| OCR Text |
Show 20 Orion supports a model in whicb there is a shared database, along with a number of private databases . Data can be moved to and from the shared database by a user . Based on duration , Orion bas two kinds of transactions, short and lmuJ. Shod tra.JJSdctioJJS <tre atun1ic. inclept-'JJcle nt , and (L!'<-' seria li zed on <"Xf'CJ iti on. Louq t r<t.Usddium; upcr·a.te un <L priva.lc' daL<t.bdse. star t ing the moment obj ect.s are c!Jeck(·d-ouL from the shared ci<-~.ta b ase and end ing wh e 11 th ey are ch ec ked-in. Orion also Sllpports the notion of a bypotb et ical transaction which lets a user experiment with complex changes without a.flecting tbe d atabase. Orion bas elaborate lock mancLgement and provides flve kinds of locks: S, IS , X, IX , SIX (same as in ESM). It allows both in stance level and class level locking. lu stauces can lw locked inS or X mode whereas classes can be locked in all modes. \Vlw11 a c lass is lo cked, a ll its in stances are locked in the same mode. Orion queues al l lock requests. It allows class lattice locking in which lo cks acquired on a class may he propagated clown t he inh e ritance hierarchy. It supports multiple concurrent Ll'an sactiuns by several cl ien ts hut it seri a lizes them . Orion suppo rts tlw uutiuu of VP rsionable obj ects wl1icb when clwcked out itJLu d p1iv;tl.e cld.La,base , 1(-'ave a par·enL vc·r :o; ion for other users in tiH~ shared database. lt Sitpports tl1rce Lyj)es of versions: 1. Transient -A design that is being worked on . ·) vVorking -- A des ign that has reaclwd a stable state. :L Released -- The final des ign stale that cau be shared with other use rs. ()riuu 11<-~ ::i a clistrilJltLccl arcbite ct un~. T'bis !lleans that the cl a.ta is managed by rnorc tl1 an one rwde ou the network such tl1at the physi cal pla.cemeut of the data ic; transparent to the ttse rs. Orion h;t.s its own qlJcry language. Tbe scope of a qur~ry can be a p rivate d a i dh <tse. tlw ,-.; !J a J·cd daLlhase or hot h. |
