INFORMATION SYSTEMS DESIGN

The Systems Development Life Cycle (SDLC)  Systems Planning  Systems Analysis  Systems Design  Systems Implementation  Systems Evolution Planning Evolution Implementation Design Analysis

System Model with its Six Components SYSTEM boundary inputs outputs processing controls feedback Examples: Automobile Student Registration System Others... 3

SYSTEMS DESIGN people procedures data software hardware An AUTOMATED INFORMATION SYSTEM IS An AUTOMATED INFORMATION SYSTEM IS  a type of fabricated system  used by one or more persons  to help people accomplish some task or assignment that they have  utilizes hardware and software

DATA - input, output or already stored electronically DATA - input, output or already stored electronically FUNCTIONS - transformations or actions taken FUNCTIONS - transformations or actions taken BEHAVIOR - the observable effects from interaction BEHAVIOR - the observable effects from interaction SYSTEMS DESIGN DATAFUNCTIONS BEHAVIOR An AUTOMATED INFORMATION SYSTEM has three basic relationships to consider

General Model of Information Systems Development (“Partnership”) Requirements Specification (3) Stakeholder Information Technology Staff Analysis Design and Implementation Requirements (1) Continued Involvement (5) Information System (6) Problem Definition Skills (2) Problem Solution Skills (4)

Systems Analysis and Design Activities and Deliverables ANALYSIS Activities: Systems Planning Feasibility Study (optional) Requirements Determination User Acceptance Prototyping (optional) Deliverables: Requirements Specification Prototype (optional) DESIGN Activities: Deliverable: Physical Design Prototyping (optional) Software Construction/Purchase User Documentation - “Deliverable” Testing Training User Acceptance Conversion Implementing the system Information System Project Management Project Documentation - “Scaffolding” Two on-going activities

In addition: User acceptance, documentation, project management  Planning  Feasibility Study (optional)  Requirements Determination  Conceptual Design  Physical Design  Construction and/or Purchase (prototype)  Training  Conversion - old to new  Implementation  Evolution - maintenance & enhancements SYSTEMS DEVELOPMENT LIFE CYCLE (SDLC) Analysis Design 8

 Economic, Operational & Technical Feasibility  Security Issues  Make (in-house versus outsource) versus Buy  Documentation  Software testing (next slide) SYSTEMS DESIGN ACTIVITIES 1 of 3

INFORMATION SYSTEMS TESTING LAYERS Module Function Sub-system System and Integration User Acceptance Creeping Commitment Alpha & Beta tests 2 of 3

 User-Interface Design (GUI design)  Prototyping  Training  Conversion - cutover and parallel  Implementation - install, activate, institutionalize SYSTEMS DESIGN ACTIVITIES 3 of 3

Verification and Validation*  Verification: The process of evaluating a system or component to determine whether the products of a given phase satisfy the conditions imposed at the start of that phase. (Mainly a paper-based activity that requires you to confirm that each stage of the development conforms to the requirements defined in the previous stage.)  Validation: The process of evaluating a system or component during or at the end of the development process to determine whether it satisfies specified requirements. (Mainly a confirmation that the implemented system/component actually works to specification.) * IEEE Standard Glossary of Software Engineering Terminology, 1994

OBJECT-ORIENTED SYSTEMS DESIGN Problem Domain (PD) Data Management (DM)System Interaction (SI) Information System Model (created during analysis; refined during design) Human Interaction (HI) Good strategy (technique) for developing Client-Server (n-Tier) Systems

Log Information Conduct Business Analyze results Interact with other systems Types of Information System Features (“needed information”) Business Problem Master/Reference Data Business Problem Transaction Data Business Problem Results Business Problem Integration

Student registerForCourse dropCourse requestTranscript payStudentFees etc... studentIDNumber studentName etc... ProblemDomain Human Interaction RegForCourseWin Student services DropCourseWin Student services RequestTranscriptWin Student services PayStudentFeesWin Student services LogonWindow attributes services The HI to PD Relationship

ProblemDomain DataManagementSystemInteraction Information System HumanInteraction Business Problem Devices Other Systems Screens Reports Databases

 Security/Logon Window(s)  Setup Windows - persistent objects  Business Function Windows - supports the human interface for the Problem Domain functionality Human Interaction (HI) OBJECT-ORIENTED SYSTEMS DESIGN

Human Interaction Check-InWindow CustomerWindow EmployeeWindow InventoryWindow LogonWindow PurchaseOrderWindow Sale-RentWindow VendorWindow CustomerStatusReport DailySalesRentReport InventoryStatusReport OverdueRentalItemReport OpenPurchaseOrderReport SaleRentReceiptReport Human Interaction (HI) Video Store Example OBJECT-ORIENTED SYSTEMS DESIGN Compare this list with the Video Store’s PD Component

Human Interaction Check-InWindow CustomerWindow EmployeeWindow InventoryWindow LogonWindow PurchaseOrderWindow Sale-RentWindow VendorWindow CustomerStatusReport DailySalesRentReport InventoryStatusReport OverdueRentalItemReport OpenPurchaseOrderReport SaleRentReceiptReport Check-InWindow attributes services CustomerWindow attributes services EmployeeWindow attributes services InventoryWindow attributes services LogonWindow attributes services PurchaseOrderWindow attributes services.....plus 8 more OBJECT-ORIENTED SYSTEMS DESIGN

 Who “I” Know - connections & constraints  What “I” Know - attributes  What “I” Do - services Human Interaction (HI) OBJECT-ORIENTED SYSTEMS DESIGN

 Stores the problem domain classes with objects that are persistent  Encapsulates search & storage mechanisms for all persistent classes with objects Data Management (DM) OBJECT-ORIENTED SYSTEMS DESIGN

Data Management Problem Domain ConcessionItem Employee Game Inventory Member POLineItem PurchaseOrder RentalItem RentalTransaction SaleItem SaleRentalLineItem SalesTransaction StoreLocation Transaction VCR Vendor Video ConcessionItemDM EmployeeDM GameDM MemberDM POLineItemDM PurchaseOrderDM RentalTransactionDM SaleRentalLineItemDM SalesTransactionDM StoreLocationDM VCRDM VendorDM VideoDM Problem Domain class with objects that need persistence will most often correspond directly with the DM class with objects. Reason: “Plug-and-Play” concept or the “Separation of Concerns” concept OBJECT-ORIENTED SYSTEMS DESIGN

INFORMATION SYSTEMS DESIGN ANALYSIS DESIGN PROGRAMMING DATABASE Structured Object Structured Object Structured Object Conventional, 3rd/4th GL Mix of Conventional/Object Object RDBMS OODBMS RDBMS OODBMS RDBMS OODBMS