Information Systems Analysis and Design CSC340 XVI System Design What is System Design The Outputs of System Design The Global System Architecture Classification of Applications State of the Market 2003 Jaelson Castro and John Mylopoulos System Design 1 Information Systems Analysis and Design CSC340 The Information System Lifecycle Again Survey project scope feasibility feasibility study Study current system problem statement Define end user reqs initial requirements project request Select feasible solution System Design delivered system Design new system Maintain improve system new system 2003 Jaelson Castro and John Mylopoulos detailed requirements configuration Select Acquire new S H W design spec Deliver new system S W Construct new system System Design 2 Information Systems Analysis and Design CSC340 Major Concerns of System Design Identify major subsystems and components Identify usage control or data dependencies among subsystems Decide on a hardware and software platform for the new system I e the hardware and network s on which it will run the operating system and other off the shelf software e g DBMSs it will use Allocate subsystems to hardware nodes for a possibly distributed system Decide on a data management strategy Choose a strategy and standards for human computer interfaces 2003 Jaelson Castro and John Mylopoulos System Design 3 Information Systems Analysis and Design CSC340 Other Elements of System Design Not discussed in this course Plan control aspects of the application Produce test plans Specify code development standards Set priorities for design trade offs Identify implementation requirements e g data conversion 2003 Jaelson Castro and John Mylopoulos System Design 4 Information Systems Analysis and Design CSC340 Outputs of the Design Phase Hardware networking and software platform for the new system A global system architecture which describes the hardware nodes and communication connections among them A software architecture for the new system showing the hierarchy of subsystems and their inter dependencies An allocation of subsystems and data to hardware nodes A detailed description of interactions between different elements of the design through sequence collaboration state and activity diagrams A database design consisting of a database schema for the data managed by the new system User interfaces for different groups of users 2003 Jaelson Castro and John Mylopoulos System Design 5 Information Systems Analysis and Design CSC340 Global System Architecture Describes the collection of inter connected hardware nodes on which the system will eventually run A global system architecture consists of Hardware nodes where components of the new system will run for each node select a hardware configuration and operating system platform that will run for example hardware platform 486 2MB RAM 100MB disk OS DOS Windows The connectivity among hardware nodes defined by length of connection type of connection product used for the connection for example length 100ft 100miles type twisted pair fiber optic ethernet product Novell 386 LAN PC3270 The location of users inputs and outputs for the new system Key concern Minimize data data communication communication 2003 Jaelson Castro and John Mylopoulos System Design 6 Information Systems Analysis and Design CSC340 Example To each hardware node associate users external entities and network interconnections 486 DOS Win 100MB disk 100ft Twisted pair PC3270 200ft Ethernet Novell 386 LAN 486 DOS Win 100MB disk Accounts Receivable Accounts Payable OS 400 5 ter 5GB disk 100mi modem 28800 PC3270 IBM 3090 MVS 25 terminals 386 notepads DOS 80MB disk Business Administrator 1 500ft Twisted pair SNA 100ft Token ring Novell386 486 DB server 1mi fiber opt DOS 2GBdisk TCP IP 486 DOS Win 100MB disk Financial Managers VP Finance Purchasing Department 2003 Jaelson Castro and John Mylopoulos System Design 7 Information Systems Analysis and Design CSC340 Distribution Issues Batch mode process a batch of inputs outputs together sometimes most appropriate solution e g incoming mail purchase orders outgoing mail invoices cheques On line mode process inputs outputs as they become available can save data entry time particularly if end user can do the input clearly the way of the future because on line data entry can be done on PCs Remote batch data are input on line on several machines then fed in a batch mode to a centralized database 2003 Jaelson Castro and John Mylopoulos System Design 8 Information Systems Analysis and Design CSC340 New Technologies for I O and New Standards for Data Interchange Keyless data entry bar coding optical character recognition special keyboards very appropriate for large volumes of I O Pen input several products in the market with mixed success rate for different types of data Electronic data interchange EDI data are transferred through telephone lines from one location to another e g credit card charging Image and Document Interchange like electronic data interchange but now whole documents including images are passed around e g law enforcement bank applications HTML XML SGML markup languages for documents SGML is a general markup languages for documents HTML is a special version used for WWW documents XML is something in between 2003 Jaelson Castro and John Mylopoulos System Design 9 Information Systems Analysis and Design CSC340 Choosing a System Architecture Here is a series of issues that need to be addressed Establish batch and on line computer processes key consideration data communication and response time e g on site conference registration Determine process cycles i e when does each process need to run e g end of month end of project Establish processing locations identify user locations and numbers processor locations types and numbers storage devices and storage capacities connection protocols and traffic volumes Distribute data to locations simple solution all in one location more and more we are moving towards distributed DB solutions Distribute software subsystems to locations Assign technology what hardware software is going to run where 2003 Jaelson Castro and John Mylopoulos System Design 10 Information Systems Analysis and Design CSC340 Classification of Applications Operational Support Span Type Decision Support Real Time browsing analysis E g video conferencing within group Group Dept E g regional inventory control E g regional marketing info system Enterprise E g enterprisewide cash mgt E g
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