Michael J. Lewis, Adam J. Ferrari, Marty A. Humphrey, John F. Karpovich, Mark M. Morgan, Anand

20 Pages·2002·0.08 MB·English

eh tn iraepp aoT lanruoJ fo lellar a dPdegntnauibtiurptmsoiCD . 3,002
Support for Extensibility and Site Autonomy in the
Legion Grid System Object Model 1
Michael J. Lewis † i,mra ad.rAJreF * ye ry h t,p.rmAauMH * KarFpJ.oo vhinc, h * ,
MorMMg.aa rnk * , Anand Natrajan * gnouT-neyug Nhn A, * GWlaSe,s.n s no n * dn a
wahsmir G. SwerdnA *
* }[email protected]|g iwnaisas.oend u| nguyen | anand | mmm2a | jfk3w |h umphrey| ferrari {
Department of Computer Science, University of Virginia
† ude.notmahgnib@siwelm
notmahgni B -YNU S,ecneic Sretupmo Cf otnemtrapeD
sdrowyeK : objects, distributed wide-area, computing, distributed Grid,
,era .weyetmliodsndoitmua
tcartsbA
dirG gnitupmoc si eht esu fo egral snoitcelloc fo ,suoenegoreteh detubirtsid
resources (including machines, databases, devices, and users) to support large-
elacs snoitatupmoc dna aera-ediw atad .ssecca ehT noigeL metsys si na
noitatnemelpmi fo a erawtfos erutcetihcra rof dirg .gnitupmoc ehT cisab
philosophy underlying this architecture is the presentation of all grid resources as
.eni hlcaaum t,rsisvel ms, atefenlos egannoipsmoc
s’noigeL erutcetihcra saw dengised ot sserdda eht segnellahc fognisu
and managing wide-area resources. Features of the architecture include: global,
derahs ;secapseman troppus rof ;ytienegoreteh ;ytiruces aera-ediw atad;gnirahs
aera-ediw lellarap ;gnissecorp elbatsujda-noitacilppa ;ecnarelot-tluaf tneiciffe
gniludehcs dna evisneherpmoc ecruoser .tnemeganam eW tneserp eht erocngised
ecxLrtaeieritogtncsthfsiishshe iociiue tnabtoea e flioensno lfc dwci t iututsyrh e ,
.ymonotua dirG smetsys erawtfos tsum eb elbisnetxe esuaceb on citats tesfo
system-level decisions can meet all of the diverse, often conflicting, requirements
of present and future user communities, nor take best advantage of unanticipated
future hardware advances. Grid systems software must also support complete site
,ymonotua sa ecruoser srenwo lliw ton nrut lortnoc fo rieht secruoser revo ota
system.dictatorial
1.T heL egionp rojecti sp artiallys upportedb yN FSC DA-9724552,N SFC areerA wardA CI-0133838,N SFE IA-
9911099D,A RPcAo ntrac#tN 66001-96-C-8527D,Og Er anDtE -FD02-96ER25290D,Oc Eo ntracSta ndiLaD -
9391, Northrup-Grumman (for the DoD HPCMOD/PET program), DOE D459000-16-3C, and DARPA (GA)
SCH 607305A
no i.t1cudortnI
dirG smetsys era gnimoceb ylgnisaercni tnatropmi rof tnerruc tra-eht-fo-etats snoitacilppani
sniamod morf ecnamrofrep-hgih cifitneics gnitupmoc ot .ssenisub ynaM fo s’yadot dirgsmetsys
]7[]22[]92[ era tsuj gninnigeb ot kcatta eht segnellahc fo ylurt ediw elacs tnemyolpedssorca
egral srebmun fo setis taht era ylno ylesool detcennoc dna evah on lartnec gniganam .ydobroF
hcus ,smetsys dirg erawelddim—erawtfos evoba eht lacisyhp secruoser dna wolebresu-dne
si–snoitacilppa .lativ tuohtiW dirg smetsys ,erawtfos gnitcurtsnoc snoitacilppa taht tiolpxeeht
impossible.or difficult be will grids new these of potential full
srengised ehT .ymonotua etis dna ytilibisnetxe edulcni smetsys dirg fo stnemeriuqer lacitirC
t cte s ior fddednas o nehenwmdt aitrat,einfmrpcfrtr eoeaoes gedsdvsvy.rneossuareetprsuoufM
er ustecgunraths caerr fa,nni ogmnmiogcn a,mreomrift -dnaw oosldegnah cd nsaedargp uotwen
,snoit asrn eownieetngaru gdinfanoc wen ss e.csceaicilop A dirg metsys tsum tpada otgnignahc
s, sesr h dreetcenii saicaulduhhrm qpn twueeepdaeod hruer sststademcwir eutretrfgbstoysssnoc
ecruose rf oytilib aeh ttcirtse rto nna csmetsy sdir g,eromrehtru F.lao gngise das aytilibisnetx ehtiw
ecruoser sselnu deveihca eb tonnac smetsys dirg elacs-egral ylurT .secruoser rieht lortnoc ot srenwo
,se ce rno u ihn ro,mwaeis . rcseesgoeuhre.tttceer(d u rolis oeed rhr e ytts wolnreotloerlucnalfwao
woh dn ane hyweh tnac e b,de sduna wo hhcum ti l. l)yi tmwhsoc onuncoSat cuoasla eb desuot
eg ayntaimxelpmoc ni dirg .smetsy secniS lac ollennosrep era yllacipy terom tpgendianiatniam
ycil ospsec ceacruos erret lyallaciman y odmte hgtniwol l,arotartsinimda-di rnaga hstecruos errieht
.ytilibaliava ecruoser retteb rof sedivorp
,dyaeti p i nsd otsfiied mla rogs edeeeeransitvhvibo arsetiV,bgydnn-sUoa tincgaeejLbo
erawtfos erutcetihcra taht sesserdda ytilibisnetxe dna etis ymonotua sa ssalc-tsrif ngised
.stn enmo eisrgeieduLiqveorrp a elg nliasu terniivhca mweiv s us oefeconreugo ostreaerhttehera
trap fo a dirg .]61[]51[ A noigeL dirg stsisnoc f o,snoita t ,srskorrteoctweuvplmeolclraerpaups
sretupm odd centrz aneideplemuatpsiciceuenqpneso cyb a yteirav f o.skr onwotie gnseeLlkcata
- e,deicwnarelot-t leulabfatsujda-noitaci lgpnpiadu l,csnmiel bsomrep tdseytsubi re tgfesnodiaidrw
aera lellarap ,gnissecorp ,ytilibareporetni ,ytilibalacs ,ytiruces tneiciffe ,gniludehcs dna
s e sidetc n srieahrolhcepo tavppdoiuerdss pa.pbta-n tencmA eeejgcba roneuavomissenreherpmoc
seitiroirp fo ,sresu ,srepoleved dna ecruose r.sredivorp hcaE dirg ecruoser si na .tcejbonoigeL
senifed smsinahcem rof secivres hcus sa tcejbo ,noitaerc ,gniman ,noiteled etats,tnemeganam
esrheotciv reess enfhootitatnemel p emehittad n tasom en tonudobitaco vdnoih t dennmoaitargim
.esu rieht rof seicilop
ehT ynroaimtiurbpirtn ofco siht repap si ot ebircsed eh tseitreporp fo eht noigeLtcejbo
ledom dna .erutcetihcra ynaM tnatropmi seussi ni noigeL era dnoyeb eht epocs fo siht.repap
cificep Ssaera fo eht noigeL metsys evah nee bdebircsed ni ,ht pgendidulcni eht ytirucesledom
,]8[]5[ gniludehcs ,]42[ ecnarelot-tluaf ,]43[]33[ O/I smetsys ,]04[]52[ eht emit-nuryrarbil
erutcetihcra ]83[]9[ dna troppus rof ecnamrofrep-hgih gnitupmoc .]13[]03[]41[ nI siht,repap
on3itc e.Syhposoli hdp n,astniartsn o,csevitcej b,ongis endoig elLevel-hg ieh hstessucs in2doitceS
s e cse tulth ne cden te oron4 eodedh.oiitjrosntsc gtpbtme aeeeceno rnshLeicfpostSnoiaoglcecL
noig emLe tsstynsemele ta a hgih .lev eon5li tsctenSeser pemos cisab noi gseeLcivres dnawoh
yeht dehergvaueo i rdhe hechttnatriobfmfo ecf o.msettcse y jesebdWou l hcdtneiotwcaklreorw
.)on7itceS( yrammus a dna )on6itceS(
yhpo ss otdlnniiahaPr t,ssneovCit cne oj.ib2gOeL
Given that computational grids are composed of resources that span multiple administrative
domains, there exists a complex set of design principles for grid systems. These principles have
Page1
.erutcetihcr anoige Leh tf onoitadnuo feh tneeb
• Site autonomy : noigeL si desopmoc fo secruoser denwo yb ynam ,snoitazinagrohcihw
ylreporp tsisni no gniniater lortnoc revo rieht .secruoser roF hcae ecruoser eht renwo sielba
to limit or deny use by particular users, and specify when and how it can be used. An
tnatropmi tcepsa fo ymonotua si noitatnemelpmi ,noitceles .e.i lortnoc revo eht edoc desuot
tnemelpmi metsys .secivres setiS era elba ot esoohc ro etaerc rieht nwo noigeLstnenopmoc
.seicilo pecruose ryrartibr atnemelpm iot
• elbisnetxEeroc : noigeL tsum tius eht ediw yteirav fo tnerruc resu sdnamed dna eb elbapacfo
evolving to meet unanticipated future needs. Therefore, mechanism and policy are realized
via replaceable and extensible components, including and especially our core system
components. This model facilitates development of improved implementations that provide
dedda-eulav secivres ro cificeps-etis ,seicilop elihw gnilbane noigeL ot tpada revo emit ota
changing hardware and user environment. For example, integrating Legion with the Storage
ecruoseR rekorB ]82[ saw a elpmis rettam fo gnidnetxe eht eroc metsys tnenopmoctaht
.y re og ota etiras esso teBhuotdal RtpsnddsSeenar- akahcab
• elbalacS erutcetihcra : Since Legion was designed to build grid systems consisting of
snoillim fo stsoh dna ,stcejbo ti sah a elbalacs erawtfos .erutcetihcra nI rehto ,sdroweht
metsys si ylluf detubirtsid htiw on dezilartnec serutcurts ro .srevres sihT ,swolla rof,elpmaxe
.snoitar enpooitacinum meodciw-d iervgisne ptxueoh tnio wi d gsoe oett detLswdboeahn
• ,esu-ot-ysaE sselmaes lanoitatupmoctnemnorivne : noigeL stcartsba eht ytixelpmoc fosti
erawdrah tnemnorivne dna seifilpmis eht noitacinummoc dna noitazinorhcnys devlovnini
parallel processing. Machine boundaries, for example, are invisible to users when using
mroft aIslP.’pMmn-eostissgoyersLc
• ,elgniS tnetsisrep tcejbo ecaps : gnipoleveD lellarap dna detubirtsid smetsys ni na
tnemnorivne tuohtiw a elgnis eman ecaps rof gnissecca atad dna secruoser si llits a
tnacifingis elcatsbo rof sresu fo ynam dirg .smetsys gnivaH a edutitlum fo tniojsideman
secaps yltaerg sedepmi gnipoleved snoitacilppa taht naps .setis yB ,tsartnoc lla stcejbo nieht
noigeL metsys nac yltnerapsnart ssecca lla rehto noigeL stcejbo tuohtiw drager ot noitacolro
,noitacilper tub tcejbus ot ytiruces .stniartsnoc sihT si ,lufesu rof ,elpmaxe ni gnitaercedoc
repositories where any host in the grid can execute an application stored there simply by
gniwonk eht eman fo taht noitacilppa ,.e.i( eht noitacilppa deen ton eb derots no ehtlacol
.)derot ss inoitacilpp aeh tereh wnoitaco llacisyh peh twon kto ndee ntso heh tdn aenihcam
• ytiruceS rof sresu dna ecruosersrenwo : Security is a fundamental aspect of grid systems,
htob ot tcetorp eht ytirgetni fo resu snoitatupmoc dna ot evreserp eht ytilibaliava fo
.secruoser noigeL saw dengised no eht elpicnirp taht ytiruces tsum eb tliub ylmrif otnieht
noitadnuof fo a dirg gnitupmoc .metsys fO ,esruoc on elgnis ytiruces ycilop si elbatius roflla
sresu dna os noigeL sedivorp smsinahcem taht wolla sresu dna ecruoser srenwo ottceles
seicilop taht tif rieht ytiruces dna ecnamrofrep sdeen dna teem rieht lacolevitartsinimda
.stnemeriuqer roF ,elpmaxe noigeL stroppus noitacitnehtua desab no noigeL slaitnedercdna
.]02[ sorebreK
• ecnarelot-tluaF : nI a elacs-egral dirg ,metsys ecruoser eruliaf ,stsoh( noitacinummoc,sknil
,sksid ).cte si .ecalpnommoc ,eroferehT eht noigeL metsys flesti saw dengised otsserdda
failures, through fault-tolerant components and dynamic system reconfiguration, as well as
yb gnidivorp smsinahcem ot troppus a ediw egnar fo resu noitacilppa ecnarelot-tluaf.sdeen
For example, important system components that were executing on hosts that have failed, can
.st s,oehlbar e,proe hnntoooi gdyeebLtrat seebr
Page2
ehT sevitcejbo detsil evoba erew demarf yb lareves tnatropmi lacitcarp stniartsnoc tahtdediug
:t eagwhntiw odnekngi ssneaodwi g.enLgi sreudo
• tonnaC egnahc tsoh gnitareposmetsys . snoitazinagrO lliw ton timrep rieht senihcam oteb
desu fi rieht gnitarepo smetsys tsum eb .decalper ruO ecneirepxe htiw htob noigeLdna
.sme tgsnyist a t rsn lnp temaeioofspecbutooo tbh ds tiysars whgeotrh os ]ft7ea1bt[neM
• Cannot change network interface . tsuJ sa ew tsum etadommocca gnitsixe gnitarepo,smetsys
eht ngised fo noigeL semussa taht ew tonnac egnahc eht krowten secruoser ro ehtslocotorp
.esu ni
• Cannot require Legion to run in privileged mode . oT tcetorp rieht stcejbo dna,secruoser
pripvoislseilgboelwsee. st the with run to softwLaergeir oenq uirsei tes and usersL egion
ruO llarevo evitcejbo ni eht ngised fo noigeL saw ot etaerc a dirg metsys taht saw elbatius otsa
many users and for as many purposes as possible. One thing was clear: a rigid system design—
eno ni hcihw seicilop erew ,detimil ffo-edart snoisiced erew ,detceles-erp ro lla scitnameserew
pre-determined and hard-coded—would not achieve this goal. Indeed, if Legion dictated a single
ediw-dirg noitulos ot tsomla yna fo eht lacinhcet ,sevitcejbo ew dluow evah dedulcerpegral
sessalc fo laitnetop sresu dna .sesu ,eroferehT ew dengised noigeL ot wolla sresu dna
sremmargorp eht tsetaerg ytilibixelf ni rieht ’snoitacilppa ,scitnames gnitsiser eht noitatpmetot
dictate solutions to many system functions. Users are able, whenever possible, to select both the
dnik denhat level .tso cdn anoitcnu fneewte bsffo-edar tnw orieh teka mo tdn a,ytilanoitcnu ff o
seificeps ledom tcejbo noigeL ehT .erutcetihcra metsys eht ni detsefinam si yhposolihp sihT
erofe rmeeh tt es;eryshosttcc e ejsrb'oomc en tofesiohyttsatneme lytteptuohmibntilanoit cenhutf
stsisnoc fo ,elbi senlebtaxe ec.asltpneernopmo cnoigeL sedivorp t lsunaofietdatnemelpm ifoeht
t csr erooeletgesasur u, odecawne etd. s emonetetIsahu gt sie trlrhoebagnsouuo h,tsltac eejrbooc
.sdeen cificeps rieht teem taht snoitatnemelpmi tcejbo tcurtsnoc
l etdcoeMjbO/s snao li.Cg3eL
noigeL si desab-tcejbo ni taht hcae fo sti stnenopmoc si na .tcejbo noigeL stcejbo era
tnednepedni fo eno ,rehtona hcihw snaem taht yeht era tniojsid ni ecaps-sserdda dna
etacinummoc htiw eno rehtona aiv etomer dohtem .noitacovni hcaE noigeL tcejbo sgnoleb ota
.tcejb onoige L aflest is issal chca edn assalc
h;csfueoms s n ameose l oliehfcrrog mtoefresowL’col petdc o enmhj oc bfiueoogMhetL
ytil id be s itl itsaelangve ho eev. owpsllesdtsse-l teea dm-scrrlyerieeclrtejdlossbiaFyuosusnsouc
,elpm anxoeig esLessalc eerlabisnop sreorf gnitaerc dna gnitac orli eshetc nsattcsenjibo( fotaht
stcej bnooig eeLr oec h.Tseicil otpnemeca ltpcej bdo nyatiruc eestairporp pganitcel ers odf n)assalc
edivorp smsinahcem taht wolla level-resu sessalc ot tnemelpmi rieht nesohc seicilop dna
.smhtirogl aehT yhposolihp fgo nlietvaellu-smp eaytccsniyelsop ni ,e leblibsaneectaxlepsesralc
debircsed (stcejb oero cnoige Leh ty bdetropx esnoitarep oevitimir pf ote seh ty bdetroppu s,stcejbo
snoisi cyecdi leotpairporpp agnniis o rpfemog inesahedttanim iylleevitce f,f)eon4i t lcnieia Stneid
.repoleved metsys dirg eht rof seitilibissop fo egnar ediw a sedivorp dna
er astcejb ossal C.tcejb ossal cst iy bdegana mdn adenife ds itcejb onoige LyrevE sreganam
dna y csirleokpam dna yt i gl gnir nibo, itifsltas deeavnwncveioeanertpn alccset-aevsmranehitsys
gn i,tm a e svtghsg icntsndteiein cjdrdaaabidnteovdiad(o abdrtpaht s ilufes uni ethxtetn ofcoeht
siht ;stcejbo ssalc nwo rieht enifed ot sresu segaruocne noigeL .stcejbo tneilc rof )locotorp tropsnart
nac eb sa elpmis sa a elgnis dnammoc taht setaerc a wen noigeL tcejbo rof a s’resugnitsixe
.noitacilppa esehT owt ssalc—seruta etfcejbo tnemeganam fo rieht secnatsni dna eht ytilibafo
snoitaci lsprpeammargorp ot tcurtsnoc wen edivorp— syetsislailbcixelf ni gninimreted wohna
Page3
no isteavcaihlep bpdan are httrroupfpu seht ynhopiogseoLl ifyh otpginliilbbia xnneeilf ehtdnik
.ytilanoitcnuf fo level dna
h cnao Eissgsee anLeli ccfeaehf dtrr eo.tfsn ei sscsttnisiahitTs snfnooic e hdtohstlelmac
taht nac eb edam no stcejbo fo taht .ssalc sihT ecafre tsneidulcni yerhottadencaamf-rsestanlic
)re1ugiF( dna eht cificepyst-islsaanlocitcnuf 1 . ehT yrotadnam- sescaalfcretn isessapmocneeht
sdoht eteman his tmusroeeiitrceaidvl orpof .eshetcn as tisshenTdiulcni createInstance() ,
shectiahew rac e cwnean tfsoni e hstsa lsdcnn rat unet eheed trmnn aeow npieretnodafnctioalht
ecnatsni dellac( a DIOL ro noigeL tcejbO reifitnedI - ees noitces ;)1.on5itceS
)(secnatsnIelpitluMetaerc s,e clshnaec artifteahosvewner isce hstsal cta leucfneosu(
;) sd tnsl r aregoee lnhgbfrliormooaccaufralnalpp activateInstance() s e ,thacnriaghiwm
gn ietcsniaxtesni ot a we nnoitacol ro stratser na ecnats ntiaht dseatwavitc aoetd e.esrefcruoser
noita e errhcotl iroaettl l eaghcntiwo l,lsanois rleavre v seyaslhlau tscnaoitc neuef rehst ehfhcotaE
dna tn e.mseecsaslepcor proF ,elpmaxe eht rellac nac etacidni eht tsoh no hcihw eh)ts(ecnatsni
,serutcetihc r,asdee prsossecor ps(ts oehlbatpec cfsaocitsiretcara he chytfice pr,sodeca ledpbluohs
.).cte ehT addImplementation() dna )(noitatnemelpmIevomer snoeirtucgniuffnoc
d eyslulaci p eysrtnaoitc neusfe hste(cnat s s nr teiolis fluticwe jsbso a elshcntoitatnemel phmciihw
. ) nsdoreiettlea igtnpr nAmayseotbimc-en lonpio mgieiethLa ttn nofeiosgeerLp.ee rlnbaatucexe
ehT getBinding() lac is seotymtnhaepndnepedni-noi tn aofciootlals ntearhrot tpspnuosit cnuf
reht olareve ser aereh T.1.on5itceS ni debircsed sa ssecorp gnidnib eht gnisu secnatsni fo sesserdda
sn oti otnncw(nouh fs n)ire1 utn g aosiwthitFout tn lonae elb omievaaoirlhettoctidafrncntaoielr
scit sf io,rse et ehcc’ hcnas,tu a rsesttraa c nsihlsa,’eneccaftsrihrser t eocuedthnchnnartaitisenhit
.)treni ro evitca( etats tnerruc
s tn conreiioejtfhbatom rtonfenm iey gc dysa iwnfrnsl oaieaeool csmsptleeusalpaislhcW
n o,idgierL g t tidnle uiron owesefvrbneos cuonti evah oettaer ca w e sntscael jcrboo fhcaewen
eht elihw ,tcaf nI .dliub ot dehsiw yeht tcejbo noigeL fo epyt secnatsni yrev mrofrep netfo ssalc a fo
, stnn o essi ,r s etseema.v c trfrlslnnrcofocneouaefifsosifljedreimgibrenteemoepichLihfntsTeudf
ssalcsattceemjbo . ssal csattcee Mjebdoivorp a msinahce mrof sresu ot poleved wen ,stcejbotub
esue rgnitsix essalc . yttc iesljsabanoloci atstctencMuefjbo era ssalc stcejbo eso hswecnatsniera
sevlesmeh tssalc .stcejbo tsuJ sa a lamron ssalc tcejbo seganam dna ssnnoiiattantinaemmelpmi
ho styi ewthcte j s wb raaeon ehn eas.hutWce jsbsoalc as t eae oom,oodsstecnat s sn rtisoitfcejbo
etarop rootcnnii eht ,dirg yeht etaerc a we necnatsni fo a ssa l.ctacteejmb osihT tcejbo si assalc
tcejbo taht nac neht eb desu ot eganam eht s’resu wen .tcejbo oT esu a ssalcatem ,tcejboa
class ClassObject {
LOID createInstance(< placement info> );
LOID Array createMultipleInstances(int n, <placement info> );
int activateInstance(LOID instance, < placement info> );
int deleteInstance(LOID instance);
int deactivateInstance(LOID instance);
int addImplementation(LOID implementation_object);
int removeImplementation(LOID implementation_object);
Binding getBinding(LOID instance);
Binding getBinding(Binding stale_binding);
};
FIGURE 1. A subset of the Legion class-mandatory interface
1.N otet hata no bjectc and isallowa nyf unctioni nvocationr equest,t ypicallyb asedo nt hec redentialso ft hec aller
(see section 5.4). This is especially relevant to the system-level functions implemented in core objects[5].
Page4
remmargorp ylpmis sllac )(ecnatsnIetaerc no eht etairporppa ssalcatem ,tcejbo dna
serugifn oech tgnitlu ssesralc tcejb ono ihtt aistwtnceemjeblopm irof enhotitacilp pnai.noitseuq
ehT wen ssalc tcejbo neht stroppus eht ,noitaerc ,noitargim ,noitavitca dna noitacol foeseht
noitacilp psatcejbo ni eht rennam denifed yb sti ssalcatem .tcejbo noigeL sedivorp a eciohcfo
ss a,lsctacteejmb oe hstecnatsn ifo hcih wtropxe e hy,treocta afedrmne aattsmnu-ibsesdailvcorp
.ecafretni taht rof ytilanoitcnuf tnereffid
ro F,elpma xeemo sstcejbo yam eb dengised ot eci v srdneooshitteamco vynb ignitaerca
wen ecnatsni ot ssecorp hcae .tseuqer rehtO stcejbo yam daetsni tcerider stseuqer ot eno foa
rebmun fo gnitsixe ”ecivres“ stcejbo rof .gnissecorp hcaE fo eseht ”ecivres“ seicilop dluoceb
gnit a, lsdusnpaaol pcea t tg aden.eiemisc r dtsnnapyf da aaioBoweeeltr ebrhcspanmctanpetiaem
sno itti a ft ,onhnetomii ewtr laa rp claemaiupilcopi lptnear avayce pldeitsaaeer cn atce jhbtoiwa
.ycilop ecivres ralucitrap
ssalC stcejbo dna ssalcatem stcejbo pleh eveihca ytilibisnetxe dna etis ymonotua nia
noigeL .metsys noigeL seod ton etadnam eht sdnik fo stcejbo taht era dettimrep nihtiw adirg
.m estrseyss Uera eerf o t esttaceerjc bfoo r iee cheittoa h rdcmonepahr tosoc’ttnnncioieijgbeoL
tnem e.gkarnoawm e,mraervfoeroM sresu yam osla esoohc neewteb lareves tcejbtonemeganam
,s ntydoro ceet iieehtnyeg tjtaiahe,ab rm tLyeoeso slr cap.rylcenrsenavoomsanaceumihntFisys
secn af stortsicneei hjst yba .toyeierl hia st s nne , enoId dtmdoiisiceitviretgcohgpsenrtsyLupesfr
hscsruaes v ]drs6ne n3as aa[evesaBiJrp r h escstmuanesE tescyis vtbrnee ewsr ecaoreltorimmis
SSOBJ .]32[ ehT seicilop taht nac eb tes no ssalc stcejbo netfo tcelfer eh tstnemeriuqer foetis
.ymono tr uo,aFelpmax eti si nommoc ot t esseicilo pno ss asltccej bt oathctirts ee rhntoitaercfo
.dirg eht ni senihcam eht fo tesbus a ot secnatsni rieht
se ptycTe jeb rO.o4C
A noigeL dirg stsisnoc fo a tes fo elbareporetni stcejbo deganam yb rieht .sessalc emoSstcejbo
encapsulate the applications that users wish to run on the grid. Other objects provide important
level-metsys ytilanoitcnuf taht sesae eht ssecorp fo gnipoleved noitacilppa stcejbo ybgnidivorp
abstractions of important elements in grid systems. We discuss these core object types and their
bseylsogtwre.imd a in role
stcejb Otso H1.4
noigeL tsoh stcejbo tcartsba gnissecorp secruoser ni .noigeL yehT yam tneserper a elgnis
,rossecorp a ,rossecorpitlum a xunil ,xob a yarC ,E3T ro neve na etagergga fo elpitlum .stsohA
tsoh tcejbo si a s'enihcam evitatneserper ot :noigeL ti si elbisnopser rof gnitucexe stcejbo noeht
machine, protecting objects from each other, deactivating objects, and reporting object
exceptions. A host object is also ultimately responsible for deciding which objects can run on the
encapsulation.policy security of points important are objects host Thus, represents. it machine
t ssotHcej beora tnnaat rtyortpaimpli i gbdfninoisadn ieeyvttmoxioresnpot unainoigeL
.sdirg nI noitidda ot gnitnemelpmi eht yrotadnam-tsoh ecafretni erugiF( ,)2 tsoh tcejbo
snoitatn enmaeclpmi eb tliub ot tpada ot t n sentroneieftmfunicoder xidevnnae ti utsnereffiedtis
seicilop dna gniylrednu ecruoser tnemeganam .secafretni roF ,elpmaxe eht tsoh tcejbo
noitatnemelpmi rof na evitcare tnnoiitatskrow sesu tnereffid ssecorp noitaerc smsinahcemnaht
Page5
snoitatnemelpmi rof lellarap sretupmoc deganam yb hctab gniueuq .smetsys sihT epyt fo
class Host {
ObjectAddress startObject(LOID object, LOID impl,
OPRAddress opa);
void deactivateObject(LOID object);
ObjectAddress getObjectAddress(LOID object);
};
FIGURE 2. Basic Legion host object interface.
y tsi wlnoiolbili gas tenssLetotchxeej boot tpad an ogosintlti eug gdcrdnoeeeimxmneeeibfreodf
.]01[ erutcetihcrA secivreS dirG nepO eht
elihW tsoh stcej beodivorp a mro feicnaufretni ot tner e,efscftrinudeomsneorryievhnte
sei ctinleompe gea cnyr atudmio nrsseauerc crer oedoe tsifde vni co oevsrsa ronulrpraoaopesfmer
yal nwool l oadtezimots u ecnb ancoitatnemelp mticej btos o,ahelpma xre o.Fdi rngoig enaLihtiw
det ctierst sfe ors,s rys selet tse cst cuvs co coeisnahditjteae rbaccs.toncaesra bcenearrotuloAser
sci tesdi or.ceg t.gcena(irtaphecc cy alsnnoo ittcaet jnt beagomhnet ilnypirmaritanceo-dcfoocorp
]23[ gnitartsnomed niatrec ytiruces ,seitreporp ro gnitcej esrnoitatnemel pgmniiniatnocniatrec
.)sllac metsys ”detcirtser“
redisnoC owt fo ruo snoitatnemelpmi rof tsoh .stcejbo ruO tluafed tsoh tcejbo siyrev
ti—elpmis stnemelpmi a evitcirtser-no nssecca ycilop dna sesu eht xinU ssecorptnemeganam
.eec.aif(retni fork() , exec() , kill() e lhpgomu tio.shstt lcg Aeng ji n)bpdi opntroarotafsts
stc esljelbtaou cteix—eyti rs du mfecnroteie istyml ie.l rst ewInssvagiael ihs fss,iethdntemelpmi
yna mo tssecc awoll atah tstnuocc a”cireneg “gnitaer cro flufes uelih W.d ires uxin Uelgni sarednu
,sre ssuiht epyt fo ts osh wsotlclea jtmbnoo ernrfoeif gfseirLdes ueyrl elofat rihetttninewitopro
t ct teloss jutdopeb anhahonfemtoetidxteatnem eelvpimt ia. ne srtn’eaArt teles hanetinomonaaxe
noigeL sresu ot ralucitrap xinU sdi-resu nehw gninnu rtnereffid 'sresu .stcejbo sihT tsohtcejbo
.sresu ot egasu ecruoser fo noitubirtta dna noitalosi tcejboretni retteb sedivorp
dsnmaet sgynsiu ehuc qtrsaot bfs. og,h.setce jt mbsfuooorh tdc eeatpnsemel pe mveiaWh
noi t,ae ccdinnlaapmp ra,oyftr ie mrpf,eu fk tc, sosssestte iwyseasdrros nhoaodTithrfnNhticWam
.ytiruces nA tnatrop mticepsa fo noigeL etis ymonotua si eht modeerf fo hcae etis ot tceleseht
gnitsixe tsoh tcejbo noitatnemelpmi taht tseb stius rieht ,sdeen dnetxe eno fo ehtgnitsixe
snoitatnem eoltpmi tius ,lsatcnoelmeriu qreor ot tnemelpmi a wen tsoh tcej bgonitrats morfeht
tcarts b.aecafretni nI gnitceles dna gnirugifnoc tsoh ,stcejbo a etis nac lortnoc eht esu forieht
.stcejbo noigeL yb secruoser
st c te2lj.ub4aOV
tluaV stcejbo era elbisnopser rof gniganam rehto noigeL ’stcejbo tnetsisrep snoitatneserper
(OPRs). Much in the same way that hosts manage active objects’ direct access to processors,
stluav eganam treni )detavitcaed( stcejbo no tnetsisrep .egarots nI a lacipyt noigeL metsyseht
rebmun fo stcejbo yam eb sredro fo edutingam regral naht eht rebmun fo .srossecorp,eroferehT
while some Legion objects will be evitca no srossecorp deganam yb tsoh ,stcejbo tsomstcejbo
will be treni , dna evah rieht tnaveler etats derots ni a tluav .tcejbo A tluav sah tcerid ssecca ota
egarots ecived ro( )secived no hcihw eht sRPO ti seganam era .derots A s’tluav deganamegarots
yam edulcni a noitrop fo a xinU elif ,metsys a tes fo ,sesabatad ro a lacihcrareihegarots
tnemeganam .metsys ehT tluav stroppus eht noitaerc fo sRPO rof wen ,stcejbo slortnoc sseccaot
existing OPRs, and supports the migration of OPRs from one storage device to another. Vault
stcejbo edivorp rof ytilibisnetxe yb gnitneserp na noitcartsba fo a egarots .ecruoser nehW awen
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epyt fo egarots metsys sdeen ot eb dedda ot eht ,dirg a wen tluav tcejbo nac eb .detaerc ecniSsiht
.st cgenjib toehs lti,bixe iwectltail afiep rwbmyeortcon tit a redtlohn clpta teixmwljweeubnaov
s ssat lceCegjab nota nmeehmtng ifso ssatlu a:v soetc nnaethswni na tcejbo s,idetaesrtci
tluav s inesoh cyb se ’h.ttscseaj lbdecoeh tT tcsleeultaeavser ca we nytpm eRPO rof e,httcejbo
dna seilppus eht tcejbo htiw sti eht ”sserdda“ fo sti RPO dellac( eht APO rof tcejtbnOetsisreP
st rtlt ocu e afeasg w,lvsrseseaatnesltitca rtn,gc eyienhlmjawrbaol i.m)isSse rndodiAtatneserper
.) 3erugiF (ecafretn itcartsb atlua vnoige Lcisa beh ty bdetroppu ser aseitivitc atlua veseh T.RP Osti
ehT createOPR() doht esmtcurtsnoc a wen ytpme ,RPO setaicossa siht RPO htiw ehtnevig
,DIOL dna snruter eht sserdda fo eht wen RPO ot eb desu yb eht ylwen detaerc .tcejboehT
class Vault {
OPRAddress createOPR(LOID object);
OPRAddress getOPRAddress(LOID object);
LinearOPR getOPR(LOID object);
void giveOPR(LOID object, LinearOPR OPR);
void deleteOPR(LOID object);
void markActive(LOID object);
void markInactive(LOID object);
};
FIGURE 3. The Legion vault object interface.
getOPRAddress() fyo nhat idwetaicos sRa PeO h ftnooitac oel hetnimret e oddte s sudioht em
sti deganam .stcejbo ehT giveOPR() dna getOPR() sdohtem refsnart a deziraenil,.e.i(
)elbissimsnart RPO ot dna morf ,stluav ,ylevitcepser gnitatilicaf tcejbo .noitargim ehT
deleteOPR() dohtem si desu ot etanimret a s’tluav tnemeganam fo na .RPO ,yllaniF
markActive() dna markInactive() yfito neht tlua vnehw na tcejbo si evitca .reovitcani
de td pe sys rtwrsseeo locet hg eulnrc otdne ralepeeteivsova mjhliRtsob twtPsicofocOhonaTkni
tne my n, eeda selhecoebptstcmuriu oesgear rlso asto cestlocolcra tsntocc etj lbeu oca.nvsimSrof
,satou qniatre co tegas ugnitcirtse r,elpmax ero F.secruose resoh to ttcepse rhti wycilo pcificeps-etis
.ymonotua etis selbane rehtruf ,.cte ,stcejbo ro ,sresu
sntocietjabtOn e3m.e4lpmI
noitatnemelpmI stcejbo etaluspacne .selbatucexe ehT elbatucexe flesti si detaert hcum ekila
Unix file (i.e., as an array of bytes) so the implementation object interface naturally is similar to
a xinU elif :ecafretni read() , write() , and sizeOf() (Figure4). Implementation objects
class ImplementationObject {
ByteArray read(size_t startByte, size_t szToRead);
size_t write(size_t startByte, ByteArray data);
size_t sizeOf();
};
FIGURE 4. The Legion implementation object interface
era osla ,ecno-etirw ynam-daer on—stcejbo setadpu era dettimrep retfa eht elbatucexe siyllaitini
.tnetsisnocn ignimoce bselbatucex edetacilpe rf oregna do ns iereh t,erofereh T.derots
y nta,iummbroft aell p gr eno adifeoslcbatuc enxieat nyolclaci psyttce jnbooitatnemel pmI
,elpmax ero F.tso hralucitra p an otcejb on aetaitnatsn io tyrassece nnoitamrofn iyn aniatno clareneg
seri u t qeaeedhcro trclueovsel -, hsrgtoip hi lr,r ce ee sdaPtnovyicabaJ ttn hosgcniomitatnemelpmi
noital iypbmoc a .tso hekiL lns l oesae ivtbrtlcieae e rhtsnj,ctnmobssoeeiotemhgcdeteelLjpbmoi
Page7
noitu cre ixyeefhit csetpcs enjobiotatneme lspemtiubi r rt. itsneaeIhtt ugbn iiat rneftisotaat nyibam
ssctin tehsmci eirdrheniwtau cqyaearrmah cneht deeb tginoilrp ux g de.nesihslteucdoerrhopcFs
,elpmaxe nnaoitatne mteclepjmbio yam drocer eht epyt fo elbatucexe ti ,sniatnoc stimuminim
niaat nsitacm esj s b.as,o c lcefteCidoehtotsciretca reachncamro f,rsetpnemeri ueqneir htceagmrat
etelpmo ctsil fo ylbisso py( rn)eo tvientle abr staeetntftcepfaemeiijecdrblcpopaomri prpoafrieht
.secnats nniehW eht ssalc ro( st ignilud e)htcnseg astceles a tsoh n odintaatnem erlopfmitcejbo
,noit atsvitic temclea ehdstesab n ose teuhb tifrott aeh t,ts o ehechntat sont i,d eet badvniatceaht
noitatnemelpmi .tcejbo enO ylralucitrap lufesu tcepsa fo siht si taht snoisrev fo aralucitrap
,nru tn i,sih T.tcejb ossal celgni s ay bdegana me bna c,smroftal pf oyteira v an odelipmo c,margorp
elpit leugma ngoantmi vtauhoh tsimwroft ayfltope itn rcoaaev jrbio eehttuc erox ete esshuwtolla
seiranib yb ,dna hdae tgsnniiwo lnloaigeL y loltac ittcaemloetsua e hnto ittcaetrnreomrceolfpmi
.mroftalp taht
neohiTtat nsetmceeljpb moeyidtiivloirbpisnet xygebnital ,uy”scspanagoceinlte“acilppa
, yretore dctasnoenr uoc jit.aigbie gnobryeiraBLkawaa m -h snce noirtoihaoigwnteaLc i,l.pep.ai
noi gee tLnuabci rdtn saei gdnaon iasttmsaaohcrtic la epshpnnta oo!iidttiac rtefgnloelmoeClpmi
stcejbo dna rieht detaicossa ssalc tcejbo wolla noigeL sresu ot nur snoitacilp pnaettirw niyna
gnimmargorp ,egaugnal gnisu yna gnimmargorp ,mgidarap no yna lanoitatupmo cecruoserrof
.elbatucexe na sah resu eht hcihw
nsoeihtcaatCn e4m.e4lpmI
noitatnemelpmI sehcac diova egarots dna noitacinummoc stsoc yb gnirots snoitatnemelpmirof
retal .esuer ehT ecafretni ot eht noitatnemelpmi ehcac tcejbo si detciped ni erugiF a—5elgnis
dohtem si dedivorp ot nruter eht htap fo a lacol elif gniniatnoc a nevig noitatnemelpmis’tcejbo
data. Host objects, rather than downloading implementations themselves, invoke
class ImplementationCache {
pathName getImplementation(LOID impl);
};
FIGURE 5. The Legion implementation cache interface
)(noitatnemelpmIteg no rieht lacol noitatnemelpmi ehcac .tcejbo ehT ehcac tcejborehtie
sdnif ti ydaerla sah a dehcac ypoc fo eht noitatnemelpmi ro ti sdaolnwod dna sehcac a wen.ypoc
nI rehtie ,esac eht ehcac tcejbo snruter eht s’elbatucexe htap ot eht .tsoh nI smret fo,ecnamrofrep
using a cached binary results in object activation being almost as inexpensive as running a
.mmmao err letgfaalsociyrofspl
ruO noitatnemelp mliedom sekam eht noitadilavni fo dehcac seiranib a laivirt.melborp
ecniS ssalc stcej byoficeps eht DIOL fo n oeihttatneme loptmi esu no hc aneoit a,vtistecuaqera
ssalc deen ylno egnahc sti tsil fo seiranib ot ecalper eht noi tdalto nDeImOeLlpm ihtiw ehtwen
noitatne m, des enltdhapsltmeo iunqoeirtav ietr cuhdatteuiif w flni l oce i.ie bewespwhnrseToenv
.sehcac morf dedracsid eb nac dna tuo-emit lliw ,desu eb regnol on ylpmis lliw
gs5nt.in4dengiAB
gnidniB stnega era stcejbo hcihw etatilicaf eht noitalsnart fo seman )sDIOL( morfs’noigeL
,labolg ediw-dirg ecapseman ot lautca sesserdda elbasu yb tropsnart .slocotorp gnidniB ,stnegani
,trap tnemelpmi ycnerapsnart-noitacol ni dirg .gnitupmoc sihT melborp si desserdda ni eht
ASGO ni eht RSG-ot-HSG gnippam .]01[ A gnidnib tnega si yllaitnesse a ehcac fo DIOLot
tcejbo sserdda )AO( sgnippam taht si derahs yb lla fo sti .stneilc hguohtlA yreve noigeLtcejbo
Page8
sah a ehcac fo sgnidnib rof rehto noigeL ,stcejbo eht gnidnib tnega stcartsba yawa eht
msinahcem rof gninimreted a eellac s’tcejbo lautca sserdda fi ti si ton ni eht s’rellaclanretni
cache. While details of the Legion’s naming and binding mechanisms are provided in section
,1.Section5 re6ugiF swohs eht ecafretni rof gnidnib .stnega ehT getBinding(LOID)
noitcnuf snruter a gnidnib rof a deificeps ,DIOL dna getClassBinding(LOID) snrutera
gnidnib rof eht ssalc tcejbo fo eht tcejbo htiw a nevig ;DIOL htob era dednetni ot ebdekovni
directly by a client object that is in search of a binding. The )gnidniB(gnidniBteg dna
)gnidniB(gnidniBssalCteg sdohtem troppus eht gnidniber ,msinahcem hcihw swollaa
tneilc ot ssap ni a elats gnidnib .e.i( eno rof na tcejbo taht sah detargim ro emoceb )trenidna
stcerid eht gnidnib tnega ot teg a wen .gnidnib ehT addBinding(Binding) dna
)DIOL(gnidniBevomer functions allow a binding agent to act as a database of bindings
rednu eht lortnoc fo lanretxe .stcejbo A ssalc nac esu )DIOL(gnidniBevomer ot evomerna
s'ecnatsni gnidnib nehw taht ecnatsni semoceb treni ro steg ,deteled dna nac llac
)gnidniB(gnidniBdda instance.an of migration or activcarteiaotni,o n, upon
class BindingAgent {
Binding getBinding(LOID object);
Binding getBinding(Binding stale_binding);
Binding getClassBinding(LOID object);
Binding getClassBinding(Binding stale_binding);
int addBinding(Binding new_binding);
int removeBinding(LOID object);
;}
FIGURE 6. The Legion binding agent interface
gn in dofeniohittbu ctecxee ryrerrohoaftcss e,cgennik ayelptsc i ,rsetttros nangengiadniB
, s esstcetnnccei oeisnrjlapbc coeka me he tcenmea us fqdoe osshlt leeamn ciomtr. egatneiddnib
,revewoH ni redro ot ekam eht gnidn imbsinah ceelmbalacs ot a yrev egral rebmun fo,stcejbo
gnidnib stnega era yrassecen ot etubirtsid eht gnidnib daol dna diova .stops-toh oTevorpmi
, ygtni ilsditnbniaeblga acnsac d eerbugi feonttoacr ehptoiowc e nroehton aot evr ers.isethnteilc
roF ,ecnatsni yeht nac eb dezina g,ryollacihcrareih ekil SND eman ,srevres ro nac etalumea
sgnidn igbnidivo rrp oyftilibisnops eer h fteom ogsnida ofl fyobere h,t]9 3e[e rgtninibm oecrawtfos
.sessalc morf yawa
smsinah cneoMi g ye.eL5K
eW evah nees woh sresu nac etaerc stcejbo taht ekam etis ro ecruoser cificeps ycilopsnoisiced
gnisu s’noigeL .sessalc ehT noitcaretni fo spuorg fo noigeL stcejbo taht ekam pu a noigeLdirg
implement various Legion mechanisms that other objects can use. These mechanisms include
smsinahcem rof labolg ,gnidnib/gniman ,gniludehcs tluaf ecnarelot dna .ytiruces hcaE si
discussed.is autonomy and extensibility on impact its and below briefly described
ggn ni1did.nmn5aaiNB
noigeL stcejbo era deifitnedi hguorht a level-eerht gniman ,yhcrareih detciped ni erugiF .7 tAeht
highest level, objects are identified by user-defined text strings called txetnocseman . These user-
level txetnoc seman era deppam yb a yrotcerid ecivres dellac txetnocecaps to unique location-
independent system-level names called noigeL tcejbosreifitnedi ( LOID .)s roF tcerid-ot-tcejbo
object communication, LOIDs must be bound to low-level tcejbo sesserdda ( sAO ) that are
meaningful within the context of the transport protocol used for communication. The process by
hci hswDIOL er adeppam o t stecsesjebr odsdi adella ceh tnoigeL gnidnisbsecorp (see Figure 7).
Page9