Linux - Module 2: Open source applications and licenses

Module 2Open Source Applications and LicensesExam Objective1.2 Major Open Source ApplicationsObjective SummaryUnderstanding Desktop, Server, and Mobile ApplicationsIntroducing Development Languages and Package ManagementThe Many Faces of LinuxLinux plays many rolesServers are usually unattended and handle data on behalf of other machinesfile servers, web servers, mail serversDesktops a.k.a. clients are more interactive, often graphicalMobile is a tablet or phoneDevelopment is much like a desktop but with more capacity for developmentWeb ServersServe static web pages to clients via HTTPCan also serve dynamic content by adding PHP, Java, Ruby, Python, etcApache and Nginx are the most popular web servers65% of websites use Apache or NginxMail ServersMail Transfer Agents move email between sitessendmail, postfixMail Delivery Agents deliver email to a user’s mailboxProcmail or custom softwarePOP/IMAP servers let clients download mailDovecot, CyrusFile ServersNetwork File System is the native UNIX file sharing protocolSamba allows a Unix machine to emulate a Windows client and serverNetatalk allows a Unix machine to emulate an Apple file serverInfrastructureISC bind is a Domain Name System serverresolves names to addresses and moreOpenLDAP is a LDAP server for directory informationISC DHCP configures dynamic clients through the Dynamic Host Configuration ProtocolDatabasesMySQL and PostgreSQL are relational database serversDatabase servers store and report on structured dataSQL is a language used to query a relational database:SELECT * FROM users;Graphical DesktopX-Windows is the base graphical systemProvides windows and basic primitivesA.k.a. X11 or X.orgWindow managers add menus and window management (open, close, hide, etc)Desktop environments provide window managers and toolsWindow ManagersCompiz, FVWM, Enlightenment, MetacityTakes the basic windows and provides the chrome to move, close, open, etcSwitches focus between running applicationsAdds menus and application launchersDesktop EnvironmentKDE, GNOME, UnityWindow manager + toolsBasic tools like calculator, games, notepadFile managerWorkflow tools, such as shortcuts to launch applications or search the computerOffice/ProductivityLibreOffice is a fork of OpenOfficeIncludes word processor, spreadsheet, presentation package, drawing toolGood compatibility with Microsoft Office file formatsWeb and EmailChromium and FireFox are popular open source browsersThese browsers are also cross platform and popular, ensuring excellent supportThunderbird, Evolution, and KMail are popular email clientsUse POP/IMAP to retrieve emailConsole toolsThe Shell is the primary way of interacting with the systemBourne shell familyC shell familyOther hybrid shells such as ksh and zshText editorsVi/vimEmacsPico/nanoDevelopmentLanguages are either Compiled or InterpretedC, C++, Java are compiledPHP, Perl, Ruby, Python are interpretedTradeoff of programmer productivity vs computing resourcesLibraries bundle common behavior to reduce the amount of code neededOpen Source LicensingExam Objective1.3 Understanding Open Source Software and LicensingObjective SummaryDescribe the various software licenses and their differencesKnow the organizations involved in open sourceSoftware LicensesThe creator of the software owns the copyright to the softwareThe creator grants a software license for people to use the softwareSome licenses take away rights, others give rightsFree Software FoundationStarted by Richard Stallman in 1985Also run the GNU project that provides tools to Linux and other Unix OsesGPLv2 and GPLv3 licenses allow you to modify and redistribute the softwareCopyleft provision dictates that you must share source code to your changesGPLGPL is a popular Free Software licenseGPL is “viral” as changes must also use GPLLGPL lets you link non GPL librariesGPL3 prevents “Tivoization”Using proprietary hardware to circumvent GPL provisionsYou may charge a nominal fee to cover your costs of distributionOpen Source InitiativeBruce Perens and Eric Raymond started the OSI in 1998Copyleft clauses are too extreme, FSF was too politicalOSI doesn’t make licenses, only endorses themFSF licenses are OSI approved, but OSI licenses aren’t necessarily FSF approvedPermissive Free SoftwareAn OSI license must allow the source to be open, to be modified, redistributed, and to be used by anyone for any purposeBSD and MIT licenses allow you to use and redistribute software, or to keep your changes private and use it in proprietary softwareFOSS/FLOSSFree (Libre) and Open Source SoftwareA catch-all termSoftware can be free as in beer and/or free as in speechNon software licensingArt and written material can be licensed, tooPublic domain disavows any copyright restrictionsCreative Commons has a variety of licenses to allow people to use the work under certain restrictionsCreative CommonsAttribution – must acknowledge the authorShareAlike – copyleftNo-Derivs – you may not change the contentNonCommercial – no commercial useCombinations are allowed, such as Attribution-No-Derivs-NonCommercialNo Rights Reserved – public domainMaking money with Open SourceSell services, support, warrantyWork on features in exchange for moneyUse Open Source in your day job/consultingUse work time to fix/improve Open SourceBuild paid plugins/modules (subject to license restrictions)Open Source work lends credibility to your personal brand