How to maintain the installed system?
- Users of the different systems are not of the same category and their requirements vary widely. To, cater to the needs of different classes of users, different types of user documentation are required. The following are various categories of user manuals:
Introductory manual
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- Purpose: The purpose of this document and its intended audience is stated. If there is more than one intended audience, provide information in this section and direct the reader to the correct section(s) for his/her interest.
- Scope of Project: It describes the overview of the product. Explain who could use the product. Overview of the services that it provides. Describe the limitations of the system. Describe any restrictions on using or copying the software and any warranties contractual obligations or disclaimers.
- Glossary: It defines the technical terms used in this document. Do not assume that the reader is an expert.
- References: This references to other documents cited anywhere in this document including references to related project documents. This is usually the only bibliography in the document.
- Overview of Document: The contents and organization of the rest of this document are described.
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- Functional Description Manual/Instructional Manual
- This section should be divided in a manner that will make it user-friendly. It includes –
- System Usage: It provides examples of normal usage such as images of the screen dumps are very useful to provide a look and feel of the product. It provides any necessary background information. The on-line help system is very common for systems today.
- This section should be divided in a manner that will make it user-friendly. It includes –
- User Reference Manual
- List of Services: It provides an alphabetical listing of services provided by the system with references to page numbers in this document where the concerned service is described.
- Error Messages and Recovery: It provides an alphabetical list of all error messages generated by the system and how the user can recover from each of these errors.
- Installation Document Manual
- This manual gives installation information, including the operating environment.
- Maintenance Manual
- The supplier/developer of the software is sometimes different from the software maintenance agency.
- As the software changes, the relevant documents are required to be modified. Documents must reflect all such changes accordingly.
- Maintenance manuals provide precise information to keep our product operating at peak performance.
- This manual is similar to installation manuals, these documents may range from a single sheet to several hundred pages.
- Functional Description Manual/Instructional Manual
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