JXTA and Web Services and MessagesJXTA and GridsDifferent Web Service OrganizationsPeer to Peer GridRole of Event/Message BrokersNaradaBrokering implements an Event Web ServiceEngineering Issues Addressed by Event / Messaging ServiceFeatures of Event Service IFeatures of Event Web Service IIFeatures of Event Web Service IIISingle Server P2P IllusionNarada Broker NetworkNaradaBrokering and JMS (Java Message Service)Narada/JXTA EventNaradaBrokering and JXTAJXTA just got slowerPDA Collaboration Event FilterSlide 18Slide 19Web Service Architecture for Audio Video ConferencingXGSP: IntroductionXGSP: ExampleNaradaBrokering Futures01/17/1901/17/19uri="http://www.naradabrokering.org" emuri="http://www.naradabrokering.org" email="[email protected]"ail="[email protected]"11JXTA and Web Services and MessagesPTLIU Laboratory for Community GridsGeoffrey Fox, Shrideep PallickaraComputer Science, Informatics, PhysicsIndiana University, Bloomington IN 47404http://www.naradabrokering.orghttp://grids.ucs.indiana.edu/ptliupages [email protected] Edinburgh July 23 200201/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"22JXTA and GridsJXTA and Grid architectures can be implemented as Web Services interacting with (XML-based) messagesWe built a “Grid Messaging System” NaradaBrokering that implements generalized publish-subscribe mechanism in a network of “brokers/routers/rendezvous peers”Narada can replace Java Message Service – Grid-like system•Used to run our synchronous collaboration system Garnet supporting shared display, text chats, Jabber instant messenger ….Narada is integrated with JXTA (as a proxy to rendezvous peers) and can provide reliable messaging between peer groups (and inside?)We are building Collaboration (shared application and audio-video conferencing) as a Web Service•XGSP (XML General Session Protocol) is meant to include H323 SIP and (later) JXTA sessions (peer groups)•JXTA will be able to invoke Access Grid, Polycom, Shared Display sessions01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"33Different Web Service OrganizationsEverything is a resource implemented as a Web Service, whether it be: •back end supercomputers and a petabyte data•Microsoft PowerPoint and this fileWeb Services communicate by messages …..Grids and Peer to Peer (P2P) networks can be integrated by building both in terms of Web Services with different (or in fact sometimes the same) implementations of core services such as registration, discovery, life-cycle, collaboration and event or message transport …..•Gives a Peer-to-Peer GridNarada is an example of Event or Message Service linking web services together01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"44Peer to Peer GridDatabaseDatabasePeersPeersPeer to Peer GridResource FacingWeb Service InterfacesWeb Service InterfacesEvent/MessageBrokersIntegrate P2Pand Grid/WSEvent/MessageBrokersA democratic organizationUser FacingWeb Service Interfaces01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"55Role of Event/Message BrokersWe will use events and messages interchangeably•An event is a time stamped messageOur systems are built from clients, servers and “event brokers”•These are logical functions – a given computer can have one or more of these functions•In P2P networks, computers typically multifunction; in Grids one tends to have separate function computers•Event Brokers “just” provide message/event services; servers provide traditional distributed object services as Web servicesThere are functionalities that only depend on event itself and perhaps the data format; they do not depend on details of application and can be shared among several applications•NaradaBrokering is designed to provide these functionalities•MPI provided such functionalities for all parallel computing01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"66NaradaBrokering implements an Event Web ServiceFilter is mapping to PDA or slow communication channel (universal access) – see our PDA adaptorWorkflow implements message processRouting illustrated by JXTADestination-Source matching illustrated by JMS using Publish-Subscribe mechanismWeb Service 1(Virtual)QueueWeb Service 2Destination Source MatchingFilterRoutingworkflowWSDLPortsWSDLPortsBroker01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"77Engineering Issues Addressedby Event / Messaging ServiceApplication level Quality of Service – give audio highest priorityTunnel through firewallsFilter messages to slow (collaborative or real time) clientsHardware multicast is erratically implemented (Event service can dynamically use software multicast)Scaling of software multicastElegant implementation of Collaboration in a Groove Networks (done better) styleIntegrate synchronous and asynchronous collaboration01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"88Features of Event Service IMPI nowadays aims at a microsecond latencyThe Event Web Service aims at a millisecond latency•Typical distributed system travel times are many milliseconds (to seconds for Geosynchronous satellites)•Different performance/functionality trade-offMessages are not sent directly from P to S but rather from P to Broker B and from Broker B to subscriber S•Actually a network of brokersSynchronous systems: B acts as a real-time router/filterer•Messages can be archived and software multicastAsynchronous systems: B acts as an XML database and workflow engineSubscription is in each case, roughly equivalent to a database query01/17/1901/17/19uri="http://www.naradabrokering.org" email="[email protected]"uri="http://www.naradabrokering.org" email="[email protected]"99Features of Event Web Service IIIn principle Message brokering can be virtual and compiled away in the same way that WSDL ports can be bound in real time to optimal transport