Collaborative Peer-to-peer Grids for Education and Research

Collaborative Peer-to-peer Grids for Education and Research
Purdue 15 January 2003 PTLIU Laboratory for Community Grids Geoffrey Fox Computer Science, Informatics, Physics Indiana University, Bloomington IN 47404 (Technology Officer, Anabas Corporation, San Francisco) 9/19/2018 uri="

Some Basic Observations/Goals
Technology Support for e-learning is one motivation Need Synchronous and Asynchronous Resource Sharing Can provide universal access using collaboration technology Grids manage and share asynchronous resources in a rather centralized fashion Peer-to-peer networks are “just like” Grids with different implementations of services like registration and look-up Web Services interact with messages Everything (including applications like PowerPoint) will be a WS? Computers are fast and getting faster. One can afford many strategies that used to be unrealistic All messages can be publish/subscribe Software message routing XML will be used for most interesting data and meta-data One will store/consider data and meta-data separately but often use same technology to manage both of them. 9/19/2018 uri="

uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Deductions The system consists of a sea of message-based Services Services inject and extract messages whose transport and manipulation is support by a logically distinct sea of brokers/routers They support adaptive routing, filtering, workflow … They separate logical and actual transport These form a federated XML database and support asynchronous collaboration These process real-time messages in about a millisecond and support synchronous collaboration Basic Unit of information (including events and messages) is a bunch of XML using URI’s to link to other XML or to “other technology capabilities” – Fortran programs, video files, telescopes … This XML includes service meta-data, user profiles, H323 done right, your homework grades, update of framebuffer in shared display etc. 9/19/2018 uri="

So what are we doing I? We co-edited a book on Grid Computing to be published April We have designed and built a messaging infrastructure NaradaBrokering embodying some of these ideas We have shown interoperability between JXTA (Sun’s P2P environment), Java Message Service (JMS) and NaradaBrokering We have deployed a classic (Placeware, Interwise, WebEx) synchronous collaboration environment (Garnet) using JMS or Narada (uses Anabas technology) We have illustrated filtering/universal access by linking PDA’s to desktop collaboration We have prototyped audio-video conferencing as a web service We are repackaging collaborative SVG as a Web service to illustrate (explore) how wonderful it will be when all applications are Collaborative Web services We have started HPSearch Internet Scripting Language project using “search” as access mechanism to web resources 9/19/2018 uri="

So what are we doing II? We have some “Architecture of Computing Portals” including concept of Grid Shell We are building a “Application Web service toolkit” to allow any application to be made a Web service (this only manipulates metadata) Aimed at support of classic Grid applications running on a backend supercomputer This gives Computing Portals for various applications We are building Jetspeed portlets of various types – including collaborative We have thought about integration of XML with more traditional information resources and designed some XML news group technology which uses news group interface to support management and browsing of multiple XML information nuggets (instances) of general Schema Supported by JMS/NaradaBorokering Wizard generates interfaces to define nuggets JSP wizard layout and browsing specification defined by annotating Schema We continue work on HPJava (parallel computing in Java) 9/19/2018 uri="

Classic Grid Architecture
Resources Database Database Content Access Composition Middle Tier Brokers Service Providers Netsolve Security Collaboration Computing Middle Tier becomes Web Services Clients Users and Devices 9/19/2018 uri="

Web Services in a Nutshell
Application or Content source WSDL Web Service Ports: Messages to and from other web services, resources or users Web Services codify a clear process for deploying distributed software components representing Data and Information Sources (Sensors, Databases) Computers Application Software Learning Services like “Submit Homework”, “Grade” System services (OGSA Open Grid Service Architecture) Distributed Message Passing Model We should be in some process of dividing applications (including e-learning) into components and giving them an XML “skin” defining input and output ports (data, remote procedure calls) WSDL Web Service Definition Language 9/19/2018 uri="

Different Web Service Organizations
Everything is a resource (distributed object) implemented as a Web Service, whether it be: back end supercomputers and a petabyte dataset Microsoft PowerPoint and this file Web Services communicate by messages ….. Web Services are “just distributed objects” with focus on (particular) XML specified input and output 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 Roughly but not completely consistent with OGSA Consistent with “rule”: build everything as a Web service 9/19/2018 uri="

Peer to Peer Grid Peers Peers A democratic organization
Database Database Peers Service Facing Web Service Interfaces Event/ Message Brokers Peer to Peer Grid Peers User Facing Web Service Interfaces A democratic organization Peer to Peer Grid 9/19/2018 uri="

Education as a Web Service
“Learning Object” XML standards already exist from IMS/ADL – need to update architecture Web Services for virtual university include: Registration Performance (grading) Authoring of Curriculum Online laboratories for real and virtual instruments Homework submission Quizzes of various types (multiple choice, random parameters) Assessment data access and analysis Synchronous Delivery of Curricula including Audio/Video Conferencing and other synchronous collaborative tools as Web Services Scheduling of courses and mentoring sessions Asynchronous access, data-mining and knowledge discovery Learning Plan agents to guide students and teachers 9/19/2018 uri="

Collaboration and Web Services
Collaboration has Mechanism to set up members (people, devices) of a “collaborative sessions” Shared generic tools such as text chat, white boards, audio-video conferencing Shared applications such as Web Pages, PowerPoint, Visualization b) and c) are “just shared objects” where objects could be Web Services but rarely are at moment We can port objects to Web Services and build a general approach for making Web services collaborative a) is a “Service” which is set up in many different ways (H323 SIP JXTA are standards supported by multiple implementations) – we can make it a WS quite easily 9/19/2018 uri="

Web Service Architecture for Audio Video Conferencing
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XGSP: Introduction Registration Method Session Command Query Session Channel Binding Method Collaboration as a WS Registration Method registration server with its alias name and current location Session Command Method Membership Control Commands, Session Control Commands Query Method discover various properties about the system Session Channel Binding Method (Specific to A/V) bind the RTP channels of a client into the media server 9/19/2018 uri="

XGSP: Example <SessionDes> <SessionName> PervasiveTech Seminar </SessionName> <SessionID> </SessionID> <SessionCreator> </SessionCreator> <SessionInfo> this is a meeting on the XGSP </SessionInfo> <SessionPlace> Lobby Room </SessionPlace> <SessionTime> <StartTime> (EastTime) 10:00AM </StartTime> <EndTime> (EastTime) 12:00AM </EndTime> </SessionTime> <SessionURI> </SessionURI> <SessionParticipants> <Participant> </Participant> <Participant> </Participant> <Participant> </Participant> </SessionParticipants> <ContactInfo> </ContactInfo> </SessionDes> 9/19/2018 uri="

Linking Clients and Servers
Current Implementation Polycom (H323) Access Grid Admire (Chinese system Similar to AG) and HearMe SIP VOIP Integration Future Project Link Proprietary MCU’s Illustrated for SIP (HearMe) and Access Grid Current linkage for Clients not servers 9/19/2018 uri="

Current Status XGSP Specification stable Demo prototype of Polycom (H323), Access Grid, Admire, HearMe clients H323 Gateway based on openh323 JMF (Java Media Framework) used for Media Server XGSP used Internally between audio, video and session control services Codec negotiation supported (No XGSP clients yet) Narada UDP Communication has been successfully tested XGSP MCU (Control) User Interface 9/19/2018 uri="

H323 Client (Polycom) in XGSP Session
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Comparison with other approaches
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Possible A/V Web Service Futures
Productize Narada Integration – needs more testing of Narada multi-protocol interface Will this defeat firewalls that currently spoil my lectures? Integrate video codec shared display system with classic bimap shared display with dynamic choice Session Control Server can be used to define collaborative sessions for other shared applications Text chat etc. Shared SVG, StarOffice, Internet Explorer, Word etc. (using “.net” event interface) Integrate with JXTA interface using Narada-JXTA link Add RealMedia (Windows Media) SIP (VOIP) and native XGSP clients Integrate at server (MCU) level for Polycom, AccessGrid, VOIP – this is Federation 9/19/2018 uri="

Personal View of Collaborative Systems
Originally (at Syracuse) built a collaborative environment Tango and used for online lectures and training sessions from (2001 updated system) Functionality fine but browser interface and network produced instability Hard to build custom collaborative applications Newer simpler (Garnet/Anabas) system addresses these issues although network issues still being addressed Use of XML meta-data and building Education or e-learning as a set of Web Services gives interoperability Use of Grid (as from IBM) and peer-to-peer technology will give improved infrastructure (still quite primitive) 9/19/2018 uri="

Courses at Jackson State
Taught using Tango/Garnet since fall 97 over Internet twice a week from Syracuse/FSU/Indiana Course material same style as online material for in-university classes Curricula, Homework, Grading, Facilities done by “me” Students get JSU NOT Syracuse/Indiana Credit “Trivial” in that learning model identical to that in traditional courses – just changed interaction mode Jackson State major MSI (Minority Serving) University with many computer science graduates Do not compete with base courses but offer addon courses with “leading edge” material (Web Technology, modern scientific computing) which give JSU (under)graduates skills that are important in their career Fall 99 Semester CPS640 offered to 40 students in 5 distant places and separately 40 at Syracuse 9/19/2018 uri="

Lessons from Past “True” Shared Event flexible but too much work for most cases Shared Display – nearly always works Shared Export – SVG PDF HTML X3D etc. can be re-used Integrate synchronous and asynchronous collaboration Do not build into browser as not a reliable or standard virtual machine Build around uniform publish-subscribe style XML Event Model supporting archiving, customization, filtering – apply to all collaboration modes Later we realized need to integrate with Peer to Peer and Web Services (straightforward as XML event model fits these architectures) 9/19/2018 uri="

What is meant to Happen One uses IMS/ADL to define all needed properties in XML Such as Title of page; Address of student etc. Ignore those sensitive to architecture; add some XML specifications such as those to define collaborative sessions One needs “automation”/”support tools” for process of generating meta-data Such as prerequisites for courses; Author of web page etc. One uses conventional authoring tools to build curricula Uses portal technology to integrate user-interfaces to multiple Web Services Unfortunately open approach not used in current Hopefully industry will build needed tools as Web services and interoperability will allow picking and choosing between vendors rather than use of monolithic systems LMS or Learning Management Systems LCMS or Learning Content Management Systems (Use non education specific system) Authoring/Portals (I think it is best NOT to use education specific tools) Collaborative Environments (shared applications) Audio-Video Conferencing 9/19/2018 uri="

Current Status in a Nutshell
Systems such as Centra, WebEx, Garnet and Placeware offer similar functionality to our old system Tango for synchronous collaboration Shared applications, chatroom, whiteboard, A/V conferencing Blackboard, WebCT, Lotus offer learning management systems Not very consistent with modern architectures but can be used effectively today Access Grid (community e.g. classroom) and Polycom (etc.) are excellent audio-video systems I develop research system Garnet for education portals Features hand-held and desktop clients, integrated collaboration and some “technical advances” – major use of XML and publish/subscribe systems Audio-Video Conferencing as a Web Service Improving network robustness including firewall tolerance 9/19/2018 uri="

Commercial Collaboration Systems
Centra Anabas WebEx Placeware 9/19/2018 uri="

Learning Objects Given changing technology, need standards to protect investment in authoring and administrative data generated and stored in databases Education community has unusually good set of community standards Educational Environment Educause set up IMS – Instructional Management System with selection of companies and universities IMS focus was changed to drop implementation work and is now “Global Learning Consortium” Inc. Department of Defense (which has huge training needs) set up ADL Advanced Distributed Learning Initiative whose links section includes all other useful URL’s IEEE (Computing Community) set up P1484 Learning Technology Standards Committee LTSC 9/19/2018 uri="

LMS Model used by ADL Learning Server Content Server(s) External systems: HR, E-Commerce, ERP... Migration Adapter API Application Browser Server Side Client Side HTML+ Services or Adapter Course Interchange: Structure Format (CSF), Metadata Runtime Environment: Launch, API, Data Model “Learning Management System” LMS Critical Interchange Capability Client Server Antiquated Architecture 9/19/2018 uri="

Properties of Learning Objects
Metadata from IEEE and IMS Roughly Properties of educational objects thought of as “documents” (author, title …) Course Packaging, Digital Repositories from SCORM and IMS How to form bigger units of instruction from smaller units Called Content Packaging by IMS and Course Structure Format (CSF) by SCORM which goes in greater depth than IMS Tests and Quizzes from IMS Specialized CSF descriptors from SCORM (via CMI) Such as objectives, prerequisites, completion requirements LMS Runtime API from SCORM – I am doubtful about value Enterprise Properties from IMS Link to people and organization databases (training, human resource, library, student administration) Learner Information Package from IMS Name/Address, Goals, Skills, Grades etc. “Competencies” from IMS “Accessibility” (universal access guidelines) from IMS 9/19/2018 uri="

Learning Management Systems
Most education and training stresses asynchronous or web support for conventional delivery WebCT Blackboard Lotus(IBM) and others offer LMS systems with limited synchronous capability Support typical educational needs like grading, quizzes, homework, glossaries, group Varying database backend and Varying authoring support Popular with colleges as supports not so expert faculty DoD use less clear as need for homework and other tools less critical than for University classes No built in support for areas like “programming labs” (VPL from NPAC did this) 9/19/2018 uri="

Hierarchical Delivery Model
One could teach to 1000 different students – each at a separate workstation but … No real opportunity for questions so better to use broadcast technology – not conferencing Further could better deliver to 40 classrooms – each with an average of 25 students Each classroom has central high quality A/V conferencing, displays and A Mentor monitoring and helping students Each student could have wireless laptop or PDA So synchronous systems must support simultaneously disparate clients – high end display to PC to PDA 9/19/2018 uri="

Authoring of Curriculum
Possible Market pressures push to high end authoring Authoring approaches for the Web can include Basic HTML Macromedia/Adobe/etc. packages like Fireworks, Dreamweaver, Illustrator PowerPoint and Word exported Also can include RealNetworks or Microsoft or .. format Multimedia Note Streaming multimedia formats have larger buffers than A/V conferencing formats Certainly use XML to specify content and render this into attractive portal SVG and SMIL are important 2D vector graphics and multimedia standards HTML does not give reproducible pages Flash can be thought of as “proprietary SVG” 9/19/2018 uri="

Web Services as a Portlet
Each Web Service naturally has a user interface specified as “just another port” Customizable for universal access This gives each Web Service a Portlet view specified (in XML as always) by WSRP (Web services for Remote Portals) So component model for resources “automatically” gives a component model for user interfaces When you build your application, you define portlet at same time Application or Content source WSDL Web Service S R W P Application as a WS General Application Ports Interface with other Web Services User Face of Web Service WSRP Ports define WS as a Portlet WSRP is Web Services for Remote Portals 1st Meeting OASIS March 9/19/2018 uri="

Integration of Portlets
Portals integrate Portlets into a complete user interface Apache Jetspeed seems good open source technology supporting this model Application as a WS General Application Ports Interface with other Web Services Client Render Application or Content source WSDL Web Service Portal User Profile Aggregate UI Fragments S R W P Integrate Multiple Portlets User Customization at either Portal or if complicated at WS User Face of Web Service WSRP Ports define WS as a Portlet 9/19/2018 uri="

Online Knowledge Center built from Portlets
A set of UI Components Web Services provide a component model for the middleware (see large “common component architecture” effort in Dept. of Energy) Should match each WSDL component with a corresponding user interface component Thus one “must use” a component model for the portal with again an XML specification (portalML) of portal component 9/19/2018 uri="

Jetspeed Computing Portal: Choose Portlets
4 available portlets linking to Web Services I choose two 9/19/2018 uri="

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Collaboration: Shared Display
Sharing can be done at any point on “object” or Web Service pipeline Shared Web Service Shared Display Shared Event Shared Export Object Object’ Object’’ Object Display Object Viewer Master Shared Display shares framebuffer with events corresponding to changed pixels in master client. Event (Message) Service Object Display As long as pipeline uses messages, easy to make collaborative Windows framebuffers and in fact most applications do NOT expose a message based update interface Object Display 9/19/2018 uri="

Event (Message) Service
Shared Input Port (Replicated WS) Collaboration Collaboration as a WS Set up Session with XGSP Web Service F I U O R WS Display WS Viewer Master Web Service F I U O R WS Display WS Viewer Event (Message) Service Other Participants Web Service F I U O R WS Display WS Viewer 9/19/2018 uri="

Event (Message) Service
Shared Output Port Collaboration Collaboration as a WS Set up Session with XGSP Web Service Message Interceptor Master Application or Content source WSDL Web Service F I U O R WS Display WS Viewer WS Viewer WS Display Text Chat Whiteboard Multiple masters Event (Message) Service Other Participants WS Viewer WS Display 9/19/2018 uri="

NaradaBrokering Based on a network of cooperating broker nodes Cluster based architecture allows system to scale to arbitrary size Originally designed to provide uniform software multicast to support real-time collaboration linked to publish-subscribe for asynchronous systems. Now has four major core functions Message transport (based on performance measurement) in heterogeneous multi-link fashion General publish-subscribe including JMS & JXTA and support for RTP-based audio/video conferencing Filtering for heterogeneous clients Federation of multiple instances of Grid services 9/19/2018 uri="

Role 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 computing 9/19/2018 uri="

Engineering Issues Addressed by Event / Messaging Service
Application level Quality of Service – e.g. give audio highest priority Tunnel through firewalls & proxies Filter messages to slow (collaborative/real-time) clients Choose Hardware or Software multicast Scaling of software multicast Efficient calculation of destinations and routes. Integrate synchronous and asynchronous collaboration with same messaging, control, archiving for all functions Supports local broker accesses Transparently replace single server JMS systems with a distributed solution. Provides reliable inter-peer group messaging for JXTA 9/19/2018 uri="

NaradaBrokering implements an Event Service
Web Service 1 (Virtual) Queue Web Service 2 Destination Source Matching Filter Routing workflow WSDL Ports Broker Filter is mapping to PDA or slow communication channel (universal access) – see our PDA adaptor Workflow implements message process Routing illustrated by JXTA and includes firewall Destination-Source matching illustrated by JMS using Publish-Subscribe mechanism These use Security model (being designed) based on WS-Sec 9/19/2018 uri="

Features of Event Service
MPI nowadays aims at a microsecond latency The Event Web Service aims at a millisecond (computer) 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 (via other brokers) to subscriber S. Synchronous systems: B acts as a real-time router/filterer Messages can be archived and software multicast Asynchronous systems: B acts as a database & workflow engine Subscription is in each case, roughly equivalent to a database query Company X sets up a firewall The event service sets up brokers either side of firewall to optimize transport through the firewall. 9/19/2018 uri="

Narada Broker Network (P2P) Community For message/events service Broker Broker (P2P) Community Resource Hypercube topology for brokers? Tree for distance education with teacher at root Broker Broker Broker Data base (P2P) Community Software multicast Broker (P2P) Community 9/19/2018 uri="

Performance in Message-based Architecture I
Satellite UDP Firewall HTTP Dial-up Filter A B1 Hand-Held Protocol Fast Link Software Multicast B2 Useful analogies with transportation grids and parallel computing In traveling from cities A to B (say 3 separate passengers), one chooses between and changes transport mechanism at waystations to optimize cost, time, comfort, scenic beauty … Waystations are now NB brokers where one chooses transport protocol Able to choose between car, type of car, plane, train etc Able to dynamically create waystations to cope with problems and acts as hubs for multicast messages Knows about traffic jams and can assign the “HOV lane” B3 9/19/2018 uri="

Performance in Message-based Architecture II
Application level QoS – can optimize among managed streams (audio versus video) using performance subsystem This is just a variant of the NP complete load balancing problem of parallel computing where all reasonable heuristics worked Load-balance in Space-time (strings) not just Space (particles) “Performance” needs to measured carefully as includes QoS I delayed shared application update to ensure audio quality and filtered image to lower resolution So “application” has changed to satisfy performance constraints 9/19/2018 uri="

NaradaBrokering Communication
Applications interface to NaradaBrokering through UserChannels which NB constructs as a set of links between NB Broker waystations which may need to be dynamically instantiated UserChannels have publish/subscribe semantics with XML topics Links implement a single conventional “data” protocol. Interface to add new transport protocols within the Framework Administrative channel negotiates the best available communication protocol for each link Different links can have different underlying transport implementations Implementations in the current release include support for TCP,UDP, Multicast, SSL and RTP. HTTP, HTTPS support will be available in Feb 2003 release. Supports communication through proxies such as iPlanet, Netscape and Apache. Supports communication through firewalls such as Microsoft ISA, Checkpoint. 9/19/2018 uri="

Note on Optimization Note in parallel computing, couldn’t do much dynamic optimization as aiming at microsecond latency Natural to use hardware routing In Grid, time scales are different 100 millisecond quite normal network latency 30 millisecond typical packet time sensitivity (this is one audio or video frame) but even here can buffer frames on client (conferencing to streaming) 1 millisecond is time for a Java server to “think” Jitter in latency (transit time) due to routing, processing (in NB) or packet loss recovery is important property Grid needs and can tolerate significant dynamic optimization 9/19/2018 uri="

Sender/receiver/broker - (Pentium-3, 1 GHz, 256 MB RAM). 100 Mbps LAN. JDK-1.3, Red Hat Linux 7.3 9/19/2018 uri="

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H.263 video file Average bit-rate of 600Kbps. Frame-rate of 30 frames/sec Jitter J = J + (|D(i-1, i)| - J)/16 Jitter J is defined by the RTP RFC as the mean deviation (smoothed absolute value) of the difference D in packet spacing at the receiver compared to the sender for a pair of packets Jitter represents the jitter value up until that point in the sample. 9/19/2018 uri="

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Narada/JMS and Collaboration
Collaboration involves sharing resources and synchronous collaboration involves coordinating a common view of a resource between multiple clients Typically one client is “in charge” and others get initial and updated resource from this “master” Specification of initial state of resource and its change are “just XML events” and we (Anabas and Indiana) have used first JMS and now NaradaBrokering to implement the transport of update events between collaborating clients Update events include: text you type into text chat or Instant Messenger URL defining shared browser Change in framebuffer for (most flexible) shared display Microsoft events for shared PowerPoint (file replicated between clients) 9/19/2018 uri="

NaradaBrokering and JMS (Java Message Service)
Low Rate; Small Messages (commercial JMS) 9/19/2018 uri="

NaradaBrokering and JXTA
Narada-JXTA provides JXTA guaranteed long distance delivery Request/Response Present if targeted at Particular peer Narada JXTA Event 9/19/2018 uri="

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Narada Performance Web Service
Performance measurements are used by Links in Reconfiguring Connectivity between nodes Deciding underlying transport protocol Determining possible filtering Each node determines performance of links of which it is endpoint Individual node web services are aggregated as another Web Service Probably should replace by a more sophisticated measurement package Factors measured include Transit delays, bandwidth, Jitter, Receiving rates. Performance measurements are Spaced out at increasing intervals for healthy channels. Factors selectively measured for unhealthy channels. No repeated measurements of bandwidth for example. Injected into Narada network as XML events Administrative Interface 9/19/2018 uri="

Narada Link Firewall Architecture
Control Channel (TCP) Specifics tunnel destination, parameters. [ SOAP port 80 ] Config Specifics default tunnel destination, parameters. Non-Firewall Proxy CTL SSL Tunnel Server Proxy UDP TCP SSL Tunnel Client Proxy SSL Lib API TCP UDP Firewall Proxy Fake SSL Impl. JSSE Impl. WinINET Impl. Proxy Detection API Required for MS Authentication support. Text Config WinINET Detection Required for Proxy location detection Narada Link Firewall Architecture 9/19/2018 uri="

Start UDP Works Stream Media Types Connection Complete Doesn’t Work Start TCP Works Reliable Data Stream Doesn’t Work Windows ? WinINET Try SSL first then HTTP Works NaradaBrokering Link Transport Firewall Heuristic Doesn’t Work Try SSL Over HTTPS Proxy Does HTTPS Proxy Exist Works Yes Doesn’t Work Try HTTP Over HTTP Proxy Does HTTP Proxy Exist Works Yes Doesn’t Work “Fake” SSL Over Direct Try SSL Over Direct Try HTTP Direct Works Doesn’t Work Doesn’t Work Works 9/19/2018 uri="

Architecture of Message Layer
Need to optimize not only routing of particular messages but classic publish/subscribe problem of integrating different requests with related topics (subscribe to sports/basketball/lakers and sports) Related to Akamai, AOL … caching and Server optimization problem Hypercube of NB Brokers (logical not physical) N≈100 for Distance Education Scale to billions of grid nodes? 1-> N Grid Nodes 9/19/2018 uri="

NaradaBrokering as an XML database
NB is inevitably a distributed XML database supporting real-time update and access (JMS uses SQL like syntax) Performance data Event Logging Published “properties” of publish/subscribe messages Publish as XML topic; subscribe using XQuery? We use NB as a simple XML database for News groups and other “XML nuggets” see XML Instance==Message; what is difference between a message and a database record except performance but Moore’s law is rewriting rules here Subscribe a real database (Oracle) to all topics for reliable storage 9/19/2018 uri="

Federation of Services
If you have a service – Notification (as with Grid or JXTA advertisements), Search, Scheduling, Audio-Video conferencing …. With a standard which client and server components Then can build a “server” that services all clients Alternatively can hierarchically consider collection of existing Server-client domains IBM or Globus OGSA islands Sun Grid Engine Schedulers Polycom/Access Grid A/V sessions Enterprise Search Engines Federation links islands together JXTA Search has XML specified federation approach – will try to include and generalize as a NaradaBrokering federation framework DoD High Level Architecture HLA does this for simulation NB Hub 9/19/2018 uri="

Filtering Service As (real-time) collaboration uses publish-subscribe, we can and in fact must map/filter “object renderings” or updates to them differently for each class of client In distance education, needed for example to Cope with mix of Internet2 and dial-up clients (the student who overslept and is at home) Allow PDA’s (Personal Digital Assistants) and desktops to be in same session To allow Blind users to select the purely audio version of some content Mapping in event service enables universal access Note clients’ subscription to publish/subscribe service includes “user profile” 9/19/2018 uri="

Collaborative PDA Extendable to more general universal access Can implement filter either as an insertion in message stream or in batch mode where a Service subscribes to event stream (one collaborative application or “sharedlet”), filters it and reposts to a different stream We developed first case with a special adaptor that is essentially a NaradaBrokering node that Has added filters controlled by client profile Has stripped down special purpose link protocol HHMS (Hand held message service) optimized for PDA Currently implemented as MyProfessor for Windows CE iPAQ Working on Palm OS Cell-PDA combination Have implemented shared display, SVG, Text chat, Instant Messenger (using Jabber) 9/19/2018 uri="

PDA Collaboration Event Filter
Pass Through Shared Display GMS = JMS or Narada Lightweight Narada Hand Held Link Protocol 9/19/2018 uri="

Collaborative SVG 9/19/2018 uri="

MyProfessor on the PDA 9/19/2018 uri="

Sharing Applications Very few applications are written as Web services Rather they integrate Rendering and Control These need to be separated for Easy Collaborative model Use on devices with limited rendering or for users requesting custom rendering Note important standards like W3C DOM do not separate Trap User Events Inject User Events “NaradaBrokering” Pre Web Service Shared Event Collaboration Rendering non-Master IE Word etc. Master IE Word etc. 9/19/2018 uri="

Architecture of Collaborative SVG Application as a WebService
content server SVG Document Rendering Engine {JMS, NB} Client Controlling Event Session manager New/Updated Content SVG portlet Portlet A Portlet B Event Service {NaradaBrokering…} Chosen Rendering & Update Jetspeed Portlet Control Portlet Controller Turbine Screen Controlling Event New/Updated Content Setup HTTP request HTML content HTTP request HTML/WML content Controlling Event Communication Adaptor for PDAs New/Updated Content HHMS HTTP Client HTTP Client HHMS {JMS, NB} Client HHMS Client Minimum collaborative environment Minimum collaborative environment 9/19/2018 uri=" PDA user Desktop user

Select Collaborative SVG Portlet : HTML
for Desktop environment 9/19/2018 uri="

Collaborative content viewer for Users
Input URL of SVG document Browse Ready-to-use image from SVG content WS Catch user’s collaborative events from viewer 9/19/2018 uri="

Customized User-Facing Ports
User Profile Application or Content source WSDL Web Service F I U O R Render Portal (Aggregator) Selector Filter Control Channel Customized View Selection View (NaradaBrokering) Event Service Customized User-Facing Ports As used in Universal Access 9/19/2018 uri="

Different Models for Rendering
Current Collaborative SVG leaves Batik SVG browser largely unchanged but wrapped as a Web Service User sees a simple (say JPEG) rendering Very convenient for annotations etc. Alternatively take Batik source and split into two Control (Model and Control in MVC) and Render/Catch User actions (View in MVC) Build messaging interface between Model/Control and View and only wrap Model/Control section Model Control Native Render (view) Native Render (view) Model Control Image View Web Service Web Service Convert View 9/19/2018 uri="

Invertible User View Transformations
Minimal Client Control Transform Transform DAT CTL CTL CTL DTX DTX DTX ….. ….. ….. DTX DTX DTX FPCL FPCL PPCL MCL DTX User Portlet Defining data And model Each of these is some sort of DOM Content Web Service DAT defines data/model of a Content Web Service CTL defines control of a Content Web Service DTX is a typical transformation e.g. XSLT action MCL is client interface – simplest is just an image with mouse click positions recognized Universal Access or Collaboration requires that Control (CTL) be properly supported by MCL – this requires that all transformations must be “invertible” whether DOM “semantic” (Interpretable directly by CTL) or not (position of mouse click etc.) 9/19/2018 uri="

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