MOD2014-Mens-Lecture3
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This is my third in a series of 4 lectures on the topic of Evolving Software Ecosystems, presented during the NATO Marktoberdorf 2014 Summer School on Dependable Software System Engineering in Germany, August 2014.
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MOD2014-Mens-Lecture3
- 6. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 68 Terminology Biological(ecosystem Defini7ons • Ecology:(the/scien$fic/study/of/ the/interac$ons/that/ determine/the/distribu$on/and/ abundance/of/organisms( • Ecosystem:/the/physical/and/ biological/components/of/an/ environment/considered/in/ rela$on/to/each/other/as/a/unit/ – combines(all(living( organisms((plants,( animals,(micro?organisms)( and(physical(components( (light,(water,(soil,(rocks,( minerals) Example:(coral(reefs • High(biodiversity:(polyps,(sea( anemones,(fish,(mollusks,( sponges,(algae
- 9. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 71 Comparison software ecosystem - view 1 shared libraries environment: hardware, OS, external software, developers, users, ... species active projects archived projects Two/dual/views
- 10. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 72 Comparison Two/dual/views software ecosystem - view 2 developers environment: source code, tests, commits, bug reports, species testers end-users debuggers
- 11. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering Comparison( Bipar7te(networks In(ecology( hosts(?(parasites( plants(?(pollinators 73 Periodic report - scientific results Figure 3.3: Example of bi-partite mutualistic relationship Mutual(dependency(and( func7onal(redundancy:( disappearance(of(one(species( may(be(compensated(by( other(species( if(there(is(sufficient(diversity( in(both(layers
- 12. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering Comparison( Bipar7te(networks In(so#ware(ecosystems( contributors(?(projects 74 Projet 1 Projet 2 Projet 3 Periodic report - scientific results Figure 3.3: Example of bi-partite mutualistic relationship
- 13. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering Comparison( Bipar7te(networks In(so#ware(ecosystems( contributors(?(projects 75 Projet 1 Projet 2 Projet 3 Mutual(dependency(and( func7onal(redundancy:( disappearance(of(projects(or( contributors(may(be( compensated(by(others
- 14. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering Ecological(theories(of evolu7on(of(species • Different(evolu7onary(theories( • Natural(selec7on((Darwinism)( • Re7culate(evolu7on( • Hologenome(theory((symbiosis) 76
- 15. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 77 Evolu7onary(theories( Darwinism • all(species(of(life(have( descended(over(7me(from( common(ancestors( • this(branching(patern(of( evolu7on(resulted(from(natural6 selec&on,(similar(to(ar7ficial( selec7on(in(selec7ve(breeding( ! • Example( – 13(types(of(Galapagos(finches,( same(habits(and(characteris7cs,( but(different(beaks Charles(Darwin (1809–1882)
- 16. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 78 Evolu7onary(theories( Darwinism Darwin((1837)• Evolu7on(history(of(species(can(be( represented(by(a(phylogene/c$tree.( • Describes(the(evolu7onary( rela7onships(among(species( assuming(that(they(share(a common(ancestor.
- 18. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 80 Evolu7onary(theories( Re7culate(evolu7on Re7culate(evolu7on( • Evolu7on(history(is(represented(as(a graph(structure( ! • Two(or(more(evolu7onary(lineages(can(be recombined(at(some(level( • hybrid/specia$on (2(lineages(recombine(to(create(a(new(one)(( • horizontal/gene/transfer (genes(are(transferred(across(species)
- 20. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 82 Evolu7onary(theories( Re7culate(evolu7on Re7culate(evolu7on(of(so#ware(?(( ! • horizontal/gene/transfer Transfer/of/technical/resources/(code)/ All(large(so#ware((eco)systems(exhibit((a(large(number(of( accidental(or(deliberate(“code(clones”(and(“code(reuse”( Very(ac7ve(research(domain(in(so#ware(engineering( Mojica et al. “A Large Scale Empirical Study on Software Reuse in Mobile Apps”; IEEE Software 2014
- 23. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 85 Evolu7onary(theories( Hologenome(theory Hologenome(theory( • The(unit(of(natural(selec7on(is(the(holobiont:(the(organism( together(with(its(associated(bacterial(communi7es,(that( live(together(in(symbiosis.( • The(holobiont(can(adapt(to(changing(environmental( condi7ons(far(more(rapidly(than(by(gene7c(muta7on(and( selec7on(alone.(( • Darwinism(emphasises(compe$$on((survival(of(the(fitest),( hologenome(theory(also(includes(coopera$on((through( symbiosis)
- 27. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 89 Ecosystem(Dynamics PredatorIprey6rela&onship • An(instance(of(the( consumer?resource( rela7onship( • Predators((hun7ng(animals)( feed(upon(their(prey( (atacked(animals) Dynamic(model • Two(mutually(dependent( parametric(differen7al( equa7ons (Lotka?Volterra(1925/1926)
- 29. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering • Stability/ • the(capacity(to(maintain(an(equilibrium(over(longer(periods(of(7me( • Resistance/ • the(ability(to(withstand(environmental(changes(without(too(much( disturbances(of(its(biological(communi7es( • Resilience/ • the(ability(to(return(to(an(equilibrium(a#er(a(disturbance Desirable(ecosystem(characteris7cs 91
- 30. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering • Stability/ • the(capacity(to(maintain(an(equilibrium(over(longer(periods(of(7me( • Resistance/ • the(ability(to(withstand(environmental(changes(without(too(much( disturbances(of(its(biological(communi7es( • Resilience/ • the(ability(to(return(to(an(equilibrium(a#er(a(disturbance( ! Higher(biodiversity(favours(these(characteris7cs Desirable(ecosystem(characteris7cs 92
- 31. July?August(2014(—(NATO(Marktoberdorf(Summer(School(—(Dependable(So#ware(Systems(Engineering 93 Desirable(ecosystem(characteris7cs( Biodiversity Biodiversity((of(species)(measures( the(degree(of(varia7on(of(species( within(a(given((natural)(ecosystem( • Many(different(metrics:( • species(richness( • species(evenness( • Shannon(diversity(index( • Simpson(index( • … Goal:(Use(these(and(related(measures(to(study(maintainability(and( survivability(of(so#ware(projects(within(their(ecosystem