Open Source Software An Introduction

The Creation of Software l As you know, programmers create the software that we use l What you may not understand is HOW software is created

Machine Language l Computer programs (software) are basically sets of instructions that the computer follows l Computers don’t take instructions in English (or anything close to it!) n Instead, they follow instructions which are written in BINARY n Basically, instructions are given by specifying them BY NUMBER l Known as Machine Language n You can’t understand it, but the machine can!

Programming Languages l Programmers don’t typically work in machine language n Too hard to understand, work productively l Rather, they use high-level Programming Languages to create their programs n These are sets of instructions which are much closer to the language that WE use u Easier to understand, to use u Examples: C, C++, Java, Perl, Python, (Visual) Basic, etc.

Compiling and Source Code l Because computers only understand ML, the original program (in the high-level language) must be CONVERTED to ML n The conversion is known as ‘Compiling’ n We often call the resulting ML code an ‘Executable’ file l The original program, as written by the programmer in the high-level language, is known as Source Code n It’s the ‘Source’ of the program

Source Code- Key points l Source Code n Understood by humans n Can’t be executed by computer n Can be translated into machine language l Executable (machine language) n Can be executed n Can’t be understood easily n Can’t be translated into source code

When you buy software… l What do you get? n Source code or executable? l Why?

If You Have the Source Code, You can: l Understand how the software works internally n Use this knowledge to develop other software l Make changes n Bug fixes n Customize l Make sure there are no bugs, security flaws, etc. l Improve on the software l So, why don’t software companies (usually) give you source code?

Open Source Software l Current movement had (has) a philosophical basis: l Software should be FREE n Not just free as in ‘free beer’ u No cost n Free as in ‘free speech’ u Access to ideas, knowledge u Freedom of expression u The more heads that you have working on a problem, the better the result u When knowledge is restricted to a small few, society is hurt u When knowledge is shared freely, everyone benefits

Open Source Software l Open Source Software is FREE l Variety of license agreements l Best known is the GPL n It can be distributed for free u Although a company can charge for it, they can’t prevent you from distributing it for free n You must have access to the source code!

Growth l OSS has grown dramatically recently n Availability of software n Quality of software n ADOPTION of software

Questions l Where does Open Source Software come from? n Who makes it? n Why?

Answers… l Many sources n Programmers devoting personal time u Outside working hours n Companies developing OSS as a tool in the other services they offer n Companies developing software internally, then releasing it free of charge n Contributions by public institutions, educational institutions n Investment by various parties funding development

Questions l Is the software any good?

Answers… l In many cases, YES! l Much OSS is very useful, well developed n OpenOffice n Mozilla n Linux l In some areas, it is dominant! n Apache web server n MySQL for web database use n BIND DNS server

Questions l Why are companies/governments/ individuals moving to OSS?

Answers l Sick of unreasonable licensing terms n Getting worse! l Don’t want to be locked into one company’s system n OSS typically relies on open standards l Ability to customize software l Can inspect code to ensure that it is secure l Significant cost savings

Questions l Are there companies making money using Open Source Software? l If so, what is the business model for these companies? n What do they make/do? n How do they make money? n Are these viable business models? u How are they doing?

Questions l What are the implications of Open Source Software for ‘closed source’ companies? l How can ‘closed source’ companies fight the threat?

As a Network Administrator… l Why might you want to use OSS? l Why might you be hesitant?

Questions l If OSS is so great, why would I ever used closed source software?

Why stick with ‘Closed Source’? l Belief that corporate developed software is better l Need for support l Concerns about learning curve is change made n Some OSS software not nearly as easy to use l There may not be an OSS package available to do a particular task n Or, may not be as strong as the closed source option

Conclusion l Why selecting software, you need to consider the situation carefully n Look at the needs, and make the best choice l Open Source Software is a good alternative in many situations n Don’t assume it’s bad, because it’s free!