Software Technology Points z Compile process z Application

Software Technology

Points z. Compile process z. Application Systems z. System software y. Operating system/network access y. Utilities y. User interface environments y. Languages & development tools (CASE) y. Databases

Software Classification APPLICATION DEVELOPMENT SYSTEM

Primacy of Software, not hardware, determines the actions of a computer. Source Code: program code intended to be written or read by people Machine Code: programs in binary form using the computer instruction set

How Software Works: Step 1

How Software Works: Step 2

How Software Works: Step 3

How Software Works: Step 4

Computer Languages z. Language Translation Method yinterpreter ycompiler z. Level of Abstraction ysecond-generation ythird-generation yfourth-generation z. Procedural Versus Nonprocedural z. Command/Data or Object-Oriented

Generations First - Machine language Second - Assembly language Third - High-level languages (COBOL, FORTRAN, BASIC, C, C++, Java, Ada) Fourth - 4 GL (Focus, RAMIS, SQL) Fifth - Natural languages

System Software z. Operating System yprovide an easier user interface ymanage system resources ysupport multiple tasks and multiple users z. Systems Utilities

Types of Interfaces z. Command- oriented interfaces yprompt the user to type in a command that is translated into an instruction for the program to follow z. Menu- driven interfaces yoffer a list of choices or options, called a menu, as a way of letting a user choose from several different commands or functions

Types of Interfaces z. Natural Language interfaces yallow the user to input simple English statements that are translated into commands by the program. z. Graphical User Interfaces (GUI’s)

Operating System Functions z. Booting z. Housekeeping Tasks (formatting, coordinating) z. Managing Computer Resources (memory and devices) z. Managing Files (i. e. , copy, erase) z. Managing Tasks

OS Components APPLICATION PROGRAMS SYSTEM PROGRAMS (COMPILERS, etc. ) MEMORY OPERATING SYSTEM MACHINE LANGUAGE KERNEL MICROPROGRAMMING ROM PHYSICAL EXECUTION CPU

Types of Tasks z. Multitasking y 2 or more programs yuser concurrently on same computer with same CPU z. Multiprogramming y 2 or more programs ymultiuser operating system, shared CPU z. Multiprocessing ymultiple CPUs

Memory Management

Virtual Memory PAGE NUMBER + OFFSET PAGE TABLE FRAME NUMBER + OFFSET PAGE TABLE Pages Page Frames

Addresses z Physical address: actual memory location. NEEDED BY THE CPU z Relative address: offset from a reference physical address. NEEDED BY THE OPERATING SYSTEM z Logical address: address within a programmed unit (e. g. page). NEEDED BY APPLICATION PROGRAMS

Systems Software z. Network Operating Systems ydirecting instructions ycommunicating with the network ysecurity services ydirectory services ydevice management

Workstation Functions REDIRECTION APPLICATION OPERATING SYSTEM CPU NETWORK INTERFACE NIC

Client Functions z. Application execution Fat and thin clients z. Network access Network software and hardware (NIC) z. Application software maintenance z. Remote resources

Client NOS Software Directs requests from the Client to the network

Server Functions z. Shared resources File and print services z. Application management z. Network operating system z. Access to the network Higher layer functions z. Security z. Backup and professional support

Server NOS Software Manages central services and external interfaces • Directory services • Translation protocol

Access z. Centralized y. Legacy applications z. Client/Server y. Scalability y. Ownership y. Management z. Web y. JAVA, etc.

Centralized Model

Client/Server Model z. Two-tier z. Three-tier z. Multitier

Web Model

Mindshare Ownership

Client Focus Bill Gates

Net Focus Larry Ellison

Issue: Desktop Ownership z. Who controls the desktop z. Standardization and version management z. Distribution z. Payment for access

Application Software z. Make or Buy z. Integrated Solutions or Best of Breed z. Preparing for the Year 2000 z. Application Software Life Cycle SDLC Rapid Application Development

Development Environments z. Desktop Systems z. Code Generators z. Development Systems and CASE Tools z. Middleware and other user environments

Integrated Solutions (ERP)

Year 2000 z. Replace Existing Software with Year 2000 Compliant ERP Products z. Repair Legacy Products z. Use Automated Tools z. Build Software that Will Intercept and Convert Dates as They Are Entered, Stored, or Output

Software Acquisition z. Create z. Purchase y. Product y. Contract development z. Lease y. Seat y. Station

1+1=2