This document discusses key topics in systems engineering, including:
1) Systems engineering involves procuring, designing, implementing, and maintaining sociotechnical systems that include both technical and human elements.
2) Software systems are part of broader sociotechnical systems and software engineers must consider human, social, and organizational factors.
3) Sociotechnical systems have emergent properties that depend on the interactions between system components and cannot be understood by examining the components individually.
This document discusses software reuse and application frameworks. It covers the benefits of software reuse like accelerated development and increased dependability. Application frameworks provide a reusable architecture for related applications and are implemented by adding components and instantiating abstract classes. Web application frameworks in particular use the model-view-controller pattern to support dynamic websites as a front-end for web applications.
This document discusses configuration management (CM) and version control. It covers topics like version management, system building, change management, and release management. CM is important for software development as it allows tracking of changing software systems and components. Version control systems are key to CM, identifying and storing different versions. They support independent development through a shared repository and private workspaces. Developers check components in and out to make changes separately without interfering with each other.
This document discusses quality management in software development. It covers topics like software quality, standards, reviews/inspections, quality management in agile development, and software measurement. Regarding quality management, the key points are that it provides an independent check on the development process, ensures deliverables meet goals/standards, and the quality team should be independent from developers. Quality plans set quality goals and define assessment processes and standards to apply. Quality management is important for large, complex systems and focuses on establishing a quality culture for smaller systems.
The document discusses chapter 7 of a software engineering textbook which covers design and implementation. It begins by outlining the topics to be covered, including object-oriented design using UML, design patterns, and implementation issues. It then discusses the software design and implementation process, considerations around building versus buying systems, and approaches to object-oriented design using UML.
The document discusses different types of software testing:
- Development testing includes unit, component, and system testing to discover bugs during development. Unit testing involves testing individual program units in isolation.
- Release testing is done by a separate team to test a complete version before public release.
- User testing involves potential users testing the system in their own environment.
The goals of testing are to demonstrate that software meets requirements and to discover incorrect or undesirable behavior to find defects. Different testing types include validation testing to check correct functionality and defect testing to uncover bugs. Both inspections and testing are important and complementary methods in software verification.
The chapter discusses software evolution, including that software change is inevitable due to new requirements, business changes, and errors. It describes how organizations must manage change to existing software systems, which represent huge investments. The majority of large software budgets are spent evolving, rather than developing new, systems. The chapter outlines the software evolution process and different approaches to evolving systems, including addressing urgent changes. It also discusses challenges with legacy systems and their management.
This document provides an introduction to software engineering topics including:
1. What software engineering is, its importance, and the software development lifecycle activities it encompasses.
2. The many different types of software systems that exist and how software engineering approaches vary depending on the application.
3. Key fundamentals of software engineering that apply universally, including managing development processes, dependability, and reusing existing software components.
This document discusses software processes and process models. It covers topics such as the waterfall model, incremental development, integration and configuration, process activities including specification, design, implementation, validation and evolution. It also discusses coping with change through techniques like prototyping and incremental delivery. The key aspects of software process models, activities, and improvement are summarized.
This document discusses software reuse and application frameworks. It covers the benefits of software reuse like accelerated development and increased dependability. Application frameworks provide a reusable architecture for related applications and are implemented by adding components and instantiating abstract classes. Web application frameworks in particular use the model-view-controller pattern to support dynamic websites as a front-end for web applications.
This document discusses configuration management (CM) and version control. It covers topics like version management, system building, change management, and release management. CM is important for software development as it allows tracking of changing software systems and components. Version control systems are key to CM, identifying and storing different versions. They support independent development through a shared repository and private workspaces. Developers check components in and out to make changes separately without interfering with each other.
This document discusses quality management in software development. It covers topics like software quality, standards, reviews/inspections, quality management in agile development, and software measurement. Regarding quality management, the key points are that it provides an independent check on the development process, ensures deliverables meet goals/standards, and the quality team should be independent from developers. Quality plans set quality goals and define assessment processes and standards to apply. Quality management is important for large, complex systems and focuses on establishing a quality culture for smaller systems.
The document discusses chapter 7 of a software engineering textbook which covers design and implementation. It begins by outlining the topics to be covered, including object-oriented design using UML, design patterns, and implementation issues. It then discusses the software design and implementation process, considerations around building versus buying systems, and approaches to object-oriented design using UML.
The document discusses different types of software testing:
- Development testing includes unit, component, and system testing to discover bugs during development. Unit testing involves testing individual program units in isolation.
- Release testing is done by a separate team to test a complete version before public release.
- User testing involves potential users testing the system in their own environment.
The goals of testing are to demonstrate that software meets requirements and to discover incorrect or undesirable behavior to find defects. Different testing types include validation testing to check correct functionality and defect testing to uncover bugs. Both inspections and testing are important and complementary methods in software verification.
The chapter discusses software evolution, including that software change is inevitable due to new requirements, business changes, and errors. It describes how organizations must manage change to existing software systems, which represent huge investments. The majority of large software budgets are spent evolving, rather than developing new, systems. The chapter outlines the software evolution process and different approaches to evolving systems, including addressing urgent changes. It also discusses challenges with legacy systems and their management.
This document provides an introduction to software engineering topics including:
1. What software engineering is, its importance, and the software development lifecycle activities it encompasses.
2. The many different types of software systems that exist and how software engineering approaches vary depending on the application.
3. Key fundamentals of software engineering that apply universally, including managing development processes, dependability, and reusing existing software components.
This document discusses software processes and process models. It covers topics such as the waterfall model, incremental development, integration and configuration, process activities including specification, design, implementation, validation and evolution. It also discusses coping with change through techniques like prototyping and incremental delivery. The key aspects of software process models, activities, and improvement are summarized.
This document provides an overview of topics in chapter 13 on security engineering. It discusses security and dependability, security dimensions of confidentiality, integrity and availability. It also outlines different security levels including infrastructure, application and operational security. Key aspects of security engineering are discussed such as secure system design, security testing and assurance. Security terminology and examples are provided. The relationship between security and dependability factors like reliability, availability, safety and resilience is examined. The document also covers security in organizations and the role of security policies.
The document discusses architectural design and various architectural concepts. It covers topics like architectural design decisions, architectural views using different models, common architectural patterns like MVC and layered architectures, application architectures, and how architectural design is concerned with organizing a software system and identifying its main structural components and relationships.
This document summarizes key concepts from Chapter 15 on resilience engineering. It discusses resilience as the ability of systems to maintain critical services during disruptions like failures or cyberattacks. Resilience involves recognizing issues, resisting failures when possible, and recovering quickly through activities like redundancy. The document also covers sociotechnical resilience, where human and organizational factors are considered, and characteristics of resilient organizations like responsiveness, monitoring, anticipation, and learning.
The document discusses agile software development methods. It covers topics like agile methods, techniques, and project management. Rapid and iterative development is emphasized to quickly adapt to changing requirements. Methods like Extreme Programming (XP) use practices like user stories, test-driven development, pair programming, and continuous refactoring to develop working software in short iterations.
The document discusses reliability engineering and fault tolerance. It covers topics like availability, reliability requirements, fault-tolerant architectures, and reliability measurement. It defines key terms like faults, errors, and failures. It also describes techniques for achieving reliability like fault avoidance, fault detection, and fault tolerance. Specific architectures discussed include redundant systems and protection systems that can take emergency action if failures occur.
System modeling involves creating abstract models of a system from different perspectives, such as context, interactions, structure, and behavior. These models help analysts understand system functionality and communicate with customers. Context models show a system's external environment and relationships. Interaction models, such as use case and sequence diagrams, depict how users and systems interact. Structural models, like class diagrams, represent a system's internal organization. Behavioral models, including activity and state diagrams, illustrate a system's dynamic response to events or data. Model-driven engineering aims to generate implementation from system models.
Architectural design involves identifying major system components and their communications. Architectural views provide different perspectives of the system, such as conceptual, logical, process, and development views. Common architectural patterns include model-view-controller, layered, client-server, and pipe-and-filter architectures. Application architectures define common structures for transaction processing, information, and language processing systems.
The document discusses dependability in systems. It covers topics like dependability properties, sociotechnical systems, redundancy and diversity, and dependable processes. Dependability reflects how trustworthy a system is and includes attributes like reliability, availability, and security. Dependability is important because system failures can have widespread impacts. Both hardware and software failures and human errors can cause systems to fail. Techniques like redundancy, diversity, and formal methods can help improve dependability. Regulation is also discussed as many critical systems require approval from regulators.
This document discusses component-based software engineering (CBSE). It covers topics like components and component models, CBSE processes, and component composition. The key points are:
- CBSE relies on reusable software components with well-defined interfaces to improve reuse. Components are more abstract than classes.
- Essentials of CBSE include independent, interface-specified components; standards for integration; and middleware for interoperability.
- CBSE is based on principles like independence, hidden implementations, and replaceability through maintained interfaces.
The document discusses architectural design, including:
- Architectural design determines how a software system is organized and structured. It identifies the main components and relationships.
- Architectural views show different perspectives of a system, such as logical, process, development, and physical views. Common patterns like model-view-controller and layered architectures are also covered.
- Architectural decisions impact system characteristics like performance, security, and maintainability. Common application architectures are also discussed.
This document discusses service-oriented software engineering and RESTful web services. It covers topics like service-oriented architectures, RESTful services, service engineering, and service composition. Key points include that services are reusable components that are loosely coupled and platform independent. Service-oriented approaches allow for opportunistic construction of new services and pay-per-use models. Web services standards like SOAP, WSDL, and WS-BPEL are also discussed. The document provides an example of a service-oriented in-car information system.
This document discusses systems of systems and complexity. It begins by defining systems of systems and providing examples. Key characteristics of systems of systems include operational and managerial independence of elements, and evolutionary development. The document then covers sources of complexity, including technical, managerial and governance complexity. It discusses how reductionism has traditionally been used to manage complexity in engineering but has limitations for large systems of systems.
The document discusses various types of software testing:
- Development testing includes unit, component, and system testing to discover defects.
- Release testing is done by a separate team to validate the software meets requirements before release.
- User testing involves potential users testing the system in their own environment.
The goals of testing are validation, to ensure requirements are met, and defect testing to discover faults. Automated unit testing and test-driven development help improve test coverage and regression testing.
The document discusses several topics related to software project management including risk management, managing people, and teamwork. It describes the key activities of a project manager including planning, risk assessment, people management, reporting, and proposal writing. Specific risks at the project, product, and business levels are defined and strategies for risk identification, analysis, planning, monitoring, and mitigation are outlined. Effective people management is also emphasized, including motivating team members through satisfying different human needs and personality types. A case study demonstrates how addressing an individual team member's motivation issues can improve project outcomes.
Ian Sommerville, Software Engineering, 9th Edition Ch2Mohammed Romi
This document summarizes key aspects of software processes and models. It discusses the basic activities involved in software development like specification, design, implementation, validation and evolution. It describes process models like waterfall, incremental development and reuse-oriented processes. The waterfall model involves sequential phases while incremental development interleaves activities. Validation includes testing stages from unit to system level. The document also covers designing for change and evolution.
Software evolution involves making ongoing changes to software systems to address new requirements, fix errors, and improve performance. There are several approaches to managing software evolution, including maintenance, reengineering, refactoring, and legacy system management. Key considerations for legacy systems include assessing their business value and quality to determine whether they should be replaced, transformed, or maintained.
This chapter discusses system modeling and different types of models used, including:
- Context models which illustrate the operational context of a system.
- Interaction models which model interactions between a system and its environment.
- Structural models which display the organization of a system's components.
- Behavioral models which model a system's dynamic behavior in response to events or data.
- Model-driven engineering is discussed as an approach where models rather than code are the primary outputs.
This document provides an overview of software reuse techniques discussed in Chapter 16, including:
1) Application frameworks which provide reusable skeleton designs through abstract and concrete classes;
2) Software product lines which allow generic applications to be adapted through configuration, component selection, and specialization for different requirements;
3) COTS (commercial off-the-shelf) product reuse where pre-existing software systems can be customized through deployment configuration without changing source code.
The document discusses agile software development methods. It covers topics like agile methods, techniques, and project management. Agile development aims to rapidly develop and deliver working software through iterative processes, customer collaboration, and responding to changing requirements. Extreme programming (XP) is an influential agile method that uses practices like test-driven development, pair programming, frequent refactoring, and user stories for requirements specification. The key principles of agile methods are also outlined.
This document provides an overview of topics covered in Chapter 7 on software design and implementation, including object-oriented design using UML, design patterns, implementation issues, and open source development. It discusses the design and implementation process, build vs buy approaches, object-oriented design processes involving system models, and key activities like defining system context, identifying objects and interfaces. Specific examples are provided for designing a wilderness weather station system.
System engineering involves determining operational requirements and modeling relationships between elements like hardware, software, and people to accomplish goals. It can focus on business processes or product development. The engineering process follows a hierarchy from overall objectives to domain specifications to element implementations. It is iterative to adapt to changing needs. Business process engineering derives data, application, and technology architectures, while product engineering defines architectures and infrastructure for software, hardware, data, and people components.
The document discusses system engineering and defines key concepts. System engineering focuses on designing complex engineering projects by defining customer needs early and documenting required functionality. It uses a waterfall model with little iteration between phases due to hardware costs. System engineering involves interaction between different engineering disciplines that require negotiation due to different vocabularies. The system engineering process includes stating problems, investigating alternatives, modeling the system, integrating elements, launching the system, and assessing performance.
This document provides an overview of topics in chapter 13 on security engineering. It discusses security and dependability, security dimensions of confidentiality, integrity and availability. It also outlines different security levels including infrastructure, application and operational security. Key aspects of security engineering are discussed such as secure system design, security testing and assurance. Security terminology and examples are provided. The relationship between security and dependability factors like reliability, availability, safety and resilience is examined. The document also covers security in organizations and the role of security policies.
The document discusses architectural design and various architectural concepts. It covers topics like architectural design decisions, architectural views using different models, common architectural patterns like MVC and layered architectures, application architectures, and how architectural design is concerned with organizing a software system and identifying its main structural components and relationships.
This document summarizes key concepts from Chapter 15 on resilience engineering. It discusses resilience as the ability of systems to maintain critical services during disruptions like failures or cyberattacks. Resilience involves recognizing issues, resisting failures when possible, and recovering quickly through activities like redundancy. The document also covers sociotechnical resilience, where human and organizational factors are considered, and characteristics of resilient organizations like responsiveness, monitoring, anticipation, and learning.
The document discusses agile software development methods. It covers topics like agile methods, techniques, and project management. Rapid and iterative development is emphasized to quickly adapt to changing requirements. Methods like Extreme Programming (XP) use practices like user stories, test-driven development, pair programming, and continuous refactoring to develop working software in short iterations.
The document discusses reliability engineering and fault tolerance. It covers topics like availability, reliability requirements, fault-tolerant architectures, and reliability measurement. It defines key terms like faults, errors, and failures. It also describes techniques for achieving reliability like fault avoidance, fault detection, and fault tolerance. Specific architectures discussed include redundant systems and protection systems that can take emergency action if failures occur.
System modeling involves creating abstract models of a system from different perspectives, such as context, interactions, structure, and behavior. These models help analysts understand system functionality and communicate with customers. Context models show a system's external environment and relationships. Interaction models, such as use case and sequence diagrams, depict how users and systems interact. Structural models, like class diagrams, represent a system's internal organization. Behavioral models, including activity and state diagrams, illustrate a system's dynamic response to events or data. Model-driven engineering aims to generate implementation from system models.
Architectural design involves identifying major system components and their communications. Architectural views provide different perspectives of the system, such as conceptual, logical, process, and development views. Common architectural patterns include model-view-controller, layered, client-server, and pipe-and-filter architectures. Application architectures define common structures for transaction processing, information, and language processing systems.
The document discusses dependability in systems. It covers topics like dependability properties, sociotechnical systems, redundancy and diversity, and dependable processes. Dependability reflects how trustworthy a system is and includes attributes like reliability, availability, and security. Dependability is important because system failures can have widespread impacts. Both hardware and software failures and human errors can cause systems to fail. Techniques like redundancy, diversity, and formal methods can help improve dependability. Regulation is also discussed as many critical systems require approval from regulators.
This document discusses component-based software engineering (CBSE). It covers topics like components and component models, CBSE processes, and component composition. The key points are:
- CBSE relies on reusable software components with well-defined interfaces to improve reuse. Components are more abstract than classes.
- Essentials of CBSE include independent, interface-specified components; standards for integration; and middleware for interoperability.
- CBSE is based on principles like independence, hidden implementations, and replaceability through maintained interfaces.
The document discusses architectural design, including:
- Architectural design determines how a software system is organized and structured. It identifies the main components and relationships.
- Architectural views show different perspectives of a system, such as logical, process, development, and physical views. Common patterns like model-view-controller and layered architectures are also covered.
- Architectural decisions impact system characteristics like performance, security, and maintainability. Common application architectures are also discussed.
This document discusses service-oriented software engineering and RESTful web services. It covers topics like service-oriented architectures, RESTful services, service engineering, and service composition. Key points include that services are reusable components that are loosely coupled and platform independent. Service-oriented approaches allow for opportunistic construction of new services and pay-per-use models. Web services standards like SOAP, WSDL, and WS-BPEL are also discussed. The document provides an example of a service-oriented in-car information system.
This document discusses systems of systems and complexity. It begins by defining systems of systems and providing examples. Key characteristics of systems of systems include operational and managerial independence of elements, and evolutionary development. The document then covers sources of complexity, including technical, managerial and governance complexity. It discusses how reductionism has traditionally been used to manage complexity in engineering but has limitations for large systems of systems.
The document discusses various types of software testing:
- Development testing includes unit, component, and system testing to discover defects.
- Release testing is done by a separate team to validate the software meets requirements before release.
- User testing involves potential users testing the system in their own environment.
The goals of testing are validation, to ensure requirements are met, and defect testing to discover faults. Automated unit testing and test-driven development help improve test coverage and regression testing.
The document discusses several topics related to software project management including risk management, managing people, and teamwork. It describes the key activities of a project manager including planning, risk assessment, people management, reporting, and proposal writing. Specific risks at the project, product, and business levels are defined and strategies for risk identification, analysis, planning, monitoring, and mitigation are outlined. Effective people management is also emphasized, including motivating team members through satisfying different human needs and personality types. A case study demonstrates how addressing an individual team member's motivation issues can improve project outcomes.
Ian Sommerville, Software Engineering, 9th Edition Ch2Mohammed Romi
This document summarizes key aspects of software processes and models. It discusses the basic activities involved in software development like specification, design, implementation, validation and evolution. It describes process models like waterfall, incremental development and reuse-oriented processes. The waterfall model involves sequential phases while incremental development interleaves activities. Validation includes testing stages from unit to system level. The document also covers designing for change and evolution.
Software evolution involves making ongoing changes to software systems to address new requirements, fix errors, and improve performance. There are several approaches to managing software evolution, including maintenance, reengineering, refactoring, and legacy system management. Key considerations for legacy systems include assessing their business value and quality to determine whether they should be replaced, transformed, or maintained.
This chapter discusses system modeling and different types of models used, including:
- Context models which illustrate the operational context of a system.
- Interaction models which model interactions between a system and its environment.
- Structural models which display the organization of a system's components.
- Behavioral models which model a system's dynamic behavior in response to events or data.
- Model-driven engineering is discussed as an approach where models rather than code are the primary outputs.
This document provides an overview of software reuse techniques discussed in Chapter 16, including:
1) Application frameworks which provide reusable skeleton designs through abstract and concrete classes;
2) Software product lines which allow generic applications to be adapted through configuration, component selection, and specialization for different requirements;
3) COTS (commercial off-the-shelf) product reuse where pre-existing software systems can be customized through deployment configuration without changing source code.
The document discusses agile software development methods. It covers topics like agile methods, techniques, and project management. Agile development aims to rapidly develop and deliver working software through iterative processes, customer collaboration, and responding to changing requirements. Extreme programming (XP) is an influential agile method that uses practices like test-driven development, pair programming, frequent refactoring, and user stories for requirements specification. The key principles of agile methods are also outlined.
This document provides an overview of topics covered in Chapter 7 on software design and implementation, including object-oriented design using UML, design patterns, implementation issues, and open source development. It discusses the design and implementation process, build vs buy approaches, object-oriented design processes involving system models, and key activities like defining system context, identifying objects and interfaces. Specific examples are provided for designing a wilderness weather station system.
System engineering involves determining operational requirements and modeling relationships between elements like hardware, software, and people to accomplish goals. It can focus on business processes or product development. The engineering process follows a hierarchy from overall objectives to domain specifications to element implementations. It is iterative to adapt to changing needs. Business process engineering derives data, application, and technology architectures, while product engineering defines architectures and infrastructure for software, hardware, data, and people components.
The document discusses system engineering and defines key concepts. System engineering focuses on designing complex engineering projects by defining customer needs early and documenting required functionality. It uses a waterfall model with little iteration between phases due to hardware costs. System engineering involves interaction between different engineering disciplines that require negotiation due to different vocabularies. The system engineering process includes stating problems, investigating alternatives, modeling the system, integrating elements, launching the system, and assessing performance.
Design and implementation of a computerized goods transportation systemOvercomer Michael
This document presents a project report on the design and implementation of a computerized goods transportation management system for a university course. It includes an introduction outlining the background and objectives of the study, as well as the existing problems with manual systems. It then discusses the benefits of computerized systems and importance of the work. The document is organized by traditional project report sections which will cover the existing system analysis, proposed system design, implementation, testing and documentation.
Fault tolerance is important for distributed systems to continue functioning in the event of partial failures. There are several phases to achieving fault tolerance: fault detection, diagnosis, evidence generation, assessment, and recovery. Common techniques include replication, where multiple copies of data are stored at different sites to increase availability if one site fails, and check pointing, where a system's state is periodically saved to stable storage so the system can be restored to a previous consistent state if a failure occurs. Both techniques have limitations around managing consistency with replication and overhead from checkpointing communications and storage requirements.
This document provides an introduction and overview of key topics in software engineering. It discusses what software engineering is, the importance and costs of software development, different types of software projects and applications, and issues like complexity, security and scale that affect software. It also introduces software engineering processes, methods, and ethics. Common questions about the field are addressed. The document is the first chapter of a book on software engineering.
This chapter discusses distributed software engineering and distributed systems. It covers topics like distributed system characteristics including resource sharing, openness, concurrency, scalability and fault tolerance. Some key issues with distributed systems are their complexity, lack of single control, and independence of parts. The chapter addresses design issues for distributed systems such as transparency, openness, scalability, security, quality of service, and failure management. It also covers models of interaction, middleware, and client-server computing.
The document summarizes topics related to real-time software engineering including embedded system design, architectural patterns for real-time software, timing analysis, and real-time operating systems. It discusses key characteristics of embedded systems like responsiveness, the need to respond to stimuli within specified time constraints, and how real-time systems are often modeled as cooperating processes controlled by a real-time executive. The document also outlines common architectural patterns for real-time systems including observe and react, environmental control, and process pipeline.
The document discusses project planning, including topics like software pricing, plan-driven development, project scheduling, and agile planning. It covers the different stages of planning, from initial proposals to ongoing development. Project planning involves breaking work into parts, anticipating problems, and communicating the plan. Regular updates allow the plan to reflect new information and changes throughout the project.
This document discusses safety engineering for systems that contain software. It covers topics like safety-critical systems, safety requirements, and safety engineering processes. Safety is defined as a system's ability to operate normally and abnormally without harm. For safety-critical systems like aircraft or medical devices, software is often used for control and monitoring, so software safety is important. Hazard identification, risk assessment, and specifying safety requirements to mitigate risks are key parts of the safety engineering process. The goal is to design systems where failures cannot cause injury, death or environmental damage.
This document discusses software processes and models. It covers the following key points:
1. Software processes involve activities like specification, design, implementation, validation and evolution to develop software systems. Common process models include waterfall, incremental development and reuse-oriented development.
2. Processes need to cope with inevitable changes. This can involve prototyping to avoid rework or using incremental development and delivery to more easily accommodate changes.
3. The Rational Unified Process is a modern process model with phases for inception, elaboration, construction and transition. It advocates iterative development and managing requirements and quality.
This document discusses systems engineering and the process of developing sociotechnical systems. It covers key topics like conceptual design, procurement, and the stages of systems engineering. Sociotechnical systems are complex and have emergent properties due to interactions between technical, human, and organizational factors. Success is difficult to define as stakeholders may have different views. Conceptual design develops an initial vision of the system purpose before detailed requirements. Procurement decisions involve choosing between custom development or commercial off-the-shelf systems.
This document discusses sociotechnical systems and systems engineering. It defines sociotechnical systems as systems that include both technical systems (e.g. hardware and software) as well as operational processes and people. Sociotechnical systems have emergent properties that depend on the interactions between system components. They are also non-deterministic since human behavior introduces unpredictability. Developing sociotechnical systems requires an interdisciplinary approach involving areas like software engineering, organizational design, and human factors.
This document provides an overview of sociotechnical systems. It discusses how software systems are part of broader systems that include human, social, and organizational aspects. It describes the layers in a sociotechnical systems stack from equipment to society. Emergent properties, non-determinism, and differing views of success from stakeholders are characteristics of these complex systems. Systems engineering is the process of procuring, developing, and maintaining sociotechnical systems over their lifecycle.
The document discusses systems and system engineering. It defines a system as a collection of interrelated components working together to achieve a common goal. There are two types of systems - technical systems which only include hardware and software, and socio-technical systems which also include people. Emergent properties are properties of the whole system that cannot be derived from individual components and depend on their relationships. Examples are reliability, security, and usability. System engineering is concerned with specifying, designing, implementing, validating, deploying and maintaining socio-technical systems. The key stages of the system engineering process are requirements definition, system design, and integration and testing.
Socio-technical system: Essential characteristics of socio technical systems,
Emergent System Properties, Systems Engineering, Components of system such 9
as organization, people and computers.
Critical system: Types of critical system, A simple safety critical system, Availability and Reliability, Safety and Security of Software systems.
Requirements Engineering Processes: Feasibility study, Requirements elicitation and analysis, Requirements Validations.
System Models: Models and its types, Context Models, Behavioural Models,
Data Models, Object Models, Structured Methods.
A socio-technical system is a system that includes both technical components like hardware and software as well as human and organizational elements. Socio-technical systems exhibit emergent properties that depend on the relationships between components and how the system operates within an organizational context. The design and evolution of socio-technical systems involves multiple disciplines working together using systems engineering processes to define requirements, design system architecture, develop subsystems, integrate the overall system, and support ongoing operation and maintenance.
1. A socio-technical system includes technical components like hardware and software as well as people and organizational processes. It has emergent properties that depend on the relationships between components and cannot be understood by examining individual parts alone.
2. Systems engineering involves specifying, designing, developing, and testing socio-technical systems through processes like requirements definition, system design, sub-system development, and integration. It must account for human and organizational factors.
3. Legacy systems refer to existing socio-technical systems that are crucial but use outdated technology. They constrain business processes and are costly to maintain.
This chapter discusses dependable systems and covers several topics related to ensuring system dependability. It defines key dependability properties like availability, reliability, safety and security. It discusses causes of system failures and the importance of dependability. It also covers approaches to improving dependability like redundancy, diversity, and formal methods. Dependable processes with activities like requirements reviews, testing and inspections are also discussed.
This document discusses software processes and activities. It covers topics like software process models, process activities, and process improvement. Some key points include: a software process involves specification, design, implementation, validation and evolution; process models include waterfall, incremental development, and configuration/integration; activities involve specification, design/implementation, validation and evolution; and testing is a major validation activity involving component, system and customer testing.
This document provides an overview of software processes and models. It discusses topics like specification, design, implementation, validation, evolution, and process improvement. Common process models like waterfall, incremental development, and integration/configuration are described. The document also covers process activities, coping with change through techniques like prototyping and incremental delivery, and process improvement through models like the spiral model.
this is for software engineering and design used to make attention of what you gonnal do in your next session i hope you to enjoy by reading this lecture
The document discusses software processes and activities. It describes common process models like waterfall, incremental development, and configuration management. The key activities involved in most processes are specification, development, validation, and evolution. Specification defines system requirements while development includes design, implementation, and debugging. Validation ensures the system meets requirements through testing. Processes also evolve to adapt to changing needs.
Cloud computing has gained popularity over the years, some organizations are using some form of cloud
computing to enhance their business operations while reducing infrastructure costs and gaining more
agility by deploying applications and making changes to applications easily. Cloud computing systems just
like any other computer system are prone to failure, these failures are due to the distributed and complex
nature of the cloud computing platforms.
Cloud computing has gained popularity over the years, some organizations are using some form of cloud
computing to enhance their business operations while reducing infrastructure costs and gaining more
agility by deploying applications and making changes to applications easily. Cloud computing systems just
like any other computer system are prone to failure, these failures are due to the distributed and complex
nature of the cloud computing platforms.
Cloud computing systems need to be built for failure to ensure that they continue operating even if the
cloud system has an error. The errors should be masked from the cloud users to ensure that users continue
accessing the cloud services and this intern leads to cloud consumers gaining confidence in the availability
and reliability of cloud services.
In this paper, we propose the use of N-Modular redundancy to design and implement failure-free clouds
This chapter discusses dependable systems and covers topics like dependability properties, sociotechnical systems, redundancy and diversity, dependable processes, and formal methods for dependability. It defines dependability as reflecting a user's degree of trust in a system operating as expected without failure. Dependability encompasses attributes like reliability, availability, and security. Formal methods that use mathematical modeling can help reduce errors and improve dependability. Developing dependable systems also requires consideration of the sociotechnical context and dependable engineering processes.
The document discusses software process models. It describes the waterfall model, which involves requirements analysis, design, implementation, testing, and maintenance phases completed sequentially. However, the waterfall model is inflexible and doesn't adapt well to changing requirements. The document then introduces incremental development as an alternative, delivering the system in prioritized increments to allow for adapting to changes more easily.
This document discusses key concepts in systems engineering. It explains that a system is a collection of components working together toward a common goal. Properties like reliability emerge from the relationships between components and can only be assessed once a system is integrated. The systems engineering process is described, including requirements definition, design, development, integration, installation, operation, evolution, and decommissioning. Challenges like coordinating across disciplines and accounting for changes over a system's lifetime are also outlined. The conclusion emphasizes that systems engineering is difficult and requires cooperation across engineering fields.
The document discusses various topics related to software engineering including:
1) How early days of software development have affected modern practices.
2) Definitions of software engineering from different sources.
3) The stages of software design including problem analysis, solution identification, and abstraction description.
4) Object-oriented design principles like information hiding, independent objects, and service-based communication.
This document contains a chapter from a course manual on Object Oriented Analysis and Design. The chapter discusses the inherent complexity of software systems. It identifies four main reasons for this complexity: 1) the complexity of the problem domain and changing requirements, 2) the difficulty of managing large software development teams, 3) the flexibility enabled by software which can lead to more demanding requirements, and 4) the challenges of characterizing the behavior of discrete systems. Software systems can range from simple to highly complex, depending on factors like purpose, lifespan, number of users, and role in research.
IRJET- Software Architecture and Software DesignIRJET Journal
This document discusses software architecture and design. It defines software architecture as the strategic design of a system that addresses global requirements, while software design is the tactical design that addresses local requirements of what a solution does. The document outlines key characteristics of software architecture like serverless and event-driven architectures. It also discusses principles of software design like the single responsibility principle. Finally, it explains that while architecture focuses on structure and high-level design, design delves into implementation details, and there is overlap between the two.
- Traditionally, separate teams handled software development, release, and support, which caused delays. The DevOps approach combines these roles into a single multi-skilled team.
- Three factors drove DevOps adoption: Agile reduced development time but introduced bottlenecks; Amazon improved reliability with single teams; software could be released as a service.
- DevOps benefits include faster deployment, reduced risk, and faster repair through collaboration between development and operations teams.
Covers security and privacy issues for software product developers including attacks and defenses, encryption, authentication, authorisation and data protection
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Introduces some fundamentals of cloud based software and discusses architectural issues for product developers. Covers containers, databases and cloud architecture choices
The document discusses software products and product engineering. It defines software products as generic systems that provide functionality to a range of customers, from business systems to personal apps. Product engineering methods have evolved from custom software engineering techniques. The key aspects of product development are that there is no external customer generating requirements, and rapid delivery is important to capture the market. Product managers are responsible for planning, development, and marketing software products throughout their lifecycle.
Facilitation Skills - When to Use and Why.pptxKnoldus Inc.
In this session, we will discuss the world of Agile methodologies and how facilitation plays a crucial role in optimizing collaboration, communication, and productivity within Scrum teams. We'll dive into the key facets of effective facilitation and how it can transform sprint planning, daily stand-ups, sprint reviews, and retrospectives. The participants will gain valuable insights into the art of choosing the right facilitation techniques for specific scenarios, aligning with Agile values and principles. We'll explore the "why" behind each technique, emphasizing the importance of adaptability and responsiveness in the ever-evolving Agile landscape. Overall, this session will help participants better understand the significance of facilitation in Agile and how it can enhance the team's productivity and communication.
Must Know Postgres Extension for DBA and Developer during MigrationMydbops
Mydbops Opensource Database Meetup 16
Topic: Must-Know PostgreSQL Extensions for Developers and DBAs During Migration
Speaker: Deepak Mahto, Founder of DataCloudGaze Consulting
Date & Time: 8th June | 10 AM - 1 PM IST
Venue: Bangalore International Centre, Bangalore
Abstract: Discover how PostgreSQL extensions can be your secret weapon! This talk explores how key extensions enhance database capabilities and streamline the migration process for users moving from other relational databases like Oracle.
Key Takeaways:
* Learn about crucial extensions like oracle_fdw, pgtt, and pg_audit that ease migration complexities.
* Gain valuable strategies for implementing these extensions in PostgreSQL to achieve license freedom.
* Discover how these key extensions can empower both developers and DBAs during the migration process.
* Don't miss this chance to gain practical knowledge from an industry expert and stay updated on the latest open-source database trends.
Mydbops Managed Services specializes in taking the pain out of database management while optimizing performance. Since 2015, we have been providing top-notch support and assistance for the top three open-source databases: MySQL, MongoDB, and PostgreSQL.
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Supercell is the game developer behind Hay Day, Clash of Clans, Boom Beach, Clash Royale and Brawl Stars. Learn how they unified real-time event streaming for a social platform with hundreds of millions of users.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
In our second session, we shall learn all about the main features and fundamentals of UiPath Studio that enable us to use the building blocks for any automation project.
📕 Detailed agenda:
Variables and Datatypes
Workflow Layouts
Arguments
Control Flows and Loops
Conditional Statements
💻 Extra training through UiPath Academy:
Variables, Constants, and Arguments in Studio
Control Flow in Studio
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In migrating a massive, business-critical database, the Chief Technology Officer's (CTO) perspective is crucial. This endeavor requires meticulous planning, risk assessment, and a structured approach to ensure minimal disruption and maximum data integrity during the transition. The CTO's role involves overseeing technical strategies, evaluating the impact on operations, ensuring data security, and coordinating with relevant teams to execute a seamless migration while mitigating potential risks. The focus is on maintaining continuity, optimising performance, and safeguarding the business's essential data throughout the migration process
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The best thing about databases is that they always work as intended, and never suffer any downtime. You'll never see a system go offline because of a database outage. In this talk, Bo Ingram -- staff engineer at Discord and author of ScyllaDB in Action --- dives into an outage with one of their ScyllaDB clusters, showing how a stressed ScyllaDB cluster looks and behaves during an incident. You'll learn about how to diagnose issues in your clusters, see how external failure modes manifest in ScyllaDB, and how you can avoid making a fault too big to tolerate.
LF Energy Webinar: Carbon Data Specifications: Mechanisms to Improve Data Acc...DanBrown980551
This LF Energy webinar took place June 20, 2024. It featured:
-Alex Thornton, LF Energy
-Hallie Cramer, Google
-Daniel Roesler, UtilityAPI
-Henry Richardson, WattTime
In response to the urgency and scale required to effectively address climate change, open source solutions offer significant potential for driving innovation and progress. Currently, there is a growing demand for standardization and interoperability in energy data and modeling. Open source standards and specifications within the energy sector can also alleviate challenges associated with data fragmentation, transparency, and accessibility. At the same time, it is crucial to consider privacy and security concerns throughout the development of open source platforms.
This webinar will delve into the motivations behind establishing LF Energy’s Carbon Data Specification Consortium. It will provide an overview of the draft specifications and the ongoing progress made by the respective working groups.
Three primary specifications will be discussed:
-Discovery and client registration, emphasizing transparent processes and secure and private access
-Customer data, centering around customer tariffs, bills, energy usage, and full consumption disclosure
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CNSCon 2024 Lightning Talk: Don’t Make Me Impersonate My IdentityCynthia Thomas
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For senior executives, successfully managing a major cyber attack relies on your ability to minimise operational downtime, revenue loss and reputational damage.
Indeed, the approach you take to recovery is the ultimate test for your Resilience, Business Continuity, Cyber Security and IT teams.
Our Cyber Recovery Wargame prepares your organisation to deliver an exceptional crisis response.
Event date: 19th June 2024, Tate Modern
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kafka-streams-cassandra-state-store' is a drop-in Kafka Streams State Store implementation that persists data to Apache Cassandra.
By moving the state to an external datastore the stateful streams app (from a deployment point of view) effectively becomes stateless. This greatly improves elasticity and allows for fluent CI/CD (rolling upgrades, security patching, pod eviction, ...).
It also can also help to reduce failure recovery and rebalancing downtimes, with demos showing sporty 100ms rebalancing downtimes for your stateful Kafka Streams application, no matter the size of the application’s state.
As a bonus accessing Cassandra State Stores via 'Interactive Queries' (e.g. exposing via REST API) is simple and efficient since there's no need for an RPC layer proxying and fanning out requests to all instances of your streams application.
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To enable an on-demand comparison of the DBaaS landscape we present the benchANT DBaaS Navigator, an open DBaaS comparison platform for management and deployment features, costs, and performance. The DBaaS Navigator is an open data platform that enables the comparison of over 20 DBaaS providers for the relational and NoSQL databases.
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Northern Engraving | Modern Metal Trim, Nameplates and Appliance PanelsNorthern Engraving
What began over 115 years ago as a supplier of precision gauges to the automotive industry has evolved into being an industry leader in the manufacture of product branding, automotive cockpit trim and decorative appliance trim. Value-added services include in-house Design, Engineering, Program Management, Test Lab and Tool Shops.
Multivendor cloud production with VSF TR-11 - there and back again
Ch19 systems engineering
1. Chapter 19 – Systems Engineering
Chapter 19 Systems Engineering 126/11/2014
2. Topics covered
Sociotechnical systems
Conceptual design
Systems procurement
System development
System operation and evolution
Chapter 19 Systems Engineering 226/11/2014
3. Systems
Software engineering is not an isolated activity but is part
of a broader systems engineering process.
Software systems are therefore not isolated systems but
are essential components of broader systems that have
a human, social or organizational purpose.
Example
Wilderness weather system is part of broader weather recording
and forecasting systems
These include hardware and software, forecasting processes,
system users, the organizations that depend on weather
forecasts, etc.
Chapter 19 Systems Engineering 326/11/2014
4. Types of system
Technical computer-based systems
Include hardware and software but not humans or organizational
processes.
Off the shelf applications, control systems, etc.
Sociotechnical systems
Include technical systems plus people who use and manage
these systems and the organizations that own the systems and
set policies for their use.
Business systems, command and control systems, etc.
Chapter 19 Systems Engineering 426/11/2014
5. Systems engineering
Procuring, specifying, designing, implementing,
validating, deploying and maintaining sociotechnical
systems.
Concerned with the services provided by the system,
constraints on its construction and operation and the
ways in which it is used to fulfil its purpose or purposes.
Chapter 19 Systems Engineering 526/11/2014
6. Systems and software engineering
Software is now the dominant element in all enterprise
systems. Software engineers have to play a more active
part in high-level systems decision making if the system
software is to be dependable and developed on time and
to budget.
As a software engineer, it helps if you have a broader
awareness of how software interacts with other hardware
and software systems, and the human, social and
organizational factors that affect the ways in which
software is used.
Chapter 19 Systems Engineering 626/11/2014
7. Stages of systems engineering
Chapter 19 Systems Engineering 726/11/2014
8. Systems engineering stages
Conceptual design
Sets out the purpose of the system, why it is needed and the
high-level features that users might expect to see in the system
Procurement or acquisition
The conceptual design is developed so that decisions about the
contract for the system development can be made.
Development
Hardware and software is engineered and operational processes
defined.
Operation
The system is deployed and used for its intended purpose.
Chapter 19 Systems Engineering 826/11/2014
9. Stages of systems engineering
Chapter 19 Systems Engineering 926/11/2014
11. Inter-disciplinary working
Communication difficulties
Different disciplines use the same terminology to mean different
things. This can lead to misunderstandings about what will be
implemented.
Differing assumptions
Each discipline makes assumptions about what can and can’t be
done by other disciplines.
Professional boundaries
Each discipline tries to protect their professional boundaries and
expertise and this affects their judgments on the system.
Chapter 19 Systems Engineering 1126/11/2014
13. Sociotechnical systems
Large-scale systems that do not just include software
and hardware but also people, processes and
organizational policies.
Sociotechnical systems are often ‘systems of systems’
i.e. are made up of a number of independent systems.
Systems of systems are covered in Chapter 20
The boundaries of sociotechnical system are subjective
rather than objective
Different people see the system in different ways
Chapter 19 Systems Engineering 1326/11/2014
14. Layered structure of sociotechnical systems
Chapter 19 Systems Engineering 1426/11/2014
15. Systems and organizations
Sociotechnical systems are used within organizations
and are therefore profoundly affected by the
organizational environment in which they are used.
Failure to take this environment into account when
designing the system is likely to lead to user
dissatisfaction and system rejection.
Chapter 19 Systems Engineering 1526/11/2014
17. Organizational affects
Process changes
Systems may require changes to business processes so training
may be required. Significant changes may be resisted by users.
Job changes
Systems may de-skill users or cause changes to the way they
work. The status of individuals may be affected by a new system.
Organizational policies
The proposed system may not be consistent with current
organizational policies.
Organizational politics
Systems may change the political power structure in an
organization. Those that control the system have more power.
Chapter 19 Systems Engineering 1726/11/2014
18. Complex systems
A system may include software, mechanical, electrical
and electronic hardware and be operated by people.
System components are dependent on other
system components.
The properties and behaviour of system components
are inextricably inter-mingled. This leads to
complexity.
Complexity is the reason why sociotechnical systems
have emergent properties, are non-deterministic and
have subjective success criteria.
26/11/2014 Chapter 19 Systems Engineering 18
19. Socio-technical system characteristics
Emergent properties
Properties of the system of a whole that depend on the system
components and their relationships.
Non-deterministic
They do not always produce the same output when presented
with the same input because the systems’s behaviour is partially
dependent on human operators.
Complex relationships with organisational objectives
The extent to which the system supports organisational
objectives does not just depend on the system itself.
26/11/2014 Chapter 19 Systems Engineering 19
20. Emergent properties
Properties of the system as a whole rather than
properties that can be derived from the properties of
components of a system
Emergent properties are a consequence of the
relationships between system components
They can therefore only be assessed and measured
once the components have been integrated into a
system
26/11/2014 Chapter 19 Systems Engineering 20
21. Examples of emergent properties
Property Description
Reliability System reliability depends on component reliability but unexpected
interactions can cause new types of failures and therefore affect the reliability
of the system.
Repairability This property reflects how easy it is to fix a problem with the system once it
has been discovered. It depends on being able to diagnose the problem,
access the components that are faulty, and modify or replace these
components.
Security The security of the system (its ability to resist attack) is a complex property
that cannot be easily measured. Attacks may be devised that were not
anticipated by the system designers and so may defeat built-in safeguards.
Usability This property reflects how easy it is to use the system. It depends on the
technical system components, its operators, and its operating environment.
Volume The volume of a system (the total space occupied) varies depending on how
the component assemblies are arranged and connected.
Chapter 19 Systems Engineering 2126/11/2014
22. Types of emergent property
Functional properties
These appear when all the parts of a system work together to
achieve some objective. For example, a bicycle has the
functional property of being a transportation device once it has
been assembled from its components.
Non-functional emergent properties
Examples are reliability, performance, safety, and security. These
relate to the behaviour of the system in its operational
environment. They are often critical for computer-based systems
as failure to achieve some minimal defined level in these
properties may make the system unusable.
26/11/2014 Chapter 19 Systems Engineering 22
23. Reliability as an emergent property
Because of component inter-dependencies,
faults can be propagated through the system.
System failures often occur because of
unforeseen inter-relationships between
components.
It is practically impossible to anticipate all
possible component relationships.
Software reliability measures may give a false
picture of the overall system reliability.
26/11/2014 Chapter 19 Systems Engineering 23
24. Influences on reliability
Hardware reliability
What is the probability of a hardware component failing and how
long does it take to repair that component?
Software reliability
How likely is it that a software component will produce an
incorrect output. Software failure is usually distinct from
hardware failure in that software does not wear out.
Operator reliability
How likely is it that the operator of a system will make an error?
Failures are not independent and they propagate from
one level to another.
26/11/2014 Chapter 19 Systems Engineering 24
26. Reliability and system context
System reliability depends on the context where the
system is used.
A system that is reliable in one environment may be less
reliable in a different environment because the physical
conditions (e.g. the temperature) and the mode of
operation is different.
Chapter 19 Systems Engineering 2626/11/2014
27. Non-determinism
A deterministic system is one where a given sequence of
inputs will always produce the same sequence of
outputs.
Software systems are deterministic; systems that include
humans are non-deterministic
A socio-technical system will not always produce the same
sequence of outputs from the same input sequence
Human elements
• People do not always behave in the same way
System changes
• System behaviour is unpredictable because of frequent changes to
hardware, software and data.
Chapter 19 Systems Engineering 2726/11/2014
28. Success criteria
Complex systems are developed to address ‘wicked
problems’ – problems where there cannot be a complete
specification.
Different stakeholders see the problem in different ways
and each has a partial understanding of the issues
affecting the system.
Consequently, different stakeholders have their own
views about whether or not a system is ‘successful’
Success is a judgment and cannot be objectively measured.
Success is judged using the effectiveness of the system when
deployed rather than judged against the original reasons for
procuement.
Chapter 19 Systems Engineering 2826/11/2014
29. Conflicting views of success
The Mentcare system is designed to support multiple,
conflicting goals
Improve quality of care.
Provide better information and care costs and so increase
revenue.
Fundamental conflict
Doctors and nurses had to provide additional information over
and above that required for clinical purposes.
They had less time to interact with patients, so quality of care
reduced. System was not a success.
However, managers had better reports
System was a success from a managerial perspective.
Chapter 19 Systems Engineering 2926/11/2014
31. Conceptual design
Investigate the feasibility of an idea and develop that
idea to create an overall vision of a system.
Conceptual design precedes and overlaps with
requirements engineering
May involve discussions with users and other stakeholders and
the identification of critical requirements
The aim of conceptual design is to create a high-level
system description that communicates the system
purpose to non-technical decision makers.
Chapter 19 Systems Engineering 3126/11/2014
33. Concept formulation
Refine an initial statement of needs and work out what type of
system is most likely to meet the needs of system stakeholders
Problem understanding
Discuss with stakeholders how they do their work, what is and
isn’t important to them, what they like and don’t like about
existing systems
System proposal development
Set out ideas for possible systems (maybe more than one)
Chapter 19 Systems Engineering 3326/11/2014
34. Feasibility study
Look at comparable systems that have been developed
elsewhere (if any) and assess whether or not the proposed
system could be implemented using current hardware and
software technologies
System structure development
Develop an outline architecture for the system, identifying (where
appropriate) other systems that may be reused
System vision document
Document the results of the conceptual design in a readable,
non-technical way. Should include a short summary and more
detailed appendices.
Chapter 19 Systems Engineering 3426/11/2014
35. User stories for presentation of system vision
Chapter 19 Systems Engineering 35
Digital art
Jill is an S2 pupil at a secondary school in Dundee. She has a smart phone of
her own and the family has a shared Samsung tablet and a Dell laptop
computer. At school, Jill signs on to the school computer and is presented with
a personalized Glow+ environment, which includes a range of services, some
chosen by her teachers and some she has chosen herself from the Glow app
library.
She is working on a Celtic art project and she uses Google to research a range
of art sites. She sketches out some designs on paper then uses the camera on
her phone to photograph what she has done and uploads this using the school
wifi to her personal Glow+ space. Her homework is to complete the design and
write a short commentary on her ideas.
26/11/2014
36. User stories (2)
Chapter 19 Systems Engineering 36
At home, she uses the family tablet to sign on to Glow+ and she then uses
an artwork ‘app’ to process her photograph and to extend the work, add
colour, etc.
She finishes this and to complete the work she moves to her home laptop
to type up her commentary. She uploads the finished work to Glow+ and
sends a message to her art teacher that it is available for review. Her
teacher looks at this in a free period before Jill’s next art class using a
school tablet and, in class, discusses the work with Jill.
After the discussion, the teacher and Jill decide that the work should be
shared and they publish it to the school web pages that show examples of
students’ work. In addition, the work is included in Jill’s e-portfolio – her
record of schoolwork from age 3 to 18.
26/11/2014
38. System procurement
Acquiring a system (or systems) to meet some identified
organizational need.
Before procurement, decisions are made on:
Scope of the system
System budgets and timescales
High-level system requirements
Based on this information, decisions are made on
whether to procure a system, the type of system and the
potential system suppliers.
Chapter 19 Systems Engineering 3826/11/2014
39. Decision drivers
The state of other organizational systems and whether or
not they need to be replaced
The need to comply with external regulations
External competition
Business re-organization
Available budget
Chapter 19 Systems Engineering 3926/11/2014
40. Procurement and development
It is usually necessary to develop a conceptual design
document and high-level requirements before
procurement
You need a specification to let a contract for system
development
The specification may allow you to buy a commercial off-the-
shelf (COTS) system. Almost always cheaper than developing a
system from scratch
Large complex systems usually consist of a mix of off the
shelf and specially designed components. The
procurement processes for these different types of
component are usually different.
26/11/2014 Chapter 19 Systems Engineering 40
41. Types of system
Off-the-shelf applications that may be used without
change and which need only minimal configuration for
use.
Configurable application or ERP systems that have to be
modified or adapted for use either by modifying the code
or by using inbuilt configuration features, such as
process definitions and rules.
Custom systems that have to be designed and
implemented specially for use.
Chapter 19 Systems Engineering 4126/11/2014
43. Procurement issues
Organizations often have an approved and
recommended set of application software that has been
checked by the IT department.
It is usually possible to buy or acquire open source software from
this set directly without the need for detailed justification.
There are no detailed requirements and the users adapt to the
features of the chosen application.
Off-the-shelf components do not usually match
requirements exactly.
Choosing a system means that you have to find the closest
match between the system requirements and the facilities
offered by off-the-shelf systems.
26/11/2014 Chapter 19 Systems Engineering 43
44. Procurement issues (2)
When a system is to be built specially, the specification
of requirements is part of the contract for the system
being acquired.
It is therefore a legal as well as a technical document.
The requirements document is critical and procurement
processes of this type usually take a considerable amount of
time.
For public sector systems especially, there are detailed
rules and regulations that affect the procurement of
systems.
These force the development of detailed requirements and make
agile development difficult
Chapter 19 Systems Engineering 4426/11/2014
45. Procurement issues (3)
For application systems that require change or for
custom systems there is usually a contract negotiation
period where the customer and supplier negotiate the
terms and conditions for the development of the system.
During this process, requirements changes may be agreed to
reduce the overall costs and avoid some development problems.
Chapter 19 Systems Engineering 4526/11/2014
46. Procurement decisions
Decisions made at the procurement stage of the systems
engineering process are critical for later stages in that
process.
Poor procurement decisions often lead to problems such as late
delivery of a system and the development of systems that are
unsuited to their operational environment.
If the wrong system or the wrong supplier is chosen then the
technical processes of system and software engineering become
more complex.
Chapter 19 Systems Engineering 4626/11/2014
48. System development
Usually follows a plan-driven approach because of the
need for parallel development of different parts of the
system
Little scope for iteration between phases because hardware
changes are very expensive. Software may have to compensate
for hardware problems.
Inevitably involves engineers from different disciplines
who must work together
Much scope for misunderstanding here.
As explained, different disciplines use a different vocabulary and
much negotiation is required. Engineers may have personal
agendas to fulfil.
26/11/2014 Chapter 19 Systems Engineering 48
50. The system development process
Requirements engineering
The process of refining, analysing and documenting the high-
level and business requirements identified in the conceptual
design
Architectural design
Establishing the overall architecture of the system, identifying
components and their relationships
Requirements partitioning
Deciding which subsystems (identified in the system
architecture) are responsible for implementing the system
requirements
26/11/2014 Chapter 19 Systems Engineering 50
51. The system development process (2)
Subsystem engineering
Developing the software components of the system, configuring
off-the-shelf hardware and software, defining the operational
processes for the system and re-designing business processes
System integration
Putting together system elements to create a new system
System testing
The whole system is tested to discover problems
System deployment
the process of making the system available to its users,
transferring data from existing systems and establishing
communications with other systems in the environment
26/11/2014 Chapter 19 Systems Engineering 51
52. Requirements and design
Requirements engineering and system design are
inextricably linked.
Constraints posed by the system’s environment and
other systems limit design choices so the actual design
to be used may be a requirement.
Initial design may be necessary to structure the
requirements.
As you do design, you learn more about the
requirements.
26/11/2014 Chapter 19 Systems Engineering 52
54. Subsystem engineering
Typically parallel projects developing the hardware,
software and communications.
May involve some application systems procurement.
Lack of communication across implementation teams
can cause problems.
There may be a bureaucratic and slow mechanism for
proposing system changes, which means that the
development schedule may be extended because of the
need for rework.
26/11/2014 Chapter 19 Systems Engineering 54
55. System integration
The process of putting hardware, software and
people together to make a system.
Should ideally be tackled incrementally so that sub-
systems are integrated one at a time.
The system is tested as it is integrated.
Interface problems between sub-systems are usually
found at this stage.
May be problems with uncoordinated deliveries
of system components.
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56. System delivery and deployment
After completion, the system has to be installed in the
customer’s environment
Environmental assumptions may be incorrect;
May be human resistance to the introduction of a new system;
System may have to coexist with alternative systems for some
time;
May be physical installation problems (e.g. cabling problems);
Data cleanup may be required;
Operator training has to be identified.
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58. System operation
Operational processes are the processes involved in
using the system for its defined purpose.
For new systems, these processes may have to be
designed and tested and operators trained in the use of
the system.
Operational processes should be flexible to allow
operators to cope with problems and periods of
fluctuating workload.
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59. Problems with operation automation
It is likely to increase the technical complexity of the
system because it has to be designed to cope with all
anticipated failure modes. This increases the costs and
time required to build the system.
Automated systems are inflexible. People are adaptable
and can cope with problems and unexpected situations.
This means that you do not have to anticipate everything
that could possibly go wrong when you are specifying
and designing the system
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60. System evolution
Large systems have a long lifetime. They must evolve to
meet changing requirements.
Evolution is inherently costly
Changes must be analysed from a technical and business
perspective;
Sub-systems interact so unanticipated problems can arise;
There is rarely a rationale for original design decisions;
System structure is corrupted as changes are made to it.
Existing systems which must be maintained are
sometimes called legacy systems.
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61. Factors that affect system lifetimes
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Factor Rationale
Investment cost The costs of a systems engineering project may be tens or
even hundreds of millions of dollars. These costs can only be
justified if the system can deliver value to an organization for
many years.
Loss of
expertise
As businesses change and restructure to focus on their core
activities, they often lose engineering expertise. This may
mean that they lack the ability to specify the requirements for
a new system.
Replacement
cost
The cost of replacing a large system is very high. Replacing
an existing system can only be justified if this leads to
significant cost savings over the existing system.
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62. Factors that affect system lifetimes
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Factor Rationale
Return on
investment
If a fixed budget is available for systems engineering,
spending this on new systems in some other area of the
business may lead to a higher return on investment than
replacing an existing system.
Risks of change Systems are an inherent part of business operations and
the risks of replacing existing systems with new systems
cannot be justified. The danger with a new system is that
things can go wrong in the hardware, software and
operational processes. The potential costs of these
problems for the business may be so high that they cannot
take the risk of system replacement.
System
dependencies
Other systems may depend on a system and making
changes to these other systems to accommodate a
replacement system may be impractical.
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Proposed changes have to be analyzed very carefully
from a business and a technical perspective.
Subsystems are never completely independent so
changes to a subsystem may have side-effects that
adversely affect other subsystems.
Reasons for original design decisions are often
unrecorded. Those responsible for the system evolution
have to work out why these decisions were made.
As systems age, their structure becomes corrupted by
change so the costs of making further changes
increases.
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64. Key points
Systems engineering is concerned with all aspects of
specifying, buying, designing and testing complex
sociotechnical systems.
Sociotechnical systems include computer hardware,
software and people, and are situated within an
organization. They are designed to support
organizational or business goals and objectives.
The emergent properties of a system are characteristics
of the system as a whole rather than of its component
parts. They include properties such as performance,
reliability, usability, safety and security.
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65. Key points
The fundamental systems engineering processes are
conceptual systems design, system procurement,
system development and system operation.
Conceptual systems design is a key activity where high
level system requirements and a vision of the operational
system is developed.
System procurement covers all of the activities involved
in deciding what system to buy and who should supply
that system. Different procurement processes are used
for off-the-shelf application systems, configurable COTS
systems and custom systems.
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66. Key points
System development processes include requirements
specification, design, construction, integration and
testing.
When a system is put into use, the operational
processes and the system itself inevitably change to
reflect changes to the business requirements and the
system’s environment.
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