Class 5

Computer Software

Outline

System Software

Application Software (“Applications”)

Markup languages for Internet (HTML, XML)

User Interface

Client-Server hardware & software

Managing software acquisition

Software (Computer Program) & Types

Instructions that manage computer hardware.System software

Operating system (MS Windows, Mac OS, Linux)Drivers (connects pieces of hardware & software - !!)

Application software (“Applications”– watch out for language mess!)*

Web browsers, Microsoft OfficeUser interface (screens for users to input data and get output).

Access to data and system’s functionalityShould be easy to use (but!...)

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HTML & XML*

HTML – mark-up language for designing user interface

(screens) on the Web*. Used for controlling look of

screens.

XML - mark-up language used for defining content of

files (e.g., every part a document can be defined)

Useful for transfer of files between different systems on

Internet

Easy to read and format

Weak on security

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User Interface• Both hardware and software concept – all details below belong to User Interface, including the content of the screen (a window displaying the output, clickable icons, images, colours…)

• Today, User Interface is a veryimportant part of an IS, and it should be easy to use.

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Client-Server Model• The model of arranging hardware & software in which one computer serves data storage and processing operations (SERVER) to anothercomputer (CLIENT).

• Server and Client can share storage and processing operations. Ifmost of work done by server, client is “thin” (Thin Client).

• Model can get complex with multiple clients an servers (tiers).

Multi-tear Client-Server Model

Methods of Acquiring Software

1. Build software in house.

Pro: customized to internal needs, technical expertise nurtured

Con: Expensive (staff, development technology, maintenance cost)

2. Outsource development of custom solutions to a software vendor

Pro: Save on staff and development tools

Con: Lock in a vendor – dependence, no own technical expertise,

maintenance cost

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Methods of Acquiring Software

3. Buy off-the-shelf software (one size fits all)

Pro: Cheaper than in-house and outsourcing

Con: No support to specific internal needs (one size may not fit all)

4. Rent

A) Application Service Provider (hosted service)

B) Web Services/Cloud Computing (processing, storage served)

Pro: cheapest, no hardware cost, no maintenance cost, trendy

tech.

Con: dependence, no own technical expertise, privacy & security

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Methods of Acquiring Software

5. Use Open Source software (OS)*

OS = Source code (code of a programming language) is accessible to everybody. Supports some basic functions.

Accessible for free in a basic version and modifiable

Ex. : Linux (operating system), Open Office (like MS Office)

Pro: Affordable, innovative

Con: Support uncertain, no warranty, product life uncertain, requires staff who can understand it and link it with other software as needed.

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Total Cost of Ownership (TCO)

• In managing systems acquisition, don’t consider just capital investment but TCO

• TCO includes capital investment in software and hardware, training, recurring costs for licenses & maintenance, operating costs (salaries, facilities & energy), downtime (opportunity costs), disposing of used equipment…

• Maintenance costs can be large

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Development… Use stage: Discard maintenance, operations, opportunity…