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Systems Analysis & Programming Page 491

10.1 Systems Development Purpose of a System A System is a collection of related components that interact to perform a task in order to accomplish a goal A computer-based system consists of hardware, software, people, procedures, and data, as well as communications setups Page 492 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development How It Starts, Who’s Involved Users: The new system must ALWAYS be developed in consultation with the people who will be using the completed system Management: Managers within an organization should be consulted about the system, because they control the budget and resources Technical staff: The Information Systems or IT staff must be involved, because they will have to execute the project or work with the people who do Systems Analyst: Information specialist who performs systems analysis, design, and implementation Page 493 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Six Phases of Systems Analysis and Design Systems analysis and design is a six-phase problem-solving procedure for examining an information systems and improving it The systems development life cycle (SDLC) is the particular step-by-step process followed during systems analysis and design © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Systems Development Life Cycle (Six Phases): Preliminary investigation Systems analysis Systems design Systems development Systems implementation Systems maintenance Information systems are frequently revised and upgraded Steps in the cycle often overlap Page 493 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 1: Conduct a Preliminary Investigation Conduct a preliminary analysis Propose alternative solutions Interview people within the organization Study what competitors are doing Decide to leave the system as is, improve it, or develop a new system Describe costs and benefits Submit a preliminary plan with recommendations This should be a written report Get management approvals for next phase Page 494 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 2: Analyze the System Gather data Interview employees and managers Develop, distribute, analyze questionnaires Review current written documents Observe people and processes at work Analyze the data Use modeling tools, such as CASE tools Create a data flow diagram to show how data flows through the system Pages 494-495 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 2: Analyze the System (continued) Write a report Document how the current system works Document problems with the current system Describe the requirements for the new system Recommend what to do next Get management approval to proceed © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 3: Design the System Do a preliminary design Often involves prototyping and continued use of CASE tools Do a detail design, showing: Output requirements Input requirements Storage requirements Processing requirements System controls Backup Write a report and get approval for next phase Pages 496-497 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 4: Develop the System Develop or acquire the software Make-or-buy decision If creating own system, programming (coding must be done) Acquire or upgrade the hardware Test the system Unit testing: performance of system’s individual parts tested System testing: parts are linked and tested to see if they work together properly; real data may be used Pages 497-498 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 5: Implement the System Choose a strategy to convert to the new system Direct implementation: quit the old and start using the new Parallel implementation: use both the old and the new side by side, until the new system has been proved reliable Phased implementation: phase in parts of new in gradually as parts of old are phased out Pilot implementation: have the new system tried out by a few users Train the users Pages 498-499 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.1 Systems Development Phase 6: Maintain the System Perform system audits and periodic evaluations Make changes to the system based on new conditions Finalize documentation Note that documentation should have been continuously maintained during the entire SDLC Page 499 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure A program is a list of instructions that the computer must follow to process data into information Programming is done during phase 4 of the SDLC The five steps: Clarify/define the problem Design the program Code the program Test the program Document and maintain the program Pages 499-500 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Step 1: Clarify the Programming Needs Clarify objectives & users Clarify desired outputs Clarify desired inputs Clarify the desired processing Double-check the feasibility of implementing the program Document the analysis Pages 500-501 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Step 2: Design the Program Create an algorithm, or set of clear steps, to solve the problem Use structured programming approach Determine program logic using top-down approach and modules, using a hierarchy chart (graphic form) and pseudocode (narrative form) Pages 501-502 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Pseudocode Page 503 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Page 505 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Step 2: Design the Program (continued) Structured programming Use control structures: Sequence: one statement follows another in logical order Selection: IF-THEN-ELSE Iteration (loop): DO UNTIL / DO WHILE © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Page 506 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Step 3: Code the Program Translate the logic requirement from flowcharts and pseudocode into a programming language Select a programming language--set of rules that tells the computer what operations to do Each programming language has a syntax, or set of grammatical rules to follow to write valid expressions Syntax rules must be followed or there will be syntax errors Computers don’t understand what you want, only what you type in Pages 507-508 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Step 4: Test the Program Desk checking is reading through, or checking, the program for syntax errors and logic errors Debugging is the process of detecting, locating, and removing all syntax errors and logic errors in a computer program Beta testing is the process of testing the program using real data One phase of testing uses correct data Once the program works, the next phase of testing uses invalid data and untrained users to root out hidden errors Page 508 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.2 Programming: A Five-Step Procedure Step 5: Document and Maintain the Program Documentation is written descriptions of what a program is and how to fix it; should be done through all 5 steps User documentation – for the people who will use the program (e.g., user manual – hardcopy or CD, and online) Operator documentation – for the computer operators, so they know what to do if the program or hardware malfunctions Programmer documentation – for the next programmer who must modify and maintain what has been written Maintain the program – keep everything in working condition Pages 509-510 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.3 Five Generations of Programming Languages First Generation: Machine Language The basic language of the computer – all 0s and 1s Each CPU model has its own machine language, thus machine language is machine dependent Not convenient for people to read and use Evolution of languages started in 1945 Pages 511-512 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.3 Five Generations of Programming Languages Second Generation: Assembly Language Low-level mnemonic version of machine language; uses abbreviations and simple words Faster to program in than machine language Is also machine dependent Assembler program needed to translate assembly language into machine language Pages 512-513 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.3 Five Generations of Programming Languages Third Generation: High-level Languages (Procedural Languages) These languages resemble human language (e.g., English) and are portable (not machine dependent) Examples are FORTRAN, COBOL, BASIC, Pascal, C The programmer writes the source code, then uses a translator program to interpret or compile the code into machine language (object code) Interpreter translates and executes immediately Compiler translates and saves the code as an entire unit to be executed later Pages 513-514 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.3 Five Generations of Programming Languages Fourth Generation: Very-High-Level or Problem-Oriented Languages Easier to program in than third-generation languages Three types: Report generators (RPGIII) Query languages (SQL) Application generators (NOMAD, FOCUS)—used to create parts for other programs Pages 514-515 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.3 Five Generations of Programming Languages Fifth Generation: Natural Languages Programming languages that use human language to give people a more natural connection with computers Part of the field of artificial intelligence (AI; Chapter 8) Page 516 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.4 Programming Languages Used Today FORTAN The language of mathematics The first high-level language written A machine-independent procedural language COBOL The most-frequently used language for business legacy applications on mainframe computers Pages 516-517 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.4 Programming Languages Used Today BASIC Designed to be an easy language to use and learn programming with Usually run from an interpreter, but can be compiled Procedural language Supplanted by Microsoft’s Visual Basic for commercial/business use Pascal Designed to be a language to teach programming Structured, compiled language Not used in business or commercial companies Pages 518-519 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.4 Programming Languages Used Today C General-purpose machine-independent compiled language developed for mid-range computers Used to write the Unix operating system Widely used for writing common software applications and is necessary for programmers to know Doesn’t handle math as well as FORTRAN Page 519 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.4 Programming Languages Used Today LISP: For Artificial Intelligence Programs Third-generation language Used to control AI programs Used to write expert systems and natural language programs Page 519 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.5 Object-Oriented & Visual Programming In object-oriented programming (OOP), data and processing instructions are combined into a self-sufficient object that can be reused Object Self-contained module consisting of reusable code Message The instruction received by the object indicating it is time to perform an action Method The processing instructions within the object to perform the specified action Pages 519-520 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.5 Object-Oriented & Visual Programming Three basic concepts of OOP Encapsulation One object contains (encapsulates) both data and relevant processing instructions Inheritance One object can be used as the foundation for other objects Objects can be arranged in hierarchies – classes and subclasses Objects can inherit actions and attributes from one another Polymorphism Allows a single definition to be used with different data types and different functions Means a message produces different results depending on the object it is sent to Pages 520-521 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.5 Object-Oriented & Visual Programming Examples of OOP languages C++ Object-oriented language that was developed after C Often used to write computer games and CPU- and graphics-intensive applications Java Developed at Sun Microsystems in early 1990s Derivative of C++ with simpler memory management and syntax Used to develop Java applets to be downloaded into web browsers to make websites interactive and more attractive (e.g., with animations) Page 521 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.5 Object-Oriented & Visual Programming Visual programming is a method of creating programs in which the programmer makes connections by clicking on objects, diagrams, and icons and by interacting with flowcharts Using a mouse, the programmer drags and drops objects on screen This makes it fast and easy to build prototype user interfaces and get end-user approval before doing a lot of programming Visual BASIC is an example of visual programming Pages 521-522 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages A markup language is a kind of coding (“tags”) inserted into text that embeds details about the structure and appearance of the text HTML is a markup language (internet use) Has codes for indicating layout and styling (such as boldface, italics, paragraphs, insertion of graphics, etc.) SGML: improved markup language Specifies a syntax for including the markup in documents Allows users to create and use any markup they wish Script: short list of self-executing commands embedded in a web page that perform a specified function or routine Pages 522-523 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages HTML Hypertext markup language Used to create 2-D web pages Also lets you insert hypertext links in web pages VRML Virtual Reality Modeling (Markup) Language is used to create 3-D web pages, including interactive animation Requires special VRML browser to view VRML pages Used by web designers, along with HTML Page 523 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages XML eXtensible Markup Language is a metalanguage written in SGML that allows one to facilitate easy document interchange on the internet XML lets you create your own tags (“extensible”) XML statements define data content JavaScript Not the same language as Java An object-oriented scripting language that adds interactive functions to HTML web pages Pages 523-524 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages ActiveX Developed by Microsoft as an alternative to Java for creating interactive web pages A set of controls or components that enable programs or content of almost any type to be embedded in a web page; comprises reusable components that can be plugged into other applications ActiveX controls are written in C, C++, Visual BASIC, and Java Often used by crackers to propagate viruses and/or Trojans; before you allow an ActiveX component to download from your browser to your computer, make sure you trust that website Page 525 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages Perl A general-purpose programming language developed for text manipulation. Used for web development, network programming, system administration, GUI development, other tasks Widely used for web server programs to perform automatic tasks such as updating user accounts and newsgroup postings Page 525 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages CGI (Common Gateway Interface) Standard protocol for interfacing external application software with a web server Manages the exchange of information and makes web pages more interactive TCL (Tool Command Language) Created for the Unix platform Interpreted script language Comparable to JavaScript and Visual BASIC Page 525 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.

10.6 Markup & Scripting Languages Ruby Basic and completely object-oriented scripting language Open-source language Can be compiled and run on most operating systems PHP (Personal Home Page, or PHP Hypertext Preprocessor) and R Allows creation of dynamic content that interacts with databases Normally found on Linux servers with MySQL databases General-purpose scripting language R used in data mining Pages 525-526 © 2011 The McGraw-Hill Companies, Inc. All rights reserved.