▁in ▁data ▁gr ids . ▁Each ▁topology ▁has ▁a ▁specific ▁purpose ▁in ▁mind ▁for ▁where ▁it ▁will ▁be ▁best ▁util ized . ▁Each ▁of ▁these ▁top ologies ▁is ▁further ▁explained ▁below . ▁ ▁Federation ▁topology ▁is ▁the ▁choice ▁for ▁institutions ▁that ▁wish ▁to ▁share ▁data ▁from ▁already ▁existing ▁systems . ▁It ▁allows ▁each ▁institution ▁control ▁over ▁their ▁data . ▁When ▁an ▁institution ▁with ▁proper ▁authorization ▁requests ▁data ▁from ▁another ▁institution ▁it ▁is ▁up ▁to ▁the ▁institution ▁receiving ▁the ▁request ▁to ▁determine ▁if ▁the ▁data ▁will ▁go ▁to ▁the ▁request ing ▁institution . ▁The ▁feder ation ▁can ▁be ▁lo os ely ▁integrated ▁between ▁institutions , ▁tight ly ▁integrated ▁or ▁a ▁combination ▁of ▁both . ▁ ▁Mon adic ▁topology ▁has ▁a ▁central ▁repository ▁that ▁all ▁collected ▁data ▁is ▁fed ▁into . ▁The ▁central ▁repository ▁then ▁respond s ▁to ▁all ▁queries ▁for ▁data . ▁There ▁are ▁no ▁rep lic as ▁in ▁this ▁topology ▁as ▁compared ▁to ▁others . ▁Data ▁is ▁only ▁accessed ▁from ▁the ▁central ▁repository ▁which ▁could ▁be ▁by ▁way ▁of ▁a ▁web ▁portal . ▁One ▁project ▁that ▁uses ▁this ▁data ▁grid ▁topology ▁is ▁the ▁ ▁Network ▁for ▁Earth qu ake ▁Engineering ▁Sim ulation ▁( NE ES ) ▁in ▁the ▁United ▁States . ▁This ▁works ▁well ▁when ▁all ▁access ▁to ▁the ▁data ▁is ▁local ▁or ▁within ▁a ▁single ▁region ▁with ▁high ▁speed ▁connect ivity . ▁ ▁Hier arch ical ▁topology ▁l ends ▁itself ▁to ▁collaboration ▁where ▁there ▁is ▁a ▁single ▁source ▁for ▁the ▁data ▁and ▁it ▁needs ▁to ▁be ▁distributed ▁to ▁multiple ▁locations ▁around ▁the