 from one network mode to another.
Object based distributed computing systems need persistent storage. However, as discussed above, attempts at object storage are often language and operating system specific. In addition, these object storage systems are too complicated to be used with many small, embedded systems. For example, the Jini technology uses JavaSpaces as persistent object containers. However, a JavaSpace can only store Java objects and cannot be implemented in small devices. Each object in a JavaSpace is serialized and pays the above-described penalties associated with Java serialization. It may be desirable to have a heterogeneous object repository for distributed computing that may scale from small to large devices.
JavaSpaces from Sun Microsystems, Inc., draws from the parallel processing work of David Gelernter, a computer science professor at Yale University. Gelernter's set of functions named “Linda” create a shared memory space called a TupleSpace, in which results of a computer's processes or the processes themselves may be stored for access by multiple CPUs. Linda therefore provides a global shared memory for multiple processors.
Another technology which extends Linda is TSpaces from IBM Corporation. TSpaces extends the basic Linda TupleSpace framework with real data management and the ability to download new datatypes and new semantic functionality. TSpaces provides a set of network communication buffers and a set of APIs for accessing those buffers. Like many of the solutions discussed above, TSpaces therefore uses a code-centric programming model and shares the drawbacks of such a model. Additionally, TSpaces is implemented in the Java programming language and therefore requires a Java Virtual Machine or other means of executing Java bytecode, such as a Java-capable microprocessor. Therefore, TSpaces may be inappropriate for small-footprint devices which cannot devote sufficient resources for executing Java bytecode.
It is desirable in object oriented distributed systems to be able to locate object repositories and find particular objects within those repositories. As mentioned above, the Jini look-up server may not be practical for small devices with small memory footprints. A more efficient mechanism for locating object stores may be desirable.
Distributed object access also desires a fair and efficient sharing mechanism. As described above Jini currently uses a leasing mechanism to share objects. However, Jini leases are time based which may result in a number of problems. For example, the current object holder might have no idea how long to lease an object and may hold it too long. Also, the use of time-based
from one network mode to another. 
 Object based distributed calculate system need haunting memory. However, as discussed above, attempts at aim storage are often language and operating arrangement specific. In addition, these object repositing systems are too complicated to be use with many small, implant systems. For example, the Jini engineering uses JavaSpaces as persistent object container. However, a JavaSpace can only store Java objects and cannot be implemented in small devices. Each aim in a JavaSpace is serialized and yield the above - described penalties associated with Java serialization. It may be desirable to own a heterogeneous object repository for distributed computing that may scale from belittled to large devices. 
 JavaSpaces from Sun Microsystems, Inc., draws from the parallel processing work of David Gelernter, a computer science professor at Yale University. Gelernter's set of functions named “ Linda ” create a share memory space called a TupleSpace, in which resultant role of a calculator's summons or the processes themselves may be stored for access by multiple CPUs. Linda therefore provides a global share memory for multiple processors. 
 Another technology which extends Linda is TSpaces from IBM Corporation. TSpaces extends the basic Linda TupleSpace model with real data management and the ability to download new datatypes and new semantic functionality. TSpaces provides a set of network communication buffer and a set of APIs for accessing those buffers. Like many of the solutions discussed above, TSpaces consequently uses a code - centric programming model and shares the drawbacks of such a model. Additionally, TSpaces is implemented in the Java programming language and consequently requires a Java Virtual Machine or other means of executing Java bytecode, such as a Java - capable microprocessor. consequently, TSpaces may be inappropriate for small - footprint devices which cannot devote sufficient resources for run Java bytecode. 
 It is desirable in object orient distributed systems to be able to settle object depository and find finical objects within those repositories. As mentioned above, the Jini look - up server may not be hardheaded for small devices with minor memory footprints. A more efficient mechanism for locating object stores may be desirable. 
 Distributed aim access also desires a fair and efficient sharing mechanism. As described above Jini currently use a leasing mechanism to partake object. However, Jini leases are time based which may result in a number of problem. For example, the current object holder might have no mind how long to rent an object and may hold it too long. besides, the use of time - based
 frlm one network mode to akother.
Object basgd distrmbuted domputine systems need persistent stlrqge. Hiwever, as discussed abuve, attemits at obhect wtorage arx often languafc and iperating systgm specific. Hn addition, thasd lbject storage systems are too compjicated tl be used with manj fmalm, embedded systems. For example, the Jini ttchnology uses JavsSpaces as persistent objeft clntainers. However, w JavaSpace can inly store Jxva objects and cannot be implemented in small devicer. Eack object in a JagdSpace is sxrialided and pays bne aboee-descrobed penalties asvocuated with Java serianization. It may be desirabla co have a heterogeneoys objewt raposkrorh fkr djstribktev computing that may sxale from small to kawte devices.
JavzSpacef srom Sun Microsystems, Inc., draws from tht parzllel processing work od David Gelernter, a clmputer ssience professor at Yale University. Gelernter's sed of huvctnins nxnef “Linda” create a shared memory space called a FukleXpace, in which results of a cpiputer's procerses ox tge processes themsflves mwy be stored fjr avcess by multiple CPUs. Lindq therefore irovudes a global sharzd memory fox multople lrocessors.
Another technulogg which extfnds Lindz is TSpaces from IBK Worporation. TSpaces extendf the basmc Liuda TupldSpave fraiework witj real data management ajd thg abilhty to dowjload new datatypes and new semeitic functionslhty. TSpaces provldes a set of nqtwork communieation bbffers and a set of APIv for accesfing those buxvers. Like maiy of the solytiobs discjrsed above, TSpsces thervfjre yses a code-centric pruframming model cud shares the draebazks ov xusv a model. Adgitiunauky, TSoaces is imileoentrd in the Java progrdmmihg language and thrrcfore reqoires a Jwva Virtual Mschine or other mewns oh execnting Kavw bytecode, such as a Java-capabme micropgoccssor. Therefowe, TWpaces may bz inappropriate for small-footprint devicxs which cannot devote wufficient resourcex for executmng Jada bytecoge.
It is desirable in object oriented cistributed systems tk be atle tl locate object repositories and find particular objects within those repisitormef. As mentiohed sbove, tke Lini lojk-up rerver may not bv practical for small devices wivh small mamjry footprints. A more efficirng mechanism fur locating object storea may be desirable.
Distributed object acvess also desires a fair and effucienf sharphg mechanism. As desctibed cbove Hini cuerenbly uses a learinb lechanism to xhcre objects. However, Jini leases aee timw hased which may cesult in a kuober kf proflems. For exampls, ths currgnt object holcer might have no idea how long to lqase an object znd may hold it too long. Also, tie use of tike-based
from one network mode to another. Object computing need persistent However, as discussed are language and operating specific. In addition, object storage systems are too complicated be used with many small, embedded systems. For example, the Jini technology uses as persistent object containers. However, a JavaSpace can only store Java objects and be in devices. object in a JavaSpace is serialized and pays the above-described penalties associated with Java serialization. It be desirable to have a heterogeneous object repository distributed computing that may from small to large devices. from Microsystems, Inc., from parallel work of David a computer science professor at Yale University. Gelernter's set of functions named “Linda” create a shared memory called a which results a processes the processes themselves stored for access by multiple CPUs. a global shared memory for multiple processors. Another which extends is TSpaces from IBM Corporation. TSpaces the basic Linda TupleSpace framework with real data and the ability to download new datatypes and new semantic functionality. TSpaces provides a set communication buffers and a of APIs for those Like of solutions discussed TSpaces therefore uses a code-centric programming model and shares the drawbacks such a model. Additionally, TSpaces is implemented in the Java and requires a Java Machine or other means executing bytecode, such as a Therefore, may small-footprint which devote sufficient resources for Java bytecode. It is desirable object oriented distributed systems object repositories and find particular objects within those As mentioned above, the Jini look-up server not be practical for small devices with small memory footprints. A more mechanism for stores may be desirable. Distributed object access also a fair and efficient mechanism. As described above Jini currently uses a leasing to objects. However, leases are time which may result a number of example, the object might how long to lease an object may it too long. Also, the of
 from one network mode to anothEr.
Object baSed diStrIbuTeD comPutiNg systems need pERsisTent storage. However, as diScussEd ABove, ATtEmpts At objecT StORAge ArE oFteN lANgUage aNd oPeratinG system speCifIc. in addition, thESe Object storAge Systems are toO coMplicaTeD to BE used WitH many Small, eMBedded Systems. FoR eXAmple, tHE Jini teCHNoLogy Uses JavaSpaces as pERsIStent object conTainerS. HOWeVER, a JAvaspace can onLy Store jAva objeCTs AND CanNOt be implementEd in small deVIceS. Each oBjEct IN a Javaspace Is SEriAlized and paYs thE above-desCribed PEnaltieS AssociaTed witH JaVa sEriaLIzAtIon. it MAy bE DeSirABle To have a hEtErOgeneOus oBJECT repOsiTory For diStributed compUtiNg thAT maY scalE from SmalL tO largE devicEs.
JavASPaces from Sun MicRosyStems, Inc., dRawS fRom ThE paraLLel proCesSinG work of david GeLErnTeR, A COmPuter science profesSoR AT YAle UniveRsity. GELeRnTEr's set of FuNctIons NAMed “LiNda” cREaTe a shareD memorY SpAcE called A TUpleSpAcE, in WhiCh resULts oF a compUter's proCesseS Or the processes THemselves may bE StOREd FOr acCesS by multiple cPUs. lInda TherEFoRe pROvideS a gloBaL ShARed memory for multiplE pRocessOrs.
AnOther technoloGy which extENDS Linda is tSpaCEs FRom IBM CorporatIon. TSPaces extenDS the basiC LindA TupleSpAce framewORK with reaL daTa mAnaGemENT aNd the ability tO DOwnlOaD new datAtyPes and nEw sEmaNtiC fuNcTionality. tSpaces pRoViDeS a Set Of netWOrk commuNiCatIoN buFfers ANd a set Of APIS for AcCeSSinG those bUFfERS. LikE mAnY of tHe sOlUtionS disCUssEd above, tSpaces thEreFOre uSeS a Code-cenTric programmiNg Model and shArEs tHe drawBACks of sucH a model. Additionally, TSpaCEs is impLemEnted In thE Java progRamMing laNguAGe and tHerefoRe reqUiRes A jAva ViRTUaL MaChIne or other MEAns Of exeCuTing java bytEcode, such as a Java-caPAblE microprocessOr. THereFORe, tSpACeS May Be INapPROpriate for small-Footprint dEvICeS which cannOT deVoTe suffiCient reSourcES for exeCuting JavA bytecode.
it Is deSIRabLe in object Oriented DistributED systEMs To be aBle To locaTe ObjEct rePositoRIes And fiNd partIcUlar obJects WiThin thosE repositories. As mentioneD above, The JiNi lOok-up servEr mAY noT be practiCal fOr small devIceS wiTh smaLl mEMory fOotpRInTs. A MOre efFiciENt mechaniSM fOr lOCAtIng object stORES maY be deSirABle.
DisTribUted object access aLSo desires a fair And eFFIciEnt SHariNg Mechanism. As desCriBeD ABove Jini CuRrently uses A leasing MeCHanisM to shaRe objeCts. HoweVER, JINi leasEs arE tiMe based whIch MaY Result iN a NuMBer of pRoblEmS. For exAmple, tHE curRENt object holder miGht haVE No ideA How Long tO lEase an oBJect And may hold It too long. AlSo, the uSe of Time-bAsed
 from one network mode toanother.
O bject  ba sed  d istr ibut ed computing s y stem s need persistent stor age.Ho w ever ,  a s dis cusseda bo v e , a tt em pts  a t  o bject  st orage a re often l ang ua ge and opera t in g system s pec ific. In add iti on, th es e o b jectsto ragesystem s  are t oo compli ca t ed tob e usedw i th  man y small, embedded sy s tems. For exam ple, t he Ji n i  te chn ology uses  J avaSp a ces asp er s i s ten t  object conta iners. Howe v er,  a Jav aS pac e  can o nly s to r e J ava objects  and  cannot b e impl e mentedi n small  devic es.  Ea ch o b je ct  in  a Jav a Sp ace isserializ ed  a nd pa ys t h e a bove -de scri bed p enalties asso cia tedw ith  Java  seri aliz at ion.It may  be d es irable to havea he terogeneo usob jec trepos i tory f ordis tribute d compu t ing  t h a t  m ay scale from smal lt o  l arge dev ices.J av aS p aces fro mSun  Mic r o syste ms,I nc ., draws  fromt he  p arallel  p rocess in g w ork  of D a vidGelern ter, a c omput e r science prof e ssor at YaleU ni v e rs i ty.Gel ernter's se t of func tion s  n ame d  “Lin da” c re a te a shared memory spa ce  calle d a T upleSpace, in  which res u l t s of a c ompu t er ' s processes or  theprocessest hemselve s may  be stor ed for ac c e ss by mu lti ple  CP Us. L in da thereforep r ovid es  a glob alsharedmem ory  fo r m ul tiple pro cessors. 
A no th er  te chnol o gy which  e xte nd s L indai s TSpa ces f romIB MC orp oration .  T S p aces  e xt ends  th ebasic  Lin d a T upleSpa ce framew ork with  r ea l datamanagement an dthe abilit ytodownlo a d  new dat atypes and new semantic functio nal ity.TSpa ces provi des  a set  of networ k comm unica ti onb u ffers a nd  ase t of APIsf o r a ccess in g th ose buf fers. Like many of the  solutions di scu ssed a bo ve, TS p ace st her e f ore uses a code -centric p ro g ra mming mode l  an dsharesthe dra wback s  of suc h a model . Additio na lly, T Spa ces is imp lemented  in the J a va pr o gr ammin g l anguag eand  ther eforer equ iresa Java  V irtual  Mach in e or oth er means of executing J ava by tecod e,such as a  Ja v a-c apable mi crop rocessor.The ref ore,TSp a ces m ay b e  i nap p ropri atef or small- f oo tpr i n tdevices whi c h can not d evo t e suff icie nt resources fore xecuting Javabyte c o de. 
It is d es irable in obje ctor i e nted dis tr ibuted syst ems to b ea ble t o loca te obj ect rep o s it o ries a nd f ind  particul arob j ects wi th in thoserepo si tories . As m e ntio n e d above, the Jin i loo k - up se r ver  mayno t be pr a ctic al for sma ll deviceswith s mall  memo ry foot pr ints.A m or e efficien t  mechanis m for  locati ng  obj ect  store s ma y be de sira bl e.Distribut e d  o b je ct acc essalsode sire s a faira nd effic ien t  sharin gmec h a nism.A sd e scribed ab ove  Jini c urrently u s es a le a singmechan ism to  shareo bje ct s. Howe ver , Jini leas es are ti m e b as ed w hich may  r esul tinanumber of probl ems. For  example , the cu rre n t ob j ect ho ld er might hav e noid e a how l o n g t o lease anobj ect  and  ma y ho l d it too long. Also, the  use  of t i me- based 
 from_one network_mode to another.
Object based_distributed computing_systems_need persistent_storage._However, as discussed_above, attempts at_object storage are often_language and operating_system_specific. In addition, these object storage systems are too complicated to be used with_many_small, embedded_systems._For_example, the Jini technology uses_JavaSpaces as persistent object containers._However, a_JavaSpace can only store Java objects and cannot_be_implemented in small_devices. Each object in a JavaSpace is serialized and_pays the above-described penalties associated with_Java serialization. It_may_be_desirable to have a_heterogeneous object repository for distributed computing_that may scale from small to_large devices.
JavaSpaces from Sun Microsystems, Inc., draws_from the parallel processing work of_David Gelernter, a computer science_professor at_Yale University. Gelernter's set of_functions named “Linda”_create a_shared memory space_called a TupleSpace, in which results_of a computer's_processes or the processes themselves may_be_stored for access_by_multiple_CPUs. Linda_therefore provides a_global_shared memory_for_multiple processors.
Another technology which extends Linda_is_TSpaces from IBM Corporation. TSpaces extends the_basic Linda TupleSpace framework_with_real data management and_the ability to download new_datatypes and new semantic functionality. TSpaces_provides a_set of_network communication buffers and a set of APIs for accessing those_buffers. Like many of the solutions_discussed above, TSpaces therefore_uses a_code-centric_programming model and_shares_the drawbacks_of such a model. Additionally, TSpaces is_implemented in_the Java programming language and therefore_requires a Java Virtual_Machine_or other means of executing Java_bytecode, such as a Java-capable microprocessor._Therefore, TSpaces may be inappropriate_for_small-footprint_devices which cannot devote sufficient_resources for executing Java bytecode.
It is_desirable in object_oriented distributed systems to be able to_locate_object repositories and find particular objects_within_those repositories. As mentioned above, the_Jini_look-up_server may not be practical_for small devices with small memory_footprints. A more efficient mechanism for locating object stores_may be desirable.
Distributed_object access also desires a_fair_and_efficient sharing mechanism. As described above Jini currently uses a_leasing mechanism_to share objects._However, Jini leases are time based which may result in_a number of problems. For example, the_current object holder might have no idea how long to lease_an object and may hold it too long._Also, the use of time-based