Kynot Spch Collaborativ s and Pr-to-Pr Grids Goffry ox 1,2,4, Hasan Bulut 2, Kangsok Kim 2, Sung-Hoon Ko 1, Sangmi L 5, Sangyoon h 2, Shridp Pallickara 1, Xiaohong Qiu 1,3, Ahmt yar 1,3, Minjun Wang 1,3, Wnjun Wu 1 1 Community Grid Computing Laboratory, ndiana nivrsity 501 N Morton Suit 224, Bloomington N 47404 2 Computr Scinc Dpartmnt, ndiana nivrsity 3 EECS Dpartmnt, Syracus nivrsity 4 School of nformatics and Physics Dpartmnt, ndiana nivrsity 5 Computr Scinc Dpartmnt lorida Stat nivrsity gcf@indiana.du,hbulut@cs.indiana.du, kakim@cs.indiana.du shko@grids.ucs.indiana.du, sl@grids.ucs.indiana.du, ohsangy@cs.indiana.du, spallick@indiana.du, xiqiu@syr.du, auyar@syr.du, mwang03@syr.du, wwu@indiana.du Abstract W dfin Pr-to-Pr Grids built around intgration of tchnologis from th pr-to-pr and grid filds. Grids provid robust largly asynchronous shard rsourcs for virtual organizations. W show how on can xtnd this to synchronous collaboration with a common pr-to-pr Grid architctur. Two building blocks ar a common dynamic mssaging nvironmnt and systmatic us of s including on to support sssion spcification and control. W prsnt our prototyp audio-vido confrncing and mssaging nvironmnt NaradaBrokring. W dscrib a cor collaboration dfind with an XML protocol XGSP subsuming th capabilitis of H323, SP and JXTA. 1 Pr-to-Pr Grids Thr ar no crisp dfinitions of Grids [1,2] and Pr-to-Pr (P2P) Ntworks [3] that allow us to unambiguously discuss thir diffrncs and similaritis and what it mans to intgrat thm. Howvr ths two concpts conjur up strotyp imags that can b compard. Taking xtrm cass, Grids ar xmplifid by th infrastructur usd to allow samlss accss to suprcomputrs and thir datasts. P2P tchnology is xmplifid by Napstr and Gnutlla, which can nabl ad hoc communitis of low-nd clints to advrtis and accss th fils on th communal computrs. Each of ths xampls offrs srvics but thy diffr in thir functionality and styl of implmntation. Th P2P xampl could involv srvics to st-up and join pr groups, brows and accss fils on a pr, or possibly to advrtis on s intrst in a particular fil. Th classic grid could support job submittal and status srvics and accss to sophisticatd data managmnt systms. Grids typically hav structurd robust scurity srvics whil P2P ntworks can xhibit mor intuitiv trust mchanisms rminiscnt of th ral world. Again Grids typically offr robust srvics that scal wll in pr-xisting hirarchically arrangd organizations; P2P ntworks ar oftn usd whn a bst ffort srvic is ndd in a dynamic poorly structurd community. f on nds a particular hot digital rcording, it is not ncssary to locat all sourcs of this; a P2P ntwork nds to sarch nough plausibl rsourcs that succss is statistically guarantd. n th othr hand, a 3D simulation of th univrs might nd to b carfully schduld and submittd in a guarantd fashion to on of th handful of availabl suprcomputrs that can support it. Databas acing ntrfacs Mssags sr acing ntrfacs Databas ig. 1 Pr-to-Pr Grid of sourcs linkd by mssags n this articl, w us th concpt of a Pr-to-Pr Grid shown in figur 1 with a st of srvics that includ thos of Grids and P2P ntworks and support naturally nvironmnts that hav faturs of both limiting cass. W will us th mrging s modl bing usd in both ntrnt and Grid communitis and dscribd in [4,5,6]. Hr w captur th ssnc [7] of s as using a distributd objct modl with all intrfacs dfind as ports intracting with XML spcifid mssags. 2 Collaboration in P2P Grids Both Grids and P2P ntworks ar associatd with collaborativ nvironmnts. P2P ntworks startd with adhoc communitis such as thos sharing MP3 fils; Grids
support virtual ntrpriss or organizations ths ar unstructurd and structurd socitis rspctivly. At a high lvl collaboration involvs sharing and in our contxt this is sharing of s, objcts or rsourcs. Ths last thr concpts ar in principl ssntially th sam thing although today sharing lgacy applications lik Microsoft Word is not so asily considrd as sharing srvics. Nvrthlss w can xpct that intrfacs to vrything will vntually b availabl and will tak this point of viw blow whr Word, a Pag, a computr visualization or th audio-vido (at say 30 frams pr scond) from som vido-confrncing systm will all b viwd as objcts or rsourcs with a known srvic intrfac. Thr ar many styls and approachs to collaboration. n asynchronous collaboration, diffrnt mmbrs of a community accss th sam rsourc; th has rvolutionizd asynchronous collaboration with in its simplst form, on mmbr posting or updating a wb pag, and othrs accssing it. Asynchronous collaboration has no spcial tim constraint and typically ach community mmbr can accss th rsourc in thir own fashion; objcts ar oftn shard in a coars grain fashion with a shard L pointing to a larg amount of information. Asynchronous collaboration is quit fault-tolrant as ach usr can manag thir accss to th rsourc and indpndntly accommodat difficultis such as poor ntwork connctivity; furthr wll-stablishd caching tchniqus can usually b usd to improv accss prformanc as th rsourc is not xpctd to chang rapidly. Synchronous collaboration is at a high lvl no diffrnt from th asynchronous cas xcpt that th sharing of information is don in ral-tim. Th ral-tim constraint implis dlays of around 10-1000 msc. pr participant or rathr jittr in transit dlays of a fw mscs. Not ths timing can b compard to th scond or so it taks a browsr to load a nw pag; th svral sconds it taks a lcturr to gathr thoughts at th start of a nw topic (nw PowrPoint slid); and th 30 msc. fram siz natural in audio/vido transmission. Ths numbrs ar much longr than th paralll computing MP mssag latncy masurd in microscond(s) and vn th 0.5-3 msc. typical latncy of a middl-tir brokr. W xploit this obsrvation in sction 5 to build powrful mssaging subsystms at th cost of such middlwar brokr ovrhad. Nvrthlss synchronous collaboration is much hardr than th asynchronous cas for svral rasons. [8,9] Th currnt ntrnt has no rliabl quality of srvic and so it hard to accommodat problms coming from unrliabl ntworks and clints. f your workstation crashs during a an asynchronous accss, on just nds to rboot and rstart on s viwing at th point of intrruption; unfortunatly in th synchronous cas, aftr rcovring from an rror, on cannot rsum whr on lost contact bcaus th rst of th collaborators hav movd on. urthr synchronizing objcts among th community must oftn b don at a fin grain siz. or asynchronous ducation, th tachr can shar a complt lctur whras in a synchronous sssion w might wish to shar a givn pag in a lcturr with a particular scrolling distanc and particular highlighting. n summary synchronous and asynchronous collaboration both involv objct sharing but th formr is fault snsitiv, has modst ral-tim constraints and rquirs fin grain objct stat synchronization. Th application of collaboration in rsarch and ducation is discussd in rfs. [10] and [11] rspctivly. Th sharing mchanism can b roughly th sam for both synchronous and asynchronous cas. n nds to stablish communitis (pr groups) by ithr dirct (mmbrs join a sssion) or indirct (mmbrs xprss intrst in topics and ar givn opportunity to satisfy this intrst). Th indirct mchanism is most powrful and is familiar in P2P systms with JXTA [12] using XML xprssd advrtismnts to link togthr thos intrstd in a particular topic. Audio-vido confrncing systms typically hav a dirct mthod with prhaps mail usd to alrt potntial attnds of an upcoming sssion. Commrcial wb-confrncing systms lik Ex [13] and Placwar [14] us this approach. n asynchronous collaboration, on typically just has notification mchanisms for objct availability and updat. Howvr such sharing nvironmnts do not usually support th microscopic vnts as say on usr dits a fil; rathr major vnts (chck-in and chck-out) ar communicatd btwn participants. Nvrthlss synchronous and asynchronous collaboration can b supportd by variants of th sam publish-subscrib mssaging tchnology of th typ dscribd in sction 5. Collaboration involvs multipl capabilitis which w now discuss in a s or Grid framwork. 1. Mchanism to st up mmbrs (popl, dvics) of a "collaborativ sssions" and thir proprtis 2. Gnric shard tools such as txt chat, whit boards, and audio-vido confrncing 3. Shard applications such as Pags, PowrPoint, and scintific visualization n sction 3, w dscrib th first itm as a "Collaboration as a srvic" which is currntly st using standards lik H323 SP or JXTA. Th last two catgoris in th list abov can b viwd as "just shard objcts" whr objcts could b s but typically ar not at th momnt. n sction 4, w suppos that w can port all objcts to s and dscrib how on can build a gnral approach for making such srvics collaborativ. This givs us "Collaborativ s" with on xampl -- audio-vido confrncing -- givn in sction 3.
3 Collaboration as a Hr w also discuss audio-vido (A/V) confrncing as a bcaus th two bst known sssion spcification standards SP and H323 ar associatd with this application. W hav [15,16] dfind an XML spcification XGSP dfining sssion information for both gnral collaborations and th A/V subsystm. This dscribs rgistration, sssion paramtrs, sssion mmbrship, ngotiation (of for instanc common codcs) and linkag of clints to mdia srvrs. XGSP Collaboration Srvr Sssion Srvr Mdia Srvr NaradaBrokring Mssaging ig. 2 ntgration of multipl A/V subsystms using XGSP igur 2 shows our prototyp with multipl clints th Accss Grid from Argonn [17], a typical H323 clint (such as a commrcial Polycom systm [18]) and on using a nativ XGSP framwork, introprating. Thr is th spcializd A/V application mdia srvr and th gnral sssion srvr with a wb intrfac. W dscrib th mssaging nvironmnt NaradaBrokring in sction 5. 4 Collaborativ s DL Application or Contnt sourc XGSP Clint H323 Clint Accss Grid Clint n ordr to dscrib a gnral approach [19] to collaboration, w nd to assum that vry srvic has on or mor ports in ach of catgoris shown in fig. 3. W xploit th fact that th stat and rsults of ach srvic is ntirly dfind by mssags on ths ports. Th first catgory ar (rsourc-facing) ports which supply th information ndd to dfin th stat of th srvic; G a t w a y sourc acing sr acing Ports dfining nput (Control) and utput Ports ig. 3 sr and sourc acing Ports of a ths may b augmntd by usr-facing input port(s) that allow control information to b passd by th usr. Th final catgory is formd by usr-facing output ports that supply information ndd to construct th usr intrfac. Asynchronous collaboration can shar th data (.g. L for a pag or body of an mail mssag) ndd to dfin a srvic (display pag or brows -mail in xampls). bjct r Lt us now considr synchronous collaboration. f on xamins an objct, thn thr is typically som piplin as sn in fig. 4 from th original objct to th vntual displayd usr intrfac; w hr assum that ach stag of th piplin is a srvic with data flowing from on to anothr. athr than a simpl piplin, on can hav a complx dynamic graph linking srvics togthr but this dos not chang this discussion. Not that such a piplin is natural to support not only ndd transformations but also modrn portal architcturs [20, 21] whr on stag in th piplin corrsponds to th aggrgation shown in fig. 5. bjct r DL Application or Contnt sourc bjct r thr thr sr acing Ports bjct r ig. 4 Typical Piplin btwn srvics Portal Aggrgat -sr acing ragmnts bjct r ndr ig. 5 sr acing Ports and Aggrgation Portals n can gt diffrnt typs of sharing dpnding on which viw of th basic objct on shars i.. on whr on intrcpts th piplin and shars th flow of information aftr this intrcption. W can idntify thr particularly important cass illustratd in figurs 6, 7 and 8; ths ar shard display, shard input port and shard usrfacing output port. Th shard input port cas is usually calld shard vnt but in fact in a modrn architctur with all rsourcs communicating by mssags, all collaboration mods can b implmntd with a similar vnt mchanism dscribd in sction 5. n ach collaboration mod w assum thr is a singl mastr clint which controls th srvic; on can in fact hav much mor complx scnarios with simultanous and intrchangabl control. Howvr in all cass, thr is
bjct r bjct r bjct r Shard Evnt (Mssag) bjct r ig. 6 Shard Collaboration Mod Mastr bjct r thr Participants instantanously on mastr and on must transmit th stat as sn by this systm to all othr participants. n shard display modl of fig. 6, on shars th bitmap (vctor) display and th stat is maintaind btwn th clints by transmitting (with suitabl comprssion) th changs in th display. As with vido comprssion lik MPEG, on uss multipl vnt typs with som dfining full display and othrs just giving updats. bviously th complt display rquirs substantial ntwork bandwidth but it is usful vry now and thn so that on can support clints joining throughout sssion, has mor fault tolranc and can dfin full display updat points (major vnts) whr asynchronous clints can join a rcording. Supporting htrognous clints rquirs that sophisticatd shard display nvironmnts automatically chang siz and color rsolution to suit ach community mmbr. Shard display has on ky advantag it can immdiatly b applid to all shard objcts; it has two obvious disadvantags it is rathr difficult to customiz and rquirs substantial ntwork bandwidth. Shard nput Port (plicatd ) Collaboration Evnt (Mssag) Srvic Srvic Srvic Mastr ig. 7 Shard nput Port Modl for Collaborativ s Collaboration as a St up Sssion with XGSP thr Participants n th shard input port (or input mssag) modl of fig. 7, on rplicats th srvic to b shard with on copy for ach clint. Thn sharing is achivd by intrcpting th piplin bfor th mastr wb srvic and dircting copis of th mssags on ach input port of th mastr srvic to th rplicatd copis. nly th usr-facing ports in this modl ar typically partially shard with data from th mastr transmittd to ach rplicatd srvic but in a way that can b ovrriddn on ach clint. W can illustrat this with a mor familiar PowrPoint xampl. Hr all th clints hav a copy of th PowrPoint application and th prsntation to b shard. n th mastr clint, on uss som sort of CM wrappr to dtct PowrPoint chang vnts such as slid and animation changs. Ths chang vnts ar snt to all participating clints. This modl isn t usually phrasd as shard input ports but that s just bcaus PowrPoint as currntly shippd is not st up as a srvic with a mssaging intrfac. n can build a similar shard browsr and for som browsrs (such as that for SVG from Apach) on can in fact dirctly implmnt th srvic modl. [22-24] Thr is a variant hr as on can ithr trap intrnal vnts (such as slid changs in PowrPoint or txtaras changs in a browsr) or th xtrnal mous and kyboard vnts that gnratd thm. W onc dvlopd a sophisticatd shard browsr using th JavaScript vnt modl to trap usr input to a browsr. Ths vnts wr transmittd dirctly to participating clints to implmnt such a shard input port modl with th usr intrfac playing th rol of input ports. W can hop that dvlopmnts [25] such as P and A ( srvics for mot Portals and ntractiv Applications) will dfin usr-facing mssag ports and th intractions of srvics with input dvics so that a cohrnt systmatic approach can b givn for rplicatd srvics with shard input ports. Shard utput Port Collaboration Mssag ntrcptor DL Application or Contnt sourc Evnt (Mssag) Collaboration as a St up Sssion with XGSP Mastr thr Participants ig. 8 Shard utput Port Modl for a Collaborativ
Th shard output port modl of fig 8 only involvs a singl srvic with usr-facing ports giving a mssaging intrfac to th clint. As in th nxt sction and fig. 5, a portal could manag ths usr-facing ports. As (by dfinition) th usr-facing ports of a srvic dfin th usr intrfac, this mchanism simply givs a collaborativ vrsion of any srvic. n simpl xampl can b built around any contnt or multi-mdia srvr with multi-cast output stram(s). This mthod naturally givs, lik shard display, an idntical viw for ach usr but with th advantag of typically lss ntwork bandwidth sinc th bitmap display usually is mor voluminous than th data transmittd to th clint to dfin th display. Elswhr [19, 22, 23], w discuss usr intrfacs and suggst that th usr facing ports should not dirctly dfin th intrfac but a mnu allowing th clint to choos th intrfac styl. n such a cas, on can obtain from th shard usr-facing modl, collaborativ viws that ar customizd for ach usr. f cours th rplicatd srvic modl of fig. 7 offrs vn gratr customizability as ach clint has th frdom to accpt or rjct data dfining th shard srvic. Hr w hav discussd how to mak gnral applications collaborativ. igs. 7 and 8 also us th (XGSP-basd) cor collaboration wb srvic introducd in sction 3 [15,16] with ports allowing sssions to b dfind and to intract with th vnt srvic. This collaboration wb srvic can support both asynchronous and all mods of synchronous collaboration. 5 NaradaBrokring Mssag W hav dsignd and implmntd a systm NaradaBrokring [26-28] supporting th mssaging ndd in a Pr-to-Pr Grid with a dynamic collction of brokrs supporting a gnralizd publish-subscrib mchanism. outing 1 DL Ports Abstract Application ntrfac Dstination Sourc Matching sr Profils And Customization (Virtual) Quu Mssag or Evnt Brokr Mssag Systm ntrfac iltr 2 workflow DL Ports Abstract Application ntrfac ig. 9 Architctur of NaradaBrokring Mssag/Evnt Sric This systm intrcpts all mssags and provids capabilitis that can b prformd at th mssag lvl indpndnt of th th dtails of th srvics gnrating th mssags. Th routing includs dynamic protocol choic and tunnling through firwalls to provid optimizd transport subjct to application-lvl quality of srvic rquirmnts. t supports TCP,DP, multicast, SSL and TP. NaradaBrokring braks a givn mssag transmission into links (ach btwn NaradaBrokring nods) and attmpts to us th most appropriat protocol on ach link using a built-in prformanc monitoring srvic. As dscribd lswhr [5,6,19, 26-28] this can oprat ithr in a clint-srvr mod lik JMS (th Java Mssag [29]) or in a compltly distributd JXTA-lik prto-pr mod. By combining ths two disparat modls, NaradaBrokring can allow optimizd prformancfunctionality trad-offs for diffrnt scnarios. Not as mntiond arlir, that typical ovrhads for brokr procssing ar around on milliscond. This is accptabl for ral-tim collaboration [16] and vn audio-vido confrncing whr ach fram taks around 30 millisconds. W hav dmonstratd that such a gnral mssaging systm can b applid to ral-tim synchronous collaboration using th commrcial Anabas infrastructur [30]. Th Anabas systm uss JMS to handl all collaboration mods and w hav succssfully usd NaradaBrokring to rplac JMS in this cas. Thus in collaboration, NaradaBrokring provids th appropriat (softwar controlld multicast) linkag btwn sssion participants and furthr cops with firwalls and othr transport link issus. n th cas of slow links such as dial-up links and handhld clints, NaradaBrokring supports filtring of th mssags to chang formats such as rducing rsolution of an imag or choosing a mor compact codc for audio-vido mssags. W hav built all protocol s into NaradaBrokring so that can b usd in all collaboration applications including thos nding DP and TCP/P Acknowldgmnts This publication mad possibl through partial support providd by DoD High Prformanc Computing Modrnization Program (HPCMP) Programming Environmnt & Training (PET) activitis through Mississippi Stat nivrsity undr th trms of Agrmnt No. # GS04T01BC0060. Th nivrsity of llinois also providd support through th PAC Partnrs program fundd by NS. Th opinions xprssd hrin ar thos of th authors and do not ncssarily rflct th viws of th sponsors. frncs 1. Th Grid orum http://www.gridforum.org 2. Globus Grid Projct http://www.globus.org
3. Pr-To-Pr: Harnssing th Bnfits of a Disruptiv Tchnology, ditd by Andy ram, illy Prss March 2001. 4. ran Brman, Goffry ox and Tony Hy, Grid Computing: Making th Global nfrastructur a ality, John Wily & Sons Ltd, Chichstr, 2003. S http://www.grid2002.org 5. Hasan Bulut, Goffry ox, Dnnis Gannon, Kangsok Kim, Sung-Hoon Ko, Sangmi L, Sangyoon h, Xi ao, Shridp Pallickara, Quinlin Pi, Marlon Pirc, Alksandr Slominski, Ahmt yar, Wnjun Wu, Choonhan Youn An Architctur for -Scinc and its mplications prsntd at 2002 ntrnational Symposium on Prformanc Evaluation of Computr and Tlcommunication Systms (SPECTS 2002) July 17 2002. http: //grids.ucs.indiana.du/ptliupags/publications/spctss cinc.pdf 6. Goffry ox, zgur Balsoy, Shridp Pallickara, Ahmt yar, Dnnis Gannon, and Alksandr Slominski, "Community Grids" invitd talk at Th 2002 ntrnational Confrnc on Computational Scinc, April 21 -- 24, 2002 Amstrdam, Th Nthrlands. http: //grids.ucs.indiana.du/ptliupags/publications/iccs.pdf 7. s Dscription Languag(DL) vrsion 1.1 http://www.w3.org/t/wsdl 8. Collction of sourcs on distanc ducation by G. ox http: //grids.ucs.indiana.du/ptliupags/publications/distd/. 9. ox, G., Scavo, T., Brnholdt, D., Markowski,., McCrackn, N., Podgorny, M., Mitra, D., and Malluhi, Q., ``Synchronous Larning at a Distanc: Exprincs with TANG ntrativ''. Suprcomputing 98 Confrnc, Novmbr 1998. http://www.oldnpac.org/projcts/training/paprs/sc98/ 10. Goffry ox, Sung-Hoon Ko, Marlon Pirc, zgur Balsoy, Jak Kim, Sangmi L, Kangsok Kim, Sangyoon h, Xi ao, Mustafa Varank, Hasan Bulut, Gurhan Gunduz, Xiaohong Qiu, Shridp Pallickara, Ahmt yar, Choonhan Youn, Grid s for Earthquak Scinc; Concurrncy and Computation: Practic and Exprinc in ACES Spcial ssu, 14, 371-393, 2002. http: //aspn.ucs.indiana.du/gmmauisummr2001/rsourc s/gmandit7.doc 11. Goffry ox, Education and th Entrpris with th Grid, chaptr in rf. 4. 12. Sun Microsystms JXTA Pr to Pr tchnology. http: //www.jxta.org. 13. Ex Collaboration Environmnt. http: //www.wbx.com 14. Placwar Collaboration Environmnt. http: //www.placwar.com 15. Goffry ox, Wnjun Wu, Ahmt yar, Hasan Bulut "A s ramwork for Collaboration and Audio/Vidoconfrncing"; procdings of 2002 ntrnational Confrnc on ntrnt Computing C'02: Las Vgas, SA, Jun 24-27, 2002. http: //grids.ucs.indiana.du/ptliupags/publications/avwbs rvicapril02.pdf 16. Hasan Bulut, Goffry ox, Shridp Pallickara,Ahmt yar and Wnjun Wu, ntgration of NaradaBrokring and Audio/Vido Confrncing as a. http: //grids.ucs.indiana.du/ptliupags/publications/avvr NaradaBrokring.pdf 17. Accss Grid Confrncing Environmnt from Argonn National Laboratory, http://www.accssgrid.org 18. Polycom Confrncing Environmnt http: //www.polycom.com 19. Goffry ox, Dnnis Gannon, Sung-Hoon Ko, Sangmi L, Shridp Pallickara, Marlon Pirc, Xiaohong Qiu, Xi ao, Ahmt yar, Minjun Wang, Wnjun Wu, "Pr-to-Pr Grids", chaptr in rf. 4. 20. Jtspd Portal from Apach http: //jakarta.apach.org/jtspd/sit/indx.html 21..Balsoy,M.S.Aktas,G.Aydin,M.N.Aysan,C. kibas, A. Kaplan, J. Kim, M. E. Pirc, A. E. Topcu, B. Yildiz, and G. C. ox., "Th nlin Knowldg Cntr: Building a Componnt Basd Portal." Procdings of th ntrnational Confrnc on nformation and Knowldg Enginring, 2002. http: //grids.ucs.indiana.du: 9000/slid/ptliu/rsarch/gatway/Paprs/KCPapr.pd f 22. Goffry ox, Sung-Hoon Ko, Kangsok Kim, Sangyoon h, Sangmi L, "ntgration of Hand-Hld Dvics into Collaborativ Environmnts"; procdings of th 2002 ntrnational Confrnc on ntrnt Computing (C-02). Jun 24-27 Las Vgas. http: //grids.ucs.indiana.du/ptliupags/publications/pdagarn tv1.pdf. 23. Sangmi L, Goffry ox, Sunghoon Ko, Minjun Wang, Xiaohong Qiu, "biquitous Accss for Collaborativ nformation Systm using SVG", Procdings of SVGopn confrnc July 2002, Zurich, Switzrland. http: //grids.ucs.indiana.du/ptliupags/projcts/carousl/pap rs/draft.pdf 24. Goffry ox, Sangmi L, Sunghoon Ko, Kangsok Kim, Sangyoon h, "CASEL srvic: nivrsal Accssibl srvic Architctur for Collaborativ Application",Novmbr 2002, http: //grids.ucs.indiana.du/ptliupags/publications/carousl _PrCom03.doc. 25. ASS s for mot Portals (P) and s for ntractiv Applications (A) http: //www.oasis-opn.org/committs/
26. Goffry ox and Shridp Pallickara Th NaradaBrokring Evnt Brokring Systm: vrviw and Extnsions; procdings of th 2002 ntrnational Confrnc on Paralll and Distributd Procssing Tchniqus and Applications (PDPTA'02). http: //grids.ucs.indiana.du/ptliupags/projcts/naradabrok ring/paprs/naradabrokringbrokringsystm.pdf 27. Goffry ox and Shridp Pallickara JMS Complianc in th NaradaBrokring Evnt Brokring Systm to appar in th procdings of th 2002 ntrnational Confrnc on ntrnt Computing (C-02). http: //grids.ucs.indiana.du/ptliupags/projcts/naradabrok ring/paprs/jmssupportnnaradabrokring.pdf 28. Goffry ox, Shridp Pallickara, and Xi ao, "A Scalabl Evnt nfrastructur for Pr to Pr Grids", procdings of 2002 Java Grand/SCPE Confrnc, Sattl, Novmbr 2002, ACM Prss, SBN 1-58113-599-8, pags 66-75. http: //grids.ucs.indiana.du/ptliupags/publications/scalabl EvntArchorP2P.doc 29. Sun Microsystms. Java Mssag.http: //java.sun.com/products/jms 30. Anabas Collaboration Environmnt, http: //www.anabas.com