Chapter 17 Current Trends in System Development Systems Analysis and Design in a Changing World, 5th Edition

Learning Objectives Explain the foundations for the adaptive development methodologies List and describe the features of the Unified Process system development methodology List and describe the features of Agile Modeling Compare and contrast the features of Extreme Programming and Scrum development Explain the importance of Model-Driven Architecture on enterprise-level development Describe frameworks and components, the process by which they are developed, and their impact on system development

Overview The IS discipline is dynamic and always changing More complex system requirements have necessitated a whole new set of tools The Unified Process (UP)‏ Radical, adaptive approaches, including Agile Development, Extreme Programming, and Scrum Model-Driven Architecture for enterprise-level systems Object frameworks and components to increase productivity and quality

Software Principles and Practices Ubiquitous computing is the current trend in our society Using computer technology in every aspect of our lives The effort to develop current solutions is demanding Current trends in modeling and development processes use five important principles Abstraction Process of extracting core principles from a set of facts or statement Example: Metamodels describe the characteristics of another model Models and modeling An abstraction of something in the real world, representing a particular set of properties

Software Principles and Practices (cont’d)‏ Patterns Standard solutions to a given problem or templates that can be applied to a problem Reuse Building standard solutions and components that can be used over and over again Methodologies A process—including the rules, guidelines, and techniques—that defines how systems are built

Adaptive Approaches to Development Opposite end of spectrum from predictive approaches (recall Chapter 2)‏ Allow for uncertainty Use empirical controls, not predictive controls Describe processes that are variable and unpredictable Monitor progress and make corrections on the fly

Adaptive Approaches to Development— Characteristics Less emphasis on up-front analysis, design, and documentation More focus on incremental development More user involvement in project teams Reduced detailed planning Used for near-term work phases only Tightly control schedules by fitting work into discrete time boxes More use of small work teams that are self-organizing

The Unified Process (UP)‏ Object-oriented system development methodology (system development process)‏ Offered by Rational/IBM, UP developed by Booch, Rumbaugh, and Jacobson UP should be tailored to organizational and project needs Highly iterative life cycle Project will be use-case driven and modeled using UML

The Unified Process Life Cycle UP life cycle Includes four phases which consist of iterations Iterations are “mini-projects” Inception – develop and refine system vision Elaboration – define requirements and design and implement core architecture Construction – continue design and implementation of routine, less risky parts Transition – move the system into operational mode

The Unified Process Life Cycle Figure 17-1

UP Phases and Objectives Figure 17-2

The UP Disciplines UP defines disciplines used within each phase Discipline – set of functionally related development activities Each iteration includes activities from all disciplines Activities in each discipline produce artifacts – models, documents, source code, and executables Learning CIS/MIS means learning techniques from these disciplines Six main UP development disciplines Business modeling, requirements, design, implementation, testing, and deployment Three additional support disciplines Project management, configuration and change management, and environment

The UP Disciplines (cont’d)‏ Six main UP development disciplines Business modeling, requirements, design, implementation, testing, and deployment Three additional support disciplines Project management, configuration and change management, and environment

UP Disciplines Used in Varying Amounts in Each Iteration Figure 17-3

UP Life Cycle Model Showing Phases, Iterations, and Disciplines Figure 17-4

The Agile Development Philosophy and Modeling Agile Development Principles A philosophy and set of guidelines for developing software in an unknown, rapidly changing environment Requires agility – being able to change direction rapidly, even in the middle of a project Agile Modeling Principles A philosophy about how to build models, some of which are formal and detailed and others are sketchy and minimal

Adaptive Methodologies Using Agile Modeling Figure 17-5

The Agile Development Philosophy and Values Responding to change over following a plan An agile project is chaordic – both chaotic and ordered Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation

Agile Modeling Principles AM is about doing the right kind of modeling at the right level of detail for the right purposes Use models as a means to an end instead of building models as end deliverables Does not dictate which models to build or how formal to make those models Has basic principles to express the attitude that developers should have as they develop software

Agile Modeling Principles Figure 17-6

Agile Modeling Practices Figure 17-7

Extreme Programming (XP)‏ An adaptive, agile development methodology created in the mid-1990s Takes proven industry best practices and focuses on them intensely Combines those best practices (in their intense form) in a new way to produce a result that is greater than the sum of the parts

XP Core Values Communication Simplicity Feedback Courage In open, frequent verbal discussions Simplicity In designing and implementing solutions Feedback On functionality, requirements, designs, and code Courage In facing choices such as throwing away bad code or standing up to a too-tight schedule

Some XP Practices Planning Testing Pair programming Simple designs Users develop a set of stories to describe what the system needs to do Testing Tests are written before solutions are implemented Pair programming Two programmers work together on designing, coding, and testing Simple designs “KISS” and design continuously

Some XP Practices (cont’d)‏ Refactoring Improving code without changing what it does Owning the code collectively Anyone can modify any piece of code Continuous integration Small pieces of code are integrated into the system daily or more often System metaphor Guides members towards a vision of the system

Some XP Practices (cont’d)‏ On-site customer Intensive user/customer interaction required Small releases Produce small and frequent releases to user/customer Forty-hour work week Project should be managed to avoid burnout Coding standards Follow coding standards to ensure flexibility

XP Core Values and Practices Figure 17-8

XP Project Activities System-level activities Release-level activities Occur once during each development project Involve creating user stories to planning releases Release-level activities Cycle multiple times – once for each release Are developed and tested in a period of no more than a few weeks or months Iteration-level activities Code and test a specific functional subset in a few days or weeks

XP Development Approach Figure 17-9

Scrum A quick, adaptive, and self-organizing development methodology Named after rugby’s system for getting an out-of-play ball into play Responds to a current situation as rapidly and positively as possible A truly empirical process control approach to developing software

Scrum Philosophy Responsive to a highly changing, dynamic environment Focuses primarily on the team level Team exerts total control over its own organization and work processes Uses a product backlog as the basic control mechanism Prioritized list of user requirements used to choose work to be done during a Scrum project

Scrum Organization Product owner Scrum master Scrum team or teams The client stakeholder for whom a system is being built Maintains the product backlog list Scrum master Person in charge of a Scrum project Scrum team or teams Small group of developers Set their own goals and distribute work among themselves

Scrum Practices Sprint Parts of a sprint The basic work process in Scrum A time-controlled mini-project Firm 30-day time box with a specific goal or deliverable Parts of a sprint Begins with a one-day planning session A short daily Scrum meeting to report progress Ends with a final half-day review

Scrum Software Development Process Figure 17-10

Project Management and Adaptive Methodologies Project time management Smaller scope and focused on each iteration Realistic work schedules Project scope management Users and clients are responsible for the scope Scope control consists of controlling the number of iterations Project cost management More difficult to predict because of unknowns Project communication management Critical because of open verbal communication and collaborative work

Project Management and Adaptive Methodologies (cont’d)‏ Project quality management Continual testing and refactoring must be scheduled Project risk management High-risk aspects addressed in early iterations Project human resource management Teams organize themselves Project procurement management Integrating purchased elements into the overall project Verifying quality of components Satisfying contractual commitments

Model-Driven Architecture Model-Driven Architecture (MDA) is an OMG (Object Management Group) initiative Built on the principles of abstraction, modeling, reuse, and patterns Provides companies with a framework to identify and classify all system development work being done in an enterprise MDA extracts current systems features and information and combines them into a platform independent model (PIM)‏

Model-Driven Architecture (cont’d)‏ Platform-independent model (PIM)‏ Describes system characteristics that are not specific to any deployment diagram Uses UML Platform-specific model (PSM)‏ Describes system characteristics that include deployment platform requirements A set of standard transformations by the OMG move a PSM to a PIM

Software Development and MDA Figure 17-11

Metamodels and Transitions between PIM, PSM, and Code Figure 17-12

Partial Metamodel of UML Class Diagram Figure 17-13

Object Frameworks A set of classes that are designed to be reused in a variety of programs The classes within an object framework are called foundation classes Can be organized into one or more inheritance hierarchies Application-specific classes can be derived from existing foundation classes

Object Framework Types User-interface classes Commonly used objects within a GUI Generic data structure classes Linked lists, binary trees, and so on, and related processing operations Relational database interface classes Classes to create and perform operations on tables Classes specific to an application area For use in a specific industry or application type

Impact on Design and Implementation Frameworks must be chosen early in the project Systems design must conform to specific assumptions about application program structure and operation that the framework imposes Design and development personnel must be trained to use a framework effectively Multiple frameworks might be required, necessitating early compatibility and integration testing

Components Software modules that are fully assembled and ready to use Reusable packages of executable code Have well-defined interfaces to connect them to clients or other components Public interfaces and encapsulated implementation Standardized and interchangeable Updating a single component does not require relinking, recompiling, and redistributing an entire application

Component Standards and Infrastructure Interoperability of components requires standards to be developed and readily available Components might also require standard support infrastructure Software components have more flexibility when they can rely on standard infrastructure services to find other components Networking standards are required for components in different locations

CORBA and COM+ CORBA (Common Object Request Broker Architecture) is a standard for software component connection and interaction developed by the OMG An object request broker (ORB) provides component directory and communication services The Internet Inter-ORB Protocol (IIOP) is used to communicate among objects and ORBs Component Object Model Plus (COM+) is a standard for software component connection and interaction developed by Microsoft

Enterprise JavaBeans Part of the Java programming language’s extensive object framework (JDK)‏ A JavaBean can execute on a server and communicate with clients and other components using CORBA A JavaBean implements the required component methods and follows the required naming conventions of the JavaBean standard Platform independent

Components and the Development Life Cycle Component purchase and reuse is a viable approach to speeding completion of a system Purchased components can form all or part of a newly developed or re-implemented system Components can be designed in-house and deployed in a newly developed or re-implemented system

Using Purchased Components— Implications Standards and support software of purchased components must become part of the technical requirements definition A component’s technical support requirements restrict the options considered during software architectural design

Monitoring System Performance Examine component-based designs to estimate network traffic patterns and demands on computer hardware Examine existing server capacity and network infrastructure to determine their ability to accommodate communication among components Upgrade network and server capacity prior to development and testing Test system performance during development and make any necessary adjustments Continuously monitor system performance after deployment to detect emerging problems Redeploy components, upgrade server capacity, and upgrade network capacity to reflect changing conditions

Services New method of software reuse enabled by Internet— external services identified and used for applications Called Web services and service-oriented architecture (SOA)‏ Microsoft .NET is service standard based on SOAP Java 2 Web Services (J2WS) is service standard for services in Java

Component Communication Using SOAP Figure 17-14

Summary Adaptive development methodologies Unified Process (UP)‏ Agile Modeling and Agile Development Flexibility in an unpredictable business world Extreme Programming (XP)‏ Tests are written first; programmers work in pairs Scrum Defines a specific goal that can be completed within four weeks