5 stages of software development process Requirements analysis and definition: Establish the application’s goals and constraints in consultation with users Design: Establish the system’s architecture Implementation and unit testing: Realize the design as a set of programs or program units Unit testing verifies that each unit meets its specification Integration and system testing: Integrate the program units and test as a complete system Maintenance: Correct errors, improve implementation, and enhance the system’s services as new requirements are discovered
What is the primary driver of software costs? Most money and effort (82%) spent in testing and maintenance But: 85% of errors are introduced during requirements analysis and design 3% 8% 7% 15% 67% Requirements -- 3% Design -- 8% Implementation -- 7% Testing -- 15% Maintenance -- 67% Software Cost
A sequential software development model (a process for the creation of software) in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing (validation), integration, and maintenance. Waterfall model of software process
Waterfall model Progress flows from the top to the bottom, like a waterfall.
An extension of the waterfall model. Instead of moving down in a linear way, the process steps are bent upwards after the coding phase, to form the typical V shape. The V-Model demonstrates the relationships between each phase of the development life cycle and its associated phase of testing. V model of software process
Prototyping of software process This model adds prototyping as sub-process This model A prototype is a partially developed product that enables customers and developers to examine some aspect of a proposed system and decide if it is suitable for a finished product Why add prototypes to the life cycle? Used to explore the risky aspects of the system: Risk of developing the “wrong” system (what customer doesn’t want), can be a user interface without functionalityuser interface Other technical risks – e.g. performance, using a new technology, alternative algorithms, etc. Prototype may be thrown away or evolve into product
Rational Unified Process (RUP) Developed by “three amigos” at Rational Software (IBM) Grady Booch, Ivar Jacobson, and Jim Rumbaugh Unified Modeling Language (UML) is a set of graphical and linguistic notations for modeling systems, not a process or method The three amigos also developed Rational Unified Process (RUP) You don’t have to use RUP to use UML Interestingly different from the traditional waterfall model Highly iterative and incremental process Software product is not released in one big bang at end of project Instead, developed and released in pieces (prototypes, partial releases, beta, etc.)
How do traditional stages iterate? Workflows look traditional, but they iterate in four phases
What does iteration imply about RUP? How can iterations reduce risk or reveal problems?
14 UML stands for Unified Modeling Language In the field of software engineering, UML is a standardized specification language for object modeling. UML is a general-purpose modeling language that includes a graphical notation used to create an abstract model of a system, referred to as a UML model. What is UML?
16 What is UML? Is a language. It is not simply a notation for drawing diagrams, but a complete language for capturing knowledge(semantics) about a subject and expressing knowledge(syntax) regarding the subject for the purpose of communication. Applies to modeling and systems. Modeling involves a focus on understanding a subject (system) and capturing and being able to communicated in this knowledge. It is the result of unifying the information systems and technology industry’s best engineering practices (principals, techniques, methods and tools).
Unified Modeling Language (UML) 17 used for both database and software modeling version 1.1 was adopted in November 1997 by the Object Management Group (OMG) as a standard language for object-oriented analysis and design Initially based on a combination of the Booch, OMT (Object Modeling Technique) and OOSE (Object-Oriented Software Engineering) methods, UML was refined and extended by a consortium of several companies, and is undergoing minor revisions by the OMG Revision Task Force. Ivar Jacobson is known as the father of Use Cases.
18 1.Structural Modeling with UML Structural model: a view of an system that emphasizes the structure of the objects, including their classes, relationships, attributes and operations. 2.Use Case Modeling with UML Use case model: a view of a system that emphasizes the behavior as it appears to outside users. A use case model partitions system functionality into transactions (‘use cases’) that are meaningful to users (‘actors’). Topics on UML
2.1 Structural Modeling 19 What is structural modeling? Core elements Core relationships Structural diagram
What is structural modeling? 20 Structural model: a view of an system that emphasizes the structure of the objects, including their classes, relationships, attributes and operations.
Structural Diagram Tour 25 Show the static structure of the model the entities that exist (e.g., classes, interfaces, components, nodes) internal structure relationship to other entities Do not show temporal information Kinds static structural diagrams class diagram object diagram implementation diagrams component diagram deployment diagram
Static Structural Diagrams 26 Shows a graph of class elements connected by static relationships. kinds class diagram: class view object diagram: instance view
Implementation Diagrams Show aspects of model implementation, including source code structure and run-time implementation structure Kinds component diagram deployment diagram
Shows the organizations and dependencies among software components Components may be specified by classifiers (e.g., implementation classes) implemented by artifacts (e.g., binary, executable, or script files) Component Diagram
Component Diagram Example Order System component depends both on the Customer Repository and Inventory System components
Deployment Diagram Models the physical deployment of artifacts (software components) on nodes (hardware components) Deployment diagrams are used to show which components may run on which nodes
Deployment Diagram Example Deployment Diagram of Order Management System ( a web based application is deployed in a clustered environment using server 1, 2, and 3.)
2.2 Use Case Modeling 44 What is use case modeling? Core elements Core relationships Diagram tour Example: Online HR System
What is use case modeling? 45 use case model: a view of a system that emphasizes the behavior as it appears to outside users. A use case model partitions system functionality into transactions (‘use cases’) that are meaningful to users (‘actors’).
Online HR System: Update Benefits Use Case 53 n Actors : employee, employee account db, healthcare plan system, insurance plan system n Preconditions: o Employee has logged on to the system and selected ‘update benefits’ option n Basic course o System retrieves employee account from employee account db o System asks employee to select medical plan type; include Update Medical Plan o System asks employee to select dental plan type; include Update Dental Plan o … n Alternative courses o If health plan is not available in the employee’s area the employee is informed and asked to select another plan...
Ideas to Take Away 54 UML is effective for modeling large, complex software systems It is simple to learn for most developers, but provides advanced features for expert analysts, designers and architects It can specify systems in an implementation-independent manner Structural modeling specifies a skeleton that can be refined and extended with additional structure and behavior Use case modeling specifies the functional requirements of system in an object-oriented manner