System Analysis and Design

1. System Analysis and Design By: Jason Poli (Group Manager), Eric Wolk, Mathew Teller, Jeremy Cullen, Eduardo Lebron

2. The Software Development Life Cycle • develops a plan for creating a new system • a list of tasks or phases in the system’s development • also known as the System Development Life Cycle

3. Software Development Life Cycle

4. The System Analysis • only done when a new system is needed • 3rd step in Software Development Life Cycle, done after the system study and feasibility study • begins with an in depth study of current system and then leads up to what will be needed in the new system to make it better • indicates what the accomplishments are based on the user’s needs • explains the new functions of the system and there relationship to one another

5. Skills of a System Analyst • must know how to speak the language • must have good communication skills • must be creative and have good problem solving skills • must have the ability to work with co-workers • good programming skills

6. System Design • Most vital part when building a new system • There are two stages when designing a system • The general design and detailed design • General Design • The predicted capabilities of the new system are specified • Costs and benefits of building the new system are calculated

7. System Design (Cont.) • Detailed Design • Only done if the general design is possible and practical • More structured type of design • Blueprints of solutions to the given problems of old system • The language in which the program will be written is decided • The plan for the input, output, and processing are drawn up

8. Software Development • Software life cycle models describe phases of the software cycle and the order in which the steps are executed

9. Software Development Cont. • Requirement – the stage in which the problem is identified and research is gathered. • Interviews conducted • Meetings with managers and stake holders • Design – The software design is produced to solve the problem • Implementation – Where the software is coded and created • The main phase for developers • Testing – The product is tested to see if it accurately solves the Problem

10. Advantages and Disadvantages • Advantages: • Easy to manage • Phases are processed and completed one at a time. • Disadvantages: • Adjusting phases during cycle can kill the project • There is a high amount of risk and uncertainty as to how • the project will turn out.

11. Projects • Projects are short term efforts to create a unique product • All projects constrained by three factors • Time • Cost • Scope • These factors are called The Triple Constraints of Project • Project Management • In order for a project to be successful these three factors . must be in balance.

12. Project Planning Phase • The project management life cycle has four phases: • Project Initiation • Project Planning • Project Execution • Project Closing

13. Approaches to System Development • Object-Oriented Approach to System Design • Breaks the system down into different objects, which are made up of data and processes that are carried out using that data.

14. Structured Approach to System Design • Breaks down the system into data which is used by each individual process to carry out a specific task. • In the object-oriented approach, the data and processes were not visible because they were what made up each object. • With the Structured Approach it is the other way around.

15. Structured Approach to System Development Requirements Techniques – Logical Data Modeling Identify, display, and report the data requirements of the system(s) being designed Data Flow Modeling Identify, display, and report the process of how data travels around an information system Entity Behavior Modeling Entity – Technical word for unit or body Identify, display, and report the order of events that have an effect on other entities

16. Stages of Structured Approach • Stages – • Analysis of the current system or situation • Outline business specification • BSO – Business Systems Option • Detailed business specification – prepare to create model with generally accepted BSOs • Logical data design – choose BSO that will be base of development • Logical process design – reasonable designs are further revised • Physical design – identify actual data and design that will be used to create model

17. Data Flow Diagram (DBD) Used to show the way in which data travels throughout the system and connections between the system and any outside units that may have an effect on the system model

18. Data Flow Diagrams cont. • 2 approaches for creation • Top Down Approach – • Show the data flow between the system and the system environment • Break down the system into individual parts or components • Further break down these components to ensure complete detail • Once the most acceptable level of detail is reached the diagram can be created • Event Partitioning Approach • List of events is made • Data flow process is created for each event listed • Link the directly related processes together to show any response to related event • Show reaction of each process

19. Data Flow Diagrams cont. • Components of a DBD • External Entities – source and destination of data flow input and output • Data Storages – units in the system in which data is kept • Functional Transform – represent actions in use on the data • Control Transform – takes in and dishes out signs that can help explain control over data flowing through the system • Notes – used only to add any description of any objects on the diagram that may be unclear • Data Flows – represent movement of data throughout the system

20. Object-Oriented Approach to Requirements • Class and Use Case diagrams Provide common architectural framework for object-oriented programming • These are not the only diagrams that we encounter there is also Systems sequence diagrams (SSDs), State diagrams, and Activity diagrams that help organize objects.

21. Object-Oriented Approach Models • Class diagram – is a definition of the system components • Use case diagrams -- shows the users role in a system and also how they are used in that system • Systems sequence diagrams (SSDs) – this defines all input and output interactions between user and system for a use case diagrams It also shows the order in which it is carried out • State diagrams – shows us all the different ways that modes("state") go through. It also shows what event causes it to a state transition • Activity diagrams – object-oriented equivalent of data flow diagrams (DFDs) from structured approach.

22. Traditional Approach and Object-Oriented Approach

23. Work Cited • John W. Satzinger, Robert B. Jackson, Stephen D. Burd, Richard Johnson. Systems Analysis and Design in a Changing World. 3rd ed., Boston, MA: Course Technology, 2004 • Agile Models Distilled: Potential Artifacts for Agile Modeling. Scott W. Ambler. 2003. Ambysoft Inc. 4 Oct. 2008. <http://www.agilemodeling.com/artifacts/> • www.nos.org/htm/sad1.htm • Wayne P. Stevens, Glenford J. Myers, Larry L. Constantine: Structured Design. IBM Systems Journal 38(2/3): 231-256 (1999) • Interview with Mr. Jeff Stone, IST Professional at St. Lukes Hospital • http://slac.stanford.edu/BFROOT/www/doc/workbook_kiwi/coding/OOvsSASD.html