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Collaboration and Web Services

Explore collaborative web services and their benefits for shared displays, replicated services, and more. Learn why web services are ideal for collaboration and the different types of collaboration models. Discover how to make objects collaborative through web services.

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Collaboration and Web Services

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  1. Collaboration and Web Services Geoffrey Fox Professor of Computer Science, Informatics, Physics and Director PTLIU Laboratory for Community Grids Indiana University, Bloomington IN 47404http://grids.ucs.indiana.edu/ptliupages/presentations gcf@indiana.edu uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  2. Collaborative Web Services • First note that there are two distinct concepts • Collaboration as a Web Service • Such as “Audio-Video Conferencing” as a Web Service or “Text Chat as a Web Service” • Collaborative Web Services • Here we view a Web Service as specifying a (distributed) object and wish to share an object • Object could be a Web page, a Job status form, a scientific visualization, a PowerPoint slide etc. (not all of these are Web Services but all should be) uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  3. Why Web Services for Collaboration • Well everything is meant to be a Web Service but also: • Web Services are MUCH EASIER to make collaborative than other objects because all input and output is defined by uniform XML messages • You need to teach your message service about collaboration! • Note local applications are NOT Web Services – input is things like “user mouse click” represented by “method events” (UI program interrupts) not “XML message events” • The elegance of collaborative web services suggest that it could be easiest to make object X (such as PowerPoint or SVG) collaborative not by traditional direct methods but by converting to a Web Service uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  4. Types of Collaboration I • Shared Display: here one shares the rendering of a Web Service. No modification is needed of the web service. Rather this is handled by the portal controlling the user interface • Collaborative Replicated Web Services: here one replicates several instances of a web service and the task is to keep these copies consistent. This synchronizes inputs to multiple Web Services • Collaborative Web Service Access: here one has multiple clients accessing a single instance of a web service and obtaining consistent views. This multicasts output of a single Web service to multiple clients uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  5. Types of Collaboration II • Shared Export is built on synchronizing the viewers (PDF HTML SVG Browsers) of standard formats. It differs from Shared Web Services in that user inputs (mouse clicks, keyboard) and not (XML Web service) messages are shared • One can share export with either a single or replicated back-end engine • The most elegant shared export models are built around viewers of documents sharing W3C DOM • It would be interesting to convert W3C DOM to a Web Service • Shared event is like shared Web service but is a custom “implementation” for each application • One can often choose between sharing user inputs or sharing implied change in specification of object state uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  6. SharedWeb Service SharedDisplay Shared Export Shared Event Object Viewer Object Display Object Object’ Object’’ In these and following diagrams, we havethree collaborating clients; is masterwhile and are non-masters Collaboration: Shared Display • Sharing can be done at any point on “object” pipeline Master Event(Message)Service Object Display Shared Display shares framebuffer with eventscorresponding to changedpixels in master client. Object Display uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  7. SharedWeb Service SharedDisplay Shared Export Shared Event Object Viewer Object Display Collaboration: Shared Export I • Another point on object to display pipeline DrivingAppl. Object Object’ Master Shared Export shares client side viewer with events corresponding to user interactions orinformation from drivingapplication Event(Message)Service Object Viewer Object Display Object Viewer Object Display uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  8. Object Viewer Object Display Collaborative Web Service Access • Web Service either supports collaboration directly or uses event service Web Service InterceptorProviding General Services Set Collaboration Mode Master WebService Object Object Viewer Object Display Web Service has a porton which collaborativemodes set Web Service can be“front-end” (in middletier) to complex back-end object Event(Message)Service Object Viewer Object Display uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  9. Web Service Interceptor • Collaborative Web Services are implemented “just” by replicating the messages that are output by the Web service • This replication is provided by the event service which needs both client and service dependent information • The service specific message function is provided by an interceptor or an adaptor which takes care of issues like security, collaboration, management, service information, which message service to use • The client specific function specifies the client profile telling event service how to filter events for each client • Depending on system implementation, the interceptor is either built into web service or a wrapper provided by event service • The latter implies that all messages between clients and (all) web services are handled by event service • There are ports on the interceptor allowing specification of Collaboration Session and giving event service access to information needed for appropriate filtered (as per profile) message delivery to clients uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  10. Collaborative Web Service Access • This shows how the “Collaboration Web service” supports collaborative web services Web Service InterceptorProviding General Services Collaborationas a WebService Collaborative WebService Set Collaboration and Message Mode MasterClient Web Service has a porton which collaborativemodes set Web Service can be“front-end” (in middletier) to complex back-end object Event(Message)Service Client Client uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  11. WebService WebService WebService Object Viewer Object Display Collaborative Replicated Web Services I • This uses event multicast to support replicated web services Web Service InterceptorProviding General Services Set Collaboration Mode Master Object Object Viewer Object Display Event(Message)Service Object Viewer Object Display uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  12. Collaborative Replicated Web Services II • The event service now replicates the messages INPUT to the master web service (In Collaborative Web Service Access we replicated messages OUTPUT to the client) • Again we use a special “collaboration” port on the Web Service to set up links between clients • Note publish/subscribe mechanism in the events service supports the late joiners (in other collaboration models as well) • The event service can also handle messages between Web services and clients and provide the user customization service but this is not shown on previous foil uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  13. SharedWeb Service SharedDisplay Shared Export Shared Event Object Viewer Object Display Collaboration: Shared Export II • One can use replicated “driver” for shared export DrivingAppl. Object Object’ Master DrivingAppl. Object Viewer Object Display Event(Message)Service DrivingAppl. Object Viewer Object Display uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  14. Object Display Object Display Object Display Object Object Object Object’’ Object’’ Object’’ Collaboration: Shared Event I • Object must be changed in object (application) specific fashion Master Shared Event sharesState change events Event(Message)Service uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  15. Object Display Object Object’’ Collaboration: Shared Event II • Object events can be shared at any point in pipeline Master Shared Event sharesState change events Event(Message)Service Object Display Object’’ Object Display Object’’ uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  16. CollabWS: Collaboration as a Web Service • This includes Audio-Video conferencing, Instant Messengers, shared applications and tools • There are basic standards H323 and SIP • There are peer to peer collaboration approaches like JXTA from Sun • There are various commercial products – Groove Networks effectively defines some shared application interfaces • CollabWS defines a superset of collaboration properties and subservices in XML/WSDL • Then you provide several bindings of collabws.wsdl to new transports and old ones (binary H323) uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  17. H323 SIP JXTA uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  18. SIPH323 JXTA SIP H323 JXTA uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  19. A Typical SIP Message • REGISTER sip:registrar.biloxi.comVia: SIP/2.0/UDP 10.4.1.4:5060To: Bob (sip:bob@biloxi.com)From: Bob (sip:bob@biloxi.com);tag=456248Call-ID:843817637684230@phone21.boxesbybob.comCSeq: 1826 REGISTERContact: (sip:bob@10.4.1.4)Expires: 7200Contact-Length: 0 • Initially build a wrapper that accepts such messages and converts to ….. uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  20. Collaboration as a Web service - now uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  21. SIP as XML • <sipasxml><register> sip:registrar.biloxi.com</register><via> SIP/2.0/UDP 10.4.1.4:5060</via><to> Bob (sip:bob@biloxi.com) </to><from tag="456248" > Bob (sip:bob@biloxi.com) </from><call-id> 843817637684230@phone21.boxesbybob.com</call-id><cseq> 1826 REGISTER </cseq><contact> (sip:bob@10.4.1.4) </contact><expires> 7200 </expires><contact-length> 0 </contact-length></sipasxml> • So this is either an internal format to which we map SIP messages or it is an external format used for Collaboration Web Service uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  22. Future Collaboration Web Service uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  23. Messaging/Events as a Web Service • We can implement messaging subsystem (between WSDL resources) with either direct messages or by a queued system where you publish messages to queues and subscribe as receiver to particular queues • There are many different publish/subscribe models • JMS is a cluster of central servers • JXTA is a very dynamic Peer to Peer model where pipes are queues and topics (metadata) are service advertisements • Implement JMS API with JXTA protocol – different WSDL bindings here have different fault tolerance/reliability semantics • Could use JMS as long distance “carrier” between JXTA peers • JXTA provides higher performance than JMS for nearby recipients uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  24. Destination Source Matching Routing Filter workflow Web Service 1 Web Service 2 (Virtual)Queue WSDLPorts WSDLPorts Event Web Service • Filter is mapping to PDA or slow communication channel (universal access) – see our PDA adaptor • Workflow natural as all messages “intercepted” by Event Web Service • Routing illustrated by JXTA • Destination-Source matching illustrated by JMS uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  25. Resource Data base Broker Network Software multicast P2P: Brokers are clients Broker Broker Broker Broker Broker Broker uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

  26. Narada JXTA/JMS Integration • http://grids.ucs.indiana.edu/ptliupages/projects/narada/ • Is a network of event brokers which can reliably deliver XML specified events • Using openJMS selection module, becomes a distributed or conventional Java Message Service • Linking special JXTAproxies, it can link JXTA communities • Think of JXTA JMS andNarada as differentbindings toevent/messagingweb service uri="http://grids.ucs.indiana.edu/ptliupages/presentations/collabwsncsamar02" email="gcf@indiana.edu"

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