1. Collaborative Web Services and Peer-to-peer Grids
CTS03 Orlando 20 January 2003
PTLIU Laboratory for Community Grids
Geoffrey Fox
Computer Science, Informatics, Physics
Indiana University, Bloomington IN 47404
(Technology Officer, Anabas Corporation, San Francisco)
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2. 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?
Note few applications today have message-based I/O
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
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3. 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
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4. 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 publish/subscribe, 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
For collaboration, this implies one can:
Unify Collaboration Control (H323,SIP ..) as a Web Service
Provide single collaboration messaging environment (Audio/Video, shared display, text chat …)
Develop a generic support for Collaborative Web Services
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5. 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
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6. So what are we doing of interest to CTS?
We co-edited a book on Grid Computing to be published April
We have designed and built a messaging infrastructure NaradaBrokering to support collaboration. Grids and P2P
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 using JMS or Narada for messaging (uses Anabas technology for shared applications)
We have illustrated collaborative pervasive/universal access by subscribing PDA’s and desktop’s to different filtered topics
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
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7. 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
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8. 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 (Open Grid Service Architecture)
Consistent with “rule”: build everything as a Web service
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9. 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
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10. 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, maps, (medical) instruments ….
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
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11. Web Service Architecture for Audio Video Conferencing
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12. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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
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13. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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>
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14. Linking Clients or Servers
Current Implementation Polycom (H323)
Access Grid Admire (Chinese system
Similar to AG) and HearMe SIP VOIP Client Integration
Linking Clients or Servers
Server is Future Project Link Proprietary MCU’s
Illustrated for SIP (HearMe) and Access Grid
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15. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
System Summary
XGSP Specification stable
Will add native XGSP clients
H323 Gateway based on openh323
JMF (Java Media Framework) used for Media Server but will replace JMF by NaradaBrokering for transport
Will describe use of NaradaBrokering for publish/subscribe Media Server
Will add filtering at server to allow codec choice as different topics in JMS/Narada
Initially offer streaming (RealNetworks) or conferencing (H261, MPEG4)
Add P2P (JXTA) interfaces
Add other shared applications using same XGSP control and Narada messaging
Collaboration with Admire Group at Beihang University
Aiming at 1000 students interacting with each other across Internet2 using A/V and Shared Display Summer 2003 (NOT broadcast Webcast)
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16. H323 Client (Polycom) in XGSP Session
XGSP MCU (Control) User Interface
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17. Comparison with other approaches
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18. 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
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19. 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
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20. 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
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21. 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
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22. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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
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23. 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
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24. 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
Transparently replace single server JMS systems with a distributed solution.
Provides reliable inter-peer group messaging for JXTA
Open Source (high quality) messaging
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25. 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 implemented) based on WS-Sec
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26. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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
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27. 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.
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28. Performance/Routing in Message-based Architecture
Satellite UDP
Firewall HTTP
Dial-up Filter A B1
Hand-Held Protocol
Fast Link
Software Multicast B2 B3
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 (individual or collective)
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”
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29. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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
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30. 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
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31. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
All measurements on commodity $1500 Linux PC
Sender/receiver/broker - (Pentium-3, 1 GHz, 256 MB RAM). 100 Mbps LAN. JDK-1.3, Red Hat Linux 7.3
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32. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Sender/receiver/broker - (Pentium-3, 1 GHz, 256 MB RAM). 100 Mbps LAN. JDK-1.3, Red Hat Linux 7.3
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33. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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34. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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35. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Jitter J = J + (|D(i-1, i)| - J)/16
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36. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Narada supports UDP or TCP/IP
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37. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Each Stream 64kbps 60 ms interval
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38. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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39. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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40. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Each Stream average
Bandwidth 600kbps
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41. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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42. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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43. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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44. 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)
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45. Commercial Collaboration Systems
Centra
Anabas
WebEx
Placeware
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46. NaradaBrokering and JMS (Java Message Service)
Low Rate; Small Messages
(commercial JMS)
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47. NaradaBrokering and JXTA
Narada-JXTA provides JXTA guaranteed long distance delivery
Request/Response
Present if targeted at Particular peer
Narada JXTA Event
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48. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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49. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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50. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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51. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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
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52. 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
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53. 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 XPath/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
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54. Federation of Services
If you have a Service – Notification (as with Grid or JXTA advertisements), Search, Scheduling, Audio-Video conferencing ….
With a standard for 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 servers for each island 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
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55. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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”
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56. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
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 with JXTA and MyProfessor Interface
Have implemented shared display, SVG, Text chat, Instant Messenger (using Jabber)
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57. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Collaborative SVG
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58. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
MyProfessor on the PDA
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59. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Sharing Applications
Very few applications are written as Web services
Rather they integrate Rendering and Control
These need to be separated (MVC) 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.
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60. Architecture of Collaborative SVG Application as a Portlet/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
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PDA user
Desktop user

61. 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
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