"A clean design is more easily modified as requirements change or as more is learned about what parts of the code consume significant amounts of execution time. A 'clever' design that fails to work or to run fast enough can often be salvaged only at great cost. Efficiency does not have to be sacrificed in the interest of writing readable code - rather, writing readable code is often the only way to ensure efficient programs that are also easy to maintain and modify." (Brian W Kernighan & Phillip J Plauger, "The Elements of Programming Style", 1974)
"A good top-down design avoids bugs in several ways. First, the clarity of structure and representation makes the precise statement of requirements and functions of the modules easier. Second, the partitioning and independence of modules avoids system bugs. Third, the suppression of detail makes flaws in the structure more apparent. Fourth, the design can be tested at each of its refinement steps, so testing can start earlier and focus on the proper level of detail at each step." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"Far be it from me to suggest that all changes in customer objectives and requirements must, can, or should be incorporated in the design. Clearly a threshold has to be established, and it must get higher and higher as development proceeds, or no product ever appears." (Fred P Brooks, "The Mythical Man-Month: Essays", 1975)
"The beginning of wisdom for a programmer is to recognize the difference between getting his program to work and getting it right. A program which does not work is undoubtedly wrong; but a program which does work is not necessarily right. It may still be wrong because it is hard to understand; or because it is hard to maintain as the problem requirements change; or because its structure is different from the structure of the problem; or because we cannot be sure that it does indeed work." (Michael A Jackson, "Principles of Program Design", 1975)
"The hardest single part of building a software system is deciding precisely what to build." (Frederick P. Brooks, "The Mythical Man-Month", 1975)
"[Enterprise Architecture is] the set of descriptive representations (i. e., models) that are relevant for describing an Enterprise such that it can be produced to management's requirements (quality) and maintained over the period of its useful life." (John Zachman, 1987)
"The hardest part of the software task is arriving at a complete and consistent specification, and much of the essence of building a program is in fact the debugging of the specification." (Frederick P Brooks, "No Silver Bullet", 1987)
"In programming, it’s often the buts in the specification that kill you." (Boris Beizer, "Software Testing Techniques", 1990)
"Object-oriented analysis is a method of analysis that examines requirements from the perspective of the classes and objects found in the vocabulary of the problem domain."(Grady Booch, "Object-oriented design: With Applications", 1991)
"The source code is often the only accurate description of the software. On many projects, the only documentation available to programmers is the code itself. Requirements specifications and design documents can go out of date, but the source code is always up to date. Consequently, it's imperative that the code be of the highest possible quality." (Steve C McConnell," Code Complete: A Practical Handbook of Software Construction", 1993)
"Users can work with analysts and object designers to formulate and tune system requirements. People from business, analytical and object design disciplines can come together, learn from each other and generate meaningful descriptions of systems that are to be built. Each participant and each project has slightly different concerns and needs. Practical application of use cases can go a long way to improve our ability to deliver just what the customer ordered. (Rebecca Wirfs-Brock, "Designing scenarios: Making the case for a use case framework", 1993)
"Our experience with designing and analyzing large and complex software-intensive systems has led us to recognize the role of business and organization in the design of the system and in its ultimate success or failure. Systems are built to satisfy an organization's requirements (or assumed requirements in the case of shrink-wrapped products). These requirements dictate the system's performance, availability, security, compatibility with other systems, and the ability to accommodate change over its lifetime. The desire to satisfy these goals with software that has the requisite properties influences the design choices made by a software architect." (Len Bass et al, "Software Architecture in Practice", 1998)
"Agile development methodologies promise higher customer satisfaction, lower defect rates, faster development times and a solution to rapidly changing requirements. Plan-driven approaches promise predictability, stability, and high assurance. However, both approaches have shortcomings that, if left unaddressed, can lead to project failure. The challenge is to balance the two approaches to take advantage of their strengths and compensate for their weaknesses." (Barry Boehm & Richard Turner, "Observations on balancing discipline and agility", Agile Development Conference, 2003)
"The aim of architectural design is to prepare overall specifications, derived from the needs and desires of the user, for subsequent design and construction stages. The first task for the architect in each design project is thus to determine what the real needs and desires of the user are […]" (George J Klir & Doug Elias, "Architecture of Systems Problem Solving" 2nd Ed, 2003)
"The software architecture of a system or a family of systems has one of the most significant impacts on the quality of an organization's enterprise architecture. While the design of software systems concentrates on satisfying the functional requirements for a system, the design of the software architecture for systems concentrates on the nonfunctional or quality requirements for systems. These quality requirements are concerns at the enterprise level. The better an organization specifies and characterizes the software architecture for its systems, the better it can characterize and manage its enterprise architecture. By explicitly defining the systems software architectures, an organization will be better able to reflect the priorities and trade-offs that are important to the organization in the software that it builds." (James McGovern et al, "A Practical Guide to Enterprise Architecture", 2004)
"Enterprise architecture is the organizing logic for business processes and IT infrastructure reflecting the integration and standardization requirements of a company's operation model. […] The key to effective enterprise architecture is to identify the processes, data, technology, and customer interfaces that take the operating model from vision to reality." (Jeanne W Ross et al, "Enterprise architecture as strategy: creating a foundation for business", 2006)
"The role of conceptual modelling in information systems development during all these decades is seen as an approach for capturing fuzzy, ill-defined, informal 'real-world' descriptions and user requirements, and then transforming them to formal, in some sense complete, and consistent conceptual specifications." (Janis A Burbenko jr., "From Information Algebra to Enterprise Modelling and Ontologies", Conceptual Modelling in Information Systems Engineering, 2007)
"Writing the spec, a document that lays out copiously detailed instructions for the programmer, is a necessary step in any software building enterprise where the ultimate user of the product is not the same person as the programmer. The spec translates requirements - the set of goals or desires the software developer’s customers lay out - into detailed marching orders for the programmer to follow." (Scott Rosenberg, "Dreaming in Code", 2007)
"If the discipline of requirements specification has taught us anything, it is that well-specified requirements are as formal as code and can act as executable tests of that code!" (Robert C Martin, "Clean Code: A Handbook of Agile Software Craftsmanship", 2008)
"Nothing has a more profound and long-term degrading effect upon a development project than bad code. Bad schedules can be redone, bad requirements can be redefined. Bad team dynamics can be repaired. But bad code rots and ferments, becoming an inexorable weight that drags the team down." (Robert C Martin, "Clean Code: A Handbook of Agile Software Craftsmanship", 2008)
"A good system design is based on a sound conceptual model (architecture). A system design that has no conceptual structure and little logic to its organization is ultimately going to be unsuccessful. Good architecture will address all the requirements of the system at the right level of abstraction." (Vasudeva Varma, "Software Architecture: A Case Based Approach", 2009)
"Design is the bridging activity between gathering and implementation of software requirements that satisfies the required needs. […] The fundamental goal of design is to reduce the number of dependencies between modules, thus reducing the complexity of the system. This is also known as coupling; lesser the coupling the better is the design. On the other hand, higher the binding between elements within a module (known as cohesion) the better is the design." (Vasudeva Varma, "Software Architecture: A Case Based Approach", 2009)
"Taking a systems approach means paying close attention to results, the reasons we build a system. Architecture must be grounded in the client’s/user’s/customer’s purpose. Architecture is not just about the structure of components. One of the essential distinguishing features of architectural design versus other sorts of engineering design is the degree to which architectural design embraces results from the perspective of the client/user/customer. The architect does not assume some particular problem formulation, as 'requirements' is fixed. The architect engages in joint exploration, ideally directly with the client/user/customer, of what system attributes will yield results worth paying for." (Mark W Maier, "The Art Systems of Architecting" 3rd Ed., 2009)
"Agile approaches to software development consider design and implementation to be the central activities in the software process. They incorporate other activities, such as requirements elicitation and testing, into design and implementation. By contrast, a plan-driven approach to software engineering identifies separate stages in the software process with outputs associated with each stage." (Ian Sommerville, "Software Engineering" 9th Ed., 2011)
"Agile methods universally rely on an incremental approach to software specification, development, and delivery. They are best suited to application development where the system requirements usually change rapidly during the development process. They are intended to deliver working software quickly to customers, who can then propose new and changed requirements to be included in later iterations of the system. They aim to cut down on process bureaucracy by avoiding work that has dubious long-term value and eliminating documentation that will probably never be used." (Ian Sommerville, "Software Engineering" 9th Ed., 2011)
"Models are used during the requirements engineering process to help derive the requirements for a system, during the design process to describe the system to engineers implementing the system and after implementation to document the system’s structure and operation." (Ian Sommerville, "Software Engineering" 9th Ed., 2011)
"Software systems do not exist in isolation. They are used in a social and organizational context and software system requirements may be derived or constrained by that context. Satisfying these social and organizational requirements is often critical for the success of the system. One reason why many software systems are delivered but never used is that their requirements do not take proper account of how the social and organizational context affects the practical operation of the system."(Ian Sommerville, "Software Engineering" 9th Ed., 2011)
"Creating mockups to communicate is not intrinsically a bad idea. But, as we are subject to confirmation bias, there’s always a risk that we will stop at our first design attempt and become reluctant to ask if there are better ways to achieve the same goals. Making these first ideas very detailed; putting them into a document; and especially blessing that document with the label 'requirements' are all moves which make further revision less likely, and put us more at risk from confirmation bias." (Laurent Bossavit, "The Leprechauns of Software Engineering", 2015)
