Computer- aided software engineering - Wikipedia. Computer- aided software engineering (CASE) is the domain of software tools used to design and implement applications. CASE tools are similar to and were partly inspired by computer- aided design (CAD) tools used to design hardware products. CASE tools are used to develop software that is high- quality, defect- free, and maintainable. Several papers by Daniel Teichroew fired a whole generation of enthusiasts with the potential of automated systems development. His Problem Statement Language / Problem Statement Analyzer (PSL/PSA) tool was a CASE tool although it predated the term. By extending the range of metadata held, the attributes of an application could be held within a dictionary and used at runtime. However, the active dictionary did not provide a graphical representation of any of the metadata. It was the linking of the concept of a dictionary holding analysts' metadata, as derived from the use of an integrated set of techniques, together with the graphical representation of such data that gave rise to the earlier versions of CASE. Graphi. Text's successor product, Design. Aid, was the first microprocessor- based tool to logically and semantically evaluate software and system design diagrams and build a data dictionary. Under the direction of Albert F. While Design. Aid ran on Convergent Technologies and later Burroughs Ngen networked microcomputers, Index launched Excelerator on the IBM PC/AT platform. While, at the time of launch, and for several years, the IBM platform did not support networking or a centralized database as did the Convergent Technologies or Burroughs machines, the allure of IBM was strong, and Excelerator came to prominence. Hot on the heels of Excelerator were a rash of offerings from companies such as Knowledgeware (James Martin, Fran Tarkenton and Don Addington), Texas Instrument's IEF and Andersen Consulting's FOUNDATION toolset (DESIGN/1, INSTALL/1, FCP). CASE tools were at their peak in the early 1. IBM has entered into relationships with Bachman Information Systems, Index Technology Corporation, and Knowledgeware wherein selected products from these vendors will be marketed through an IBM complementary marketing program to provide offerings that will help to achieve complete life- cycle coverage. Many of the leaders of the CASE market of the early 1. Computer Associates, including IEW, IEF, ADW, Cayenne, and Learmonth & Burchett Management Systems (LBMS). The other trend that led to the evolution of CASE tools was the rise of object- oriented methods and tools. Most of the various tool vendors added some support for object- oriented methods and tools. To explore how the systems development life cycle is used in the enterprise, here are some additional resources: Varying SDLC methodologies among development teams: Software development life cycle (SDLC) methodologies have their own advantages, tools and. The Role of Higher Education in Economic Development Higher Education Alliance for the Rock River Region Contributors Northern Illinois. What is a data dictionary What is its role in the systems development process? SAVE CANCEL already exists. Would you like to merge this question into it? MERGE CANCEL already exists as an alternate of this question. Would you like to make it the. Computer Aided Software Engineering (CASE) tools offer many benefits for developers building large-scale systems. As spiralling user requirements continue to drive system complexity to new levels, CASE tools enable software engineers to abstract away from. In addition new products arose that were designed from the bottom up to support the object- oriented approach. Andersen developed its project Eagle as an alternative to Foundation. Several of the thought leaders in object- oriented development each developed their own methodology and CASE tool set: Jacobsen, Rumbaugh, Booch, etc. Eventually, these diverse tool sets and methods were consolidated via standards led by the Object Management Group (OMG). The OMG's Unified Modelling Language (UML) is currently widely accepted as the industry standard for object- oriented modeling. CASE software. Fuggetta classified CASE software into 3 categories. They can be divided into the following categories: Business and Analysis modeling. Graphical modeling tools. E. g., E/R modeling, object modeling, etc. Development. Design and construction phases of the life- cycle. Debugging environments. E. g., GNU Debugger. Verification and validation. Analyze code and specifications for correctness, performance, etc. Configuration management. Control the check- in and check- out of repository objects and files. E. g., SCCS, CMS. Metrics and measurement. Analyze code for complexity, modularity (e. Manage project plans, task assignments, scheduling. Another common way to distinguish CASE tools is the distinction between Upper CASE and Lower CASE. Need to look at the life cycle of a use case from a number of different but complementary perspectives. It is this unification of the software development process that makes use cases such a powerful technique. Participants in Systems Development Stakeholders Individuals who are beneficiaries of the systems development effort. Users Individuals who interact with the system regularly. Systems Analyst Professional who specializes in analyzing and designing business. Upper CASE Tools support business and analysis modeling. They support traditional diagrammatic languages such as ER diagrams, Data flow diagram, Structure charts, Decision Trees, Decision tables, etc. Lower CASE Tools support development activities, such as physical design, debugging, construction, testing, component integration, maintenance, and reverse engineering. All other activities span the entire life- cycle and apply equally to upper and lower CASE. Hence they achieve: a homogeneous and consistent interface (presentation integration). An example workbench is Microsoft's Visual Basic programming environment. It incorporates several development tools: a GUI builder, smart code editor, debugger, etc. Most commercial CASE products tended to be such workbenches that seamlessly integrated two or more tools. Workbenches also can be classified in the same manner as tools; as focusing on Analysis, Development, Verification, etc. This contrasts with tools that focus on one specific task or a specific part of the life- cycle. CASE environments are classified by Fuggetta as follows. Loosely coupled collections of tools. These typically build on operating system workbenches such as the Unix Programmer's Workbench or the VMS VAX set. They typically perform integration via piping or some other basic mechanism to share data and pass control. The strength of easy integration is also one of the drawbacks. Simple passing of parameters via technologies such as shell scripting can't provide the kind of sophisticated integration that a common repository database can. Fourth generation. These environments are also known as 4. GL standing for fourth generation language environments due to the fact that the early environments were designed around specific languages such as Visual Basic. They were the first environments to provide deep integration of multiple tools. Typically these environments were focused on specific types of applications. For example, user- interface driven applications that did standard atomic transactions to a relational database. Examples are Informix 4. GL, and Focus. Language- centered. Environments based on a single often object- oriented language such as the Symbolics Lisp Genera environment or Visual. Works Smalltalk from Parcplace. In these environments all the operating system resources were objects in the object- oriented language. This provides powerful debugging and graphical opportunities but the code developed is mostly limited to the specific language. For this reason, these environments were mostly a niche within CASE. Their use was mostly for prototyping and R& D projects. A common core idea for these environments was the model- view- controller user interface that facilitated keeping multiple presentations of the same design consistent with the underlying model. The MVC architecture was adopted by the other types of CASE environments as well as many of the applications that were built with them. Integrated. These environments are an example of what most IT people tend to think of first when they think of CASE. Environments such as IBM's AD/Cycle, Andersen Consulting's FOUNDATION, the ICL CADES system, and DEC Cohesion. These environments attempt to cover the complete life- cycle from analysis to maintenance and provide an integrated database repository for storing all artifacts of the software process. The integrated software repository was the defining feature for these kinds of tools. They provided multiple different design models as well as support for code in heterogenous languages. One of the main goals for these types of environments was . These environments were also typically associated with a particular methodology for software development. For example the FOUNDATION CASE suite from Andersen was closely tied to the Andersen Method/1 methodology. Process- centered. This is the most ambitious type of integration. These environments attempt to not just formally specify the analysis and design objects of the software process but the actual process itself and to use that formal process to control and guide software projects. Examples are East, Enterprise II, Process Wise, Process Weaver, and Arcadia. These environments were by definition tied to some methodology since the software process itself is part of the environment and can control many aspects of tool invocation. In practice, the distinction between workbenches and environments was flexible. Visual Basic for example was a programming workbench but was also considered a 4. GL environment by many. The features that distinguished workbenches from environments were deep integration via a shared repository or common language and some kind of methodology (integrated and process- centered environments) or domain (4. GL) specificity. Organizations usually have to tailor and adopt methodologies and tools to their specific requirements. Doing so may require significant effort to integrate both divergent technologies as well as divergent methods. For example, before the adoption of the UML standard the diagram conventions and methods for designing object- oriented models were vastly different among followers of Jacobsen, Booch, Rumbaugh, etc. Unrealistic expectations. The proponents of CASE technology. In reality no such technology can do that and if organizations approach CASE with unrealistic expectations they will inevitably be disappointed. Inadequate training. As with any new technology, CASE requires time to train people in how to use the tools and to get up to speed with them. CASE projects can fail if practitioners are not given adequate time for training or if the first project attempted with the new technology is itself highly mission critical and fraught with risk. Inadequate process control. CASE provides significant new capabilities to utilize new types of tools in innovative ways. Without the proper process guidance and controls these new capabilities can cause significant new problems as well. Annual Westinghouse computer symposium; 6. Systems development life cycle - Wikipedia. Model of the systems development life cycle, highlighting the maintenance phase. The systems development life cycle (SDLC), also referred to as the application development life- cycle, is a term used in systems engineering, information systems and software engineering to describe a process for planning, creating, testing, and deploying an information system. Like anything that is manufactured on an assembly line, an SDLC aims to produce high- quality systems that meet or exceed customer expectations, based on customer requirements, by delivering systems which move through each clearly defined phase, within scheduled time frames and cost estimates. To manage this level of complexity, a number of SDLC models or methodologies have been created, such as . Agile methodologies, such as XP and Scrum, focus on lightweight processes which allow for rapid changes (without necessarily following the pattern of SDLC approach) along the development cycle. Iterative methodologies, such as Rational Unified Process and dynamic systems development method, focus on limited project scope and expanding or improving products by multiple iterations. Sequential or big- design- up- front (BDUF) models, such as waterfall, focus on complete and correct planning to guide large projects and risks to successful and predictable results. Other models, such as anamorphic development, tend to focus on a form of development that is guided by project scope and adaptive iterations of feature development. In project management a project can be defined both with a project life cycle (PLC) and an SDLC, during which slightly different activities occur. According to Taylor (2. The systems development life cycle, according to Elliott & Strachan & Radford (2. Information systems activities revolved around heavy data processing and number crunching routines. Ever since, according to Elliott (2. It consists of a set of steps or phases in which each phase of the SDLC uses the results of the previous one. The SDLC adheres to important phases that are essential for developers, such as planning, analysis, design, and implementation, and are explained in the section below. It includes evaluation of present system, information gathering, feasibility study and request approval. A number of SDLC models have been created: waterfall, fountain, spiral, build and fix, rapid prototyping, incremental, synchronize and stabilize. The oldest of these, and the best known, is the waterfall model: a sequence of stages in which the output of each stage becomes the input for the next. These stages can be characterized and divided up in different ways, including the following. Even if a problem refers only to a small segment of the organization itself, you need to find out what the objectives of the organization itself are. Then you need to see how the problem being studied fits in with them. Propose alternative solutions: In digging into the organization's objectives and specific problems, you may have already covered some solutions. Alternate proposals may come from interviewing employees, clients, suppliers, and/or consultants. You can also study what competitors are doing. With this data, you will have three choices: leave the system as is, improve it, or develop a new system. Describe the costs and benefits. Systems analysis, requirements definition: Defines project goals into defined functions and operation of the intended application. It is the process of gathering and interpreting facts, diagnosing problems and recommending improvements to the system. Analyzes end- user information needs and also removes any inconsistencies and incompleteness in these requirements. A series of steps followed by the developer are. This is also where changes are made to initial software. It involves continuous evaluation of the system in terms of its performance. Evaluation: Some companies do not view this as an official stage of the SDLC, while others consider it to be an extension of the maintenance stage, and may be referred to in some circles as post- implementation review. This is where the system that was developed, as well as the entire process, is evaluated. Some of the questions that need to be answered include: does the newly implemented system meet the initial business requirements and objectives? Is the system reliable and fault- tolerant? Does the system function according to the approved functional requirements? In addition to evaluating the software that was released, it is important to assess the effectiveness of the development process. If there are any aspects of the entire process, or certain stages, that management is not satisfied with, this is the time to improve. Evaluation and assessment is a difficult issue. However, the company must reflect on the process and address weaknesses. Disposal: In this phase, plans are developed for discarding system information, hardware and software in making the transition to a new system. The purpose here is to properly move, archive, discard or destroy information, hardware and software that is being replaced, in a manner that prevents any possibility of unauthorized disclosure of sensitive data. The disposal activities ensure proper migration to a new system. Particular emphasis is given to proper preservation and archival of data processed by the previous system. All of this should be done in accordance with the organization's security requirements. The tasks and work products for each phase are described in subsequent chapters. However, the phases are interdependent. Depending upon the size and complexity of the project, phases may be combined or may overlap. During this step, we must consider all current priorities that would be affected and how they should be handled. Before any system planning is done, a feasibility study should be conducted to determine if creating a new or improved system is a viable solution. This will help to determine the costs, benefits, resource requirements, and specific user needs required for completion. The development process can only continue once management approves of the recommendations from the feasibility study. This step involves breaking down the system in different pieces to analyze the situation, analyzing project goals, breaking down what needs to be created and attempting to engage users so that definite requirements can be defined. In systems design, the design functions and operations are described in detail, including screen layouts, business rules, process diagrams and other documentation. The output of this stage will describe the new system as a collection of modules or subsystems. The design stage takes as its initial input the requirements identified in the approved requirements document. For each requirement, a set of one or more design elements will be produced as a result of interviews, workshops, and/or prototype efforts. Design elements describe the desired system features in detail, and generally include functional hierarchy diagrams, screen layout diagrams, tables of business rules, business process diagrams, pseudo- code, and a complete entity- relationship diagram with a full data dictionary. These design elements are intended to describe the system in sufficient detail, such that skilled developers and engineers may develop and deliver the system with minimal additional input design. Environments. Each environment is aligned with different areas of the SDLC and is intended to have specific purposes. Examples of such environments include the: Development environment, where developers can work independently of each other before trying to merge their work with the work of others,Common build environment, where merged work can be built, together, as a combined system,Systems integration testing environment, where basic testing of a system's integration points to other upstream or downstream systems can be tested,User acceptance testing environment, where business stakeholders can test against their original business requirements,Production environment, where systems finally get deployed to, for final use by their intended end users. Testing. Unit, system and user acceptance testings are often performed. This is a grey area as many different opinions exist as to what the stages of testing are and how much, if any iteration occurs. Iteration is not generally part of the waterfall model, but the means to rectify defects and validate fixes prior to deployment is incorporated into this phase. The following are types of testing that may be relevant, depending on the type of system under development: Training and transition. Maintaining the system is an important aspect of SDLC. As key personnel change positions in the organization, new changes will be implemented. There are two approaches to system development; there is the traditional approach (structured) and object oriented. Information Engineering includes the traditional system approach, which is also called the structured analysis and design technique. The object oriented approach views the information system as a collection of objects that are integrated with each other to make a full and complete information system. Evaluation. System analysis and design can be considered the meta- development activity, which serves to set the stage and bound the problem. SAD can be leveraged to set the correct balance among competing high- level requirements in the functional and non- functional analysis domains. System analysis and design interacts strongly with distributed enterprise architecture, enterprise I. T. Architecture, and business architecture, and relies heavily on concepts such as partitioning, interfaces, personae and roles, and deployment/operational modeling to arrive at a high- level system description. This high level description is then further broken down into the components and modules which can be analyzed, designed, and constructed separately and integrated to accomplish the business goal.
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