Software: Instructions to the Computer
• A computer program is a series of instructions to a computer to execute any and all processes
• Computers only “understand” instructions consisting of electrical signals alternating between two states
Software: Instructions to the Computer (Cont.)
• Application software enables users to complete a particular task, such as word processing
• System software enables application software to run on a computer and manages the interaction between hardware devices
Programming Languages
• Abbreviated forms of instructions that translate into machine language
• New programming languages make programming easier for people who are not necessarily hardware experts
Application Software vs. System Software
• Application: – Program developed to address a specific
business need; software for development of such programs
• System: – Programs designed to carry out general
routine operations, such as loading, copying, or deleting a file
Programming Languages (Cont.)
Bugs
• Errors in a program to be eliminated before it runs smoothly
• Occur when a certain operation cannot be carried out
• Logic errors are most difficult to spot
Application Software
• Application-specific programs
– Programs designed to perform specific jobs
• General-purpose programs
– Usable for different purposes
System Software
• Manages computer resources and performs routine tasks not specific to any application
– Copying and pasting sections and files
– Printing documents
– Allocating memory
• Developed to partner with application software
Operating Systems (O/S)
• Most important system software
– Developed for a certain microprocessor or microprocessors
– Addresses technical details such as registers and RAM addresses
– Plays the role of “traffic cop” or the “boss” of computer resources
Operating Systems (O/S) (Cont.)
System Software
Operating System Functions
• Systems Management
• User Interface
• Memory Allocation
• Multitasking, Multiprogramming, and Multiprocessing
• Times and Statistics
• Increasing Services from O/Ss
Popular Operating Systems
Linux and the Open Source Revolution
• Proprietary software: source code of the software public
• Open source software: source code can be obtained free of charge
• Contains fewer bugs because thousands of independent programmers review the code
Required Reading:
Chapter 1 and 2 from “Understanding Open Source Software Development” by Joseph Feller and Brian Fitzgerald
Boole Q+1 005.1 Fell
What is Open Source Software?
• The term open source in common usage refers to any software with publicly available source code.
• Open source software is required to have its source code freely available; end-users have the right to modify and redistribute the software, as well as the right to package and sell the software
• Software with source code in the public domain meets the criteria, as does any software distributed under the popular GNU (GPL). Open-Source licences may have additional restrictions, such as a requirement to preserve the author’s names and copyright statement in the code.
What is Open Source Software?
• Open Source can be either systems software (Linux) or application software (Mozilla, OpenOffice)
• Growing in popularity– Linux now has 23% market share– Second only to Microsoft
Open Source Vs Proprietary
• The “source” in “open source” refers to the program code or instructions on which software is based.
• This is freely available for inspection unlike proprietary software e.g. MS Windows which is compiled into an executable form which runs on a computer.
• Once the source is freely available, the software becomes free to the end user, since anyone can install it, compile it and then use it.
Open Source Organisation
• the basic idea behind open source is very simple– When programmers can read, redistribute, and modify the
source code for a piece of software, the software evolves. – People improve it, people adapt it, people fix bugs.– And this can happen at a speed that, if one is used to the
slowpace of conventional software development, seems astonishing.
• The open source community believes that this rapid evolutionary process produces better software than the traditional closed model, in which only a few programmers can see the source and everybody else must blindly use an opaque bloc of bits
Linux
• Developed by Linus Torvalds• Posted code on the internet and invited
other developers to improve it.• Tens of thousands of developers have
worked on it (Open Source Community).• Has been adopted by end-users and by
established hardware vendors such as IBM and HP which supply it as an option with their computers.
Open Source Projects
• Collaborative developments between software writers
• Worldwide workforce of enthusiasts
• Surprisingly, the software developed is stable enough to be used by commercial organisations
Case: OSS in Munich• May 2003 - the city of Munich decided to oust Microsoft
Windows from the 14,000 computers used by local-government employees in favour of Linux, an open-source operating system.
• Although the contract was worth a modest $35m, Microsoft's chief executive, Steve Ballmer, interrupted his holiday in Switzerland to visit Munich and lobby the mayor.
• Microsoft even dropped its prices to match Linux– a remarkable feat since Linux is essentially free and users
merely purchase support services alongside it. • Microsoft still lost
– The city did not wish to place the functioning of government in the hands of a commercial vendor with proprietary standards which is accountable to shareholders rather than to citizens.
http://www.economist.com/business/displayStory.cfm?story_id=2054746
Case: OSS in Munich
• Modern governments generate a vast number of digital files.– From birth certificates and tax returns to criminal DNA records,
the documents must be retrievable in perpetuity.
• So governments are reluctant to store official records in the proprietary formats of commercial-software vendors. This concern will only increase as e-government services, such as filing a tax return or applying for a driving licence online, gain momentum.
• In Microsoft's case, security flaws in its software, such as those exploited by the recent Blaster and SoBig viruses, are also a cause of increasing concern.
Case: OSS in Munich
• Government purchases of software totalled almost $17 billion globally in 2002, and the figure is expected to grow by about 9% a year for the next five years.
• Microsoft controls a relatively small part of this market, with sales to governments estimated at around $2.8 billion.
• It is a crucial market, because when a government opts for a particular technology, the citizens and businesses that deal with it often have to fall into line. (In one notable example, America's defence department adopted the internet protocol as its networking standard, forcing contractors to use it, which in turn created a large market for internet-compliant products.)
Case: Ernie Ball
• Guitar String manufacturer
• In 2000, the Business Software Alliance conducted a raid and audit on the firm – Found a few dozen unlicensed copies of
programs– Settled for $65K + $35k in legal fees– BSA “named and shamed” the firm on the
evening news and newspaper ads
Case: Ernie Ball
• Ball told his IT department he wanted Microsoft products out of his business within six months– “I don't care if we have to buy 10,000 abacuses. We
won't do business with someone who treats us poorly."
• Ball's IT crew settled on open-source software– Red Hat's version of Linux– the OpenOffice office suite– Mozilla's Web browser– plus a few proprietary applications that couldn't be
duplicated by open source.Interview available at
http://news.com.com/2008-1082_3-5065859.html?tag=lh
Advantages: Proprietary Software
• Indemnification;• Maintenance and support;• Licensee doesn’t have to have open source
savvy staff; • Licensees’ rights if:
– media is defective; – software contains viruses, backdoors, etc.;– product fails to meet written technical/business
specifications.
Disadvantages: Proprietary Software
• COST!– License fee– Product bundling—example: Microsoft office.
• Licensee cannot modify or enhance the code;• Often not built to open standards, leading to
interoperability problems;• Shut off from continuing development and
information sharing in open source community;• Some proprietary code is not as good as its
open source counterparts.
Advantages of Open Source
• Effectively free to purchase (but cost of migration from existing systems may be high)
• Lower cost of maintenance since software upgrades are free
• Increased flexibility
Arguments against Open Source
• Has less functionality than commercial software (but commercial software has a lot of functionality that is not used by end-users e.g. Office Assistant)
• More likely to contain bugs since it is not tested commercially– Evidence suggests this is not the case
• Poor quality of support– Although IBM, RedHat etc. do support Linux for a fee
