NaradaBrokeringGrid Messaging and

Applications as Web ServicesGeoffrey Fox

Presenter: Marlon PierceCommunity Grids Lab

Indiana Universitygcf@indiana.edu

NaradaBrokering might Support• Grid Messaging reliably in spirit of WS-

ReliableMessaging• Virtualize inter-service communication• Federate different Grids Together• Scalable pervasive audio-video conferencing• General collaborative Applications and Web services• Build next generation clients interacting with messages

not method-based user interrupts• Unify peer-to-peer networks and Grids• Handle streams as in “media or sensor Grids”• Handle events as in WS-Notification

Minicomputer

Firewall

ComputerServer

PDA

Modem

Laptop computerWorkstationPeers

Peers

Audio/VideoConferencing Client

Audio/VideoConferencing Client

NaradaBrokering BrokerNetwork

NaradaBrokering

Queues

Web Service A

Web Service B

Stream

“GridMPI” v. NaradaBrokering In parallel computing, MPI and PVM provided “all the features

one needed’ for inter-node messaging NB aims to play same role for the Grid but the requirements and

constraints are very different• NB is not MPI ported to a Grid/Globus environment

Typically MPI aiming at microsecond latency but for 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 10-100 frames on client (conferencing to streaming)

• 1 millisecond is time for a Java server to “think” Jitter in latency (transit time through broker) due to routing,

processing (in NB) or packet loss recovery is important property Grids need and can use software supported message functions and

trade-offs between hardware and software routing different from parallel computing

NaradaBrokering Based on a network of cooperating broker nodes

• Cluster based architecture allows system to scale in size Originally designed to provide uniform software

multicast to support real-time collaboration linked to publish-subscribe for asynchronous systems.

Now has several core functions • Reliable order-preserving “Optimized” Message transport

(based on performance measurement) in heterogeneous multi-link fashion with TCP, UDP, SSL, HTTP, and will add GridFTP

• General publish-subscribe including JMS & JXTA and support for RTP-based audio/video conferencing

• Distributed XML event selection using XPATH metaphor• QoS, Security profiles for sent and received messages• Interface with reliable storage for persistent events

Laudable Features of NaradaBrokering

Is open source http://www.naradabrokering.org Has client “plug-in” as well as standalone brokers Will have a discovery service to find nearest brokers Does tunnel through most firewalls without requiring

ports to be opened Supports uniform time across a distributed network Supports JXTA, JMS (Java Message Service) and more

powerful native mode Transit time < 1 millisecond per broker Will have setup and broker network administration

module

NaradaBrokering Naturally Supports Filtering of events to support different client

requirements (e.g,. PDA versus desktop, slow lines, different A/V codecs)

Virtualization of addressing, routing, interfaces Federation and Mediation of multiple instances of Grid

services as illustrated by • Composition of Gridlets into full Grids (Gridlets are single

computers in P2P case)• JXTA with peer-group forming a Gridlet

Monitoring of messages for Service management and general autonomic functions

Fault tolerant data transport Virtual Private Grid with fine-grain Security model

Grid Messaging Substrate

Consumer Service

SOAP+HTTPGridFTPRTP ….

Standard client-serverstyle communication.

Substrate mediatedcommunication removestransport protocol dependence.

Messaging Substrate

Consumer ServiceSOAP+HTTPGridFTPRTP ….

Any Protocol satisfying QoS

e.g. Now can use GridFTP with multi-stream performance boost for any message flow

Virtualizing Communication Communication specified in terms of user goal and Quality of

Service – not in choice of port number and protocol Protocols have become overloaded e.g. MUST use UDP for A/V

latency requirements but CAN’t use UDP as firewall will not support ………

A given communication can involve multiple transport protocols and multiple destinations – the latter possibly determined dynamically

Dial-upFilter

SatelliteUDP

FirewallHTTP

A

B1

Hand-HeldProtocol

FastLink

Software MulticastB2

B3NB Broker Client Filtering

NB Brokers

Performance Monitoring Every broker incorporates a Monitoring service that

monitors links originating from the node. Every link measures and exposes a set of metrics

• Average delays, jitters, loss rates, throughput. Individual links can disable measurements for

individual or the entire set of metrics. Measurement

intervals can also be varied

Monitoring Service, returns measured metrics to Performance Aggregator.

BrokerNode

LinkData

BrokerNode

LinkData

Performance AggregationService

Control MessageExchange

Aggregates infofrom nodes in acertain domain

MonitoringService

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

1-> N Grid Clients

Hypercube ofNB Brokers (logicalnot physical)

N≈100 forDistanceEducationPer edge BrokerScale with distributedBroker net?

NaradaBrokering Communication Applications interface to NaradaBrokering through UserChannels

which NB constructs as a set of links between NB Brokers acting as “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, RTP and HTTP. • GridFTP most interesting new protocol• Supports communication through proxies and firewalls such as

iPlanet, Netscape, Apache, Microsoft ISA and Checkpoint.

Pentium-3, 1GHz, 256 MB RAM100 Mbps LAN

JRE 1.3 Linux

hop-3

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nsit

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isec

onds

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Mean transit delay for message samples in NaradaBrokering: Different communication hops

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Message Payload Size (Bytes)

Standard Deviation for message samples in NaradaBrokering Different communication hops - Internal Machines

hop-2hop-3hop-5hop-7

NaradaBrokering and JMS (Java Message Service)

Low Rate; Small Messages (commercial JMS)

NaradaBrokering and JXTA Federation

Based on hybrid proxy that acts as both Rendezvous peer (JXTA routers) and NaradaBrokering end-point.

No changes to JXTA core or constraints on interactions• Change made to Rendezvous

layer Peers are not aware that

they interact with a Narada-JXTA proxy or Rendezvous peer.

NARADA-JXTA proxy

NARADAbroker cloud

Peers

JXTARendezvousPEER

Dynamic/fluidpeer groups

High end "long lived"/persistent resources

NB provides JXTA guaranteed long distance delivery NB federates multiple JXTA Peer Groups

End-point Services inNative NaradaBrokering

Allows you to create Consumers (subscribers) of events (an event is a time stamped message where time stamp can be empty!)

Allows you to create Producers of events (publishers) Allows you to discover brokers and initialize

communications with the broker. Services available at the client side will perform

• Compression of payloads• Computation of Message digests for Integrity• Secure encryption of payload based on the specified keys• Fragmentation of large payloads into smaller packets• Redundancy service which maintains active (alternate)

connections to multiple brokers.

Event Consumer Capabilities Allow you to subscribe to events that conform to a certain

template.• The specified subscription profile could topic-based strings, XPath

queries, <tag=value> pairs or integer topics.

Event Consumers can also create Consumer constraints to specify various properties regarding the delivery of events.

Consumer constraints are different from subscriptions. • Subscriptions (or Profiles) are evaluated in a distributed fashion by the

broker network,

• Consumer constraints are QoS related and are managed by the QoS services running on the end-point.

Consumer constraints can specify• Reliable Delivery of events

• Ordered (Publisher, causal and time ordered) delivery of events

• Exactly once delivery of events

• Delivery after un-compression of compressed payload

• Delivery after decrypting encrypted payload

Event Producer Capabilities Facilitate the generation of events in correct format

(next slide) Facilitate the publishing of events to brokers Allow the creation of Publisher constraints which

facilitate specification of properties that need to be satisfied by published events

Among the constraints that can be specified include• Method of Securing message payloads

• Computing message digests

• Compressing message payloads

• Fragmenting large payloads

Native NaradaBrokering Event The event comprises of

• Event headers• Content Synopsis (for selection as in JMS properties

WITHOUT reading body)• Content Payload• Dissemination Traces (generated on the fly as event traverses

broker network) This is different from structure of JMS or JXTA events This NBEvent structure supports the extra capabilities discussed

earlier The event headers specify information regarding

• Security and Integrity of encapsulated payload• Fragmentation of events• Compression of payloads• Correlation identifiers (to define ordering between different

streams as is needed in some collaboration applications)• Priority• Application Type• Event Identifiers

Based on Message Level SecurityMessages organized into topicsEach topic has a separate key; Topics can be organized into sessions

Functionality I WebSphere MQ

(formerly MQSeries)Pastry NaradaBrokering

Maximum number of nodes hosting the messaging infrastructure

Medium (MQ is based on the point-to-point model. There is a limit on the effectiveness of this mode in large configurations).

Very large Very large

JMS Compliant Yes No Yes

Guaranteed Messaging (Robust)

Yes Yes Yes

Support for routing P2P Interactions

No Yes JXTA and later Gnutella

Support for Audio/Video Conferencing & raw RTP clients

No No Yes

Communication through proxies and firewalls

Yes No Yes

Support for XPath queries/ subscriptions

No Yes Yes

end-to-end Security Yes No Yes

Network Performance Monitoring

No No Yes

Functionality II WebSphere MQ

(formerly MQSeries)Pastry NaradaBrokering

Workflow Support Yes No NoSupport for P2P distributed caching

No Yes (Squirrel) No

Platforms or Hosting Environments

35 different OS/ platforms supported. Also supports the Java Platform.

Supported on platforms which support C# (Microsoft) or Java (Rice).

Platforms supporting Java 1.4 (tunneling C++)

Maturity of Software

Extremely mature, with very robust diagnostic information

Fair Fair with some “production” testing

Transport Protocols Supported

TCP, HTTP, Multicast, SSL, SNA etc.

TCP, UDP TCP (Blocking and non-blocking), UDP, Multicast, HTTP, SSL, RTP, (GridFTP)

Multiple transport protocols over multiple hops.

Yes No Yes

Broker Network Design Interface

No No In Progress

Autonomic Services In a Web (Grid) Service architecture, the state of any service is defined

by its initial condition and all the messages (including ordering) that it receives• This how shared event model of collaboration works

This is a “Finite State Change” model analogous to saving file and “undo” command in many editors

NB plus a robust store can “guarantee” to save all these messages for (all) services

This allows one to build both "autonomic data transport" and "autonomic services" since these services can sustain packet losses in transport and can also sustain failures of apps/brokers• archived messages (previous invocations, published events etc) can

be retransmitted to reconstruct state at the service or to correct a transport error.

Further anomalies in message traffic (such as a publisher or subscriber are silent) can be detected by NB and signal problems

We are building examples of both scenarios using GridFTP as our data transport example

We will build a sample autonomic visualization service with detection of failed servers and brokers

Reliable Messaging Standards

• There are 2 competing standards in the Web Services community– WS-Reliability from OASIS– WS-ReliableMessaging from IBM and

Microsoft (now expanded to include others)

WS-Reliability & WS-RM • Specifications provide reliable delivery

between two endpoints.• Both the specifications use positive

acknowledgements to ensure reliable delivery

• Both specifications include support for faults

• WS-Reliability is a SOAP based protocol• WS-ReliableMessaging provides an XML

schema for reliable messaging. – Includes a SOAP binding.

NaradaBrokering & Reliable Delivery specifications

• We can provide support for both these specifications – In NaradaBrokering we provide reliable delivery

from multiple points to multiple points

• We have identified issues that will allow federation between these specifications– Sequence numbering, fault mappings,

numbering rollovers, quality of service guarantees

• Federation would allow– WSRM sender & WS-Reliability receiver– WS-Reliability sender & WSRM receiver

WS-ReliabilityWS-RM

SOAP related issues Is a SOAP based protocol, which has an HTTP binding which facilitates acknowledgements and faults to be issued over HTTP responses.

WSRM provides an XML schema for elements needed to support the reliable messaging framework. The specification provides a SOAP binding for the protocol.

Related Specifications SOAP, WS-Security WS-Policy, WS-Security

Unique Ids URI based [RFC 2396], the syntax for the message-ID should be based on what is outlined in RFC2392.

URI based [RFC 2396]. No additional requirement. Messages within a sequence are identified based on message numbers.

Sequence numbering initialization

Starts at 0 for the first message in a group. Starts at 1 for the first message in a group.

Sequence numbering rollover Generate a new group identifier and begin new sequence only after receipt of last message in old sequence.

No new sequences can be generated.MessageRollover fault is issued.

Presence of numbering information and its relation to delivery

REQUIRED only for guaranteed ordering. Message number is REQUIRED for every message that needs to be delivered reliably.

Acknowledgements Can be sent upon receipt of messages, as a callback or in response to a poll. Needed upon receipt of every message.

Acknowledgements can be based on a range of messages, and the timing for issuing this can be advertised in a policy. An endpoint may also choose to send acknowledgements at any time.

Requesting acknowledgements

The AckRequested element is REQUIRED in every message for which reliable delivery needs to be ensured.

AckRequested is used to request the receiving entity to acknowledge the message received. This is not REQUIRED.

Correlation associated with an Acknowledgement

The identifier associated with the message being acknowledged. The identifier associated with the sequence of messages and the message number within that sequence.

Timestamps Are expressed as UTC and conforms to a [XML Schema Part2: Data Types] dateTime element.

No explicit reference to UTC. Uses the dateTime format.

Retransmissions Triggered after receipt of a set of acknowledgements. In the event an acknowledgement is not received, the message is retransmitted until a specified number of resend attempts have been made.

Allows the specification of a RetransmissionInterval for a sequence (effects every message in the sequence). The interval can also be adjusted based on the exponential backoff algorithm.

Quality of Service Is initiated by the sender. WS-Policy assertions are used to meet delivery assurances.

Delivery sequences supported Exactly once ordered delivery, reliable delivery.Order is always tied to guaranteed delivery and cannot be separately specified.

At most once, at least once and exactly once. Order is not necessarily tied to guaranteed delivery.

Security Relies on WS-Security and assorted specifications Relies on WS-Security and assorted specifications

Fault Codes supported by protocol

InvalidMessageHeaderInvalid MessageIdentifierInvalidReferenceToMessageIdInvalidTimeStampInvalidExpiryTimeInvalidReliableMessageInvalidAckRequestedInvalidMessageOrder

SequenceTerminatedUnknown SequenceInvalidAcknowledgementMessageNumberRolloverLastMessageNumberExceeded

NaradaBrokering, WS-Notification & JMS• NaradaBrokering is JMS compliant• Topics in NaradaBrokering could be based on XML,

String(as in JMS), Plain text, Integers, and (tag=value) tuples.– Subscriptions could be XPath queries, SQL queries, Regular

expressions, Strings and integers

• Almost all the primitives needed in WS-Notification are available in NaradaBrokering– Exception: Entities never communicate directly with each

other, as proposed in WS-Notification.– We are either allow such direct communication or mimic in

NB – no performance overhead!

• We are currently building a prototype implementation of WS-Notification

• Need to relate WS-Notification with WS-Eventing and WS-Events

NaradaBrokering and NTP• NaradaBrokering includes an implementation of the

Network Time Protocol (NTP)• All entities within the system use NTP to

communicate with atomic time servers maintained by organizations like NIST and USNO to compute offsets– Offset is the computed difference between global time and

the local time.– The offset is computed based on the time returned from

multiple atomic time servers.• The NTP algorithms weighs results from individual time clocks

based on the distance of the atomic server from the entity.

• NTP ensures that all entities are within 1-30 milliseconds of each other.

• The timestamps account for clock drifts that take place on machines– Time returned is based on software clocks which can slow

down with increased computing load on the machine.

NB Time Service

• In figure on left, there is a NTP daemon running on the local machine besides the NB Time Service. NTP daemon running on the machine adjusts the underlying system clock. NB Time Service shows consistent results with NTP daemon.

• Figure on right shows results on machine that does not run NTP daemon.

offset variations versus elapsed time

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local computer time - msecs

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et c

hang

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offset variations versus elapsed time

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1.073E+12

local computer time - msecsof

fset

cha

nge

- m

secs

• The following results are obtained over a period of 48 hours. • In these tests, NB Time Service computes offset every 30 seconds.

– Usually NTP daemons on Linux/Solaris adjust underlying clock every second.

Building PSE’s with theBuilding PSE’s with theRule of the Millisecond IRule of the Millisecond I

Typical Web Services are used in situations with interaction delays Typical Web Services are used in situations with interaction delays (network transit) of 100’s of milliseconds(network transit) of 100’s of milliseconds

But basic But basic message-based interactionmessage-based interaction architecture only incurs architecture only incurs fraction of a millisecond delayfraction of a millisecond delay

Thus use Web Services to build ALL PSE componentsThus use Web Services to build ALL PSE components• Use messages Use messages and and NOT method/subroutine call or RPCNOT method/subroutine call or RPC

This “rule” OFTEN violated – people use “Java Interfaces” and so This “rule” OFTEN violated – people use “Java Interfaces” and so cannot distribute servicescannot distribute services

Interaction

Nugget1 Nugget2

Nugget3 Nugget4Data

Building PSE’s with theBuilding PSE’s with theRule of the Millisecond IIRule of the Millisecond II

Messaging has several advantages over scripting languagesMessaging has several advantages over scripting languages• Collaboration trivial by sharing messagesCollaboration trivial by sharing messages• Software Engineering due to greater modularitySoftware Engineering due to greater modularity• Web Services do/will have wonderful supportWeb Services do/will have wonderful support

““Loose” Application couplingLoose” Application coupling uses workflow technologies uses workflow technologies Find characteristic interaction timeFind characteristic interaction time (millisecond programs; (millisecond programs;

microseconds MPI and particle) and use microseconds MPI and particle) and use best supported best supported architecture at this levelarchitecture at this level• Two levels: Web Service (Grid) Two levels: Web Service (Grid) and and

C/C++/C#/Fortran/Java/PythonC/C++/C#/Fortran/Java/Python Major difficultyMajor difficulty in frameworks is NOT building them but rather in in frameworks is NOT building them but rather in

supporting themsupporting them• IMHO only hope is to always IMHO only hope is to always minimize life-cycle support risksminimize life-cycle support risks• Science is too small a field to support much!Science is too small a field to support much!

Expect to use DIFFERENT technologies at each level Expect to use DIFFERENT technologies at each level even though even though possible to do everything with one technologypossible to do everything with one technology• Trade off support versus performance/customizationTrade off support versus performance/customization

Streams and Workflow Grids need to consider streams and Services

• Topics in NB are streams not just individual messages There is service-oriented workflow where streams are

typically implicit. For stream-oriented workflow, the streams are explicit.

We have built a sophisticated system GlobalMMCS for audio-video conferencing, which we will discuss next• Media Industry and sensor based science are different

examples We are building a stream control engine for

NaradaBrokering when streams are “just” message flows on the Grid. Here one would use NB discovery services – find streams – and monitor

NB could be used as part of workflow runtime

UNIX-style Workflow Example `flow: x &> (y1|z1 &> p,(q|storage1)), (y2|z2|storage2)`;

Note this approach allows for example all workflow streams to use RMI, GridFTP, RTP – your or rather NaradaBrokering’s choice

x

y1 z1 p

y2 z2 storage2

q storage1

NaradaBrokering Topic (Queue)

Stream–oriented Workflow As in audio-video conferencing and multimedia file

delivery where it’s the media streams that are the “point”

Services generate and transform streams but one thinks of streams going through services rather than services generating streams

Multi-cast streams where video from one client sent to all other participants in a collaborative session common

One thinks of a stream being published and participants subscribing to it.

Pub/Sub QueuePublish

Subscribe

InterGrids Federated Grid using NB Build a P2P Network where each component (cell or Gridlet) is

itself a Grid If cell is a single computer, reduces to using NB to build

communication infrastructure between nodes of P2P network If cell is a JXTA peer group, then InterGrids includes previous

federation of JXTA Peer Groups

Gridlets

NB Brokers

Grid formed fromMultiple cells

InterGrids Mediation Architecture NB acts as a Mediation agent in such a Cellular Grid Using federated security model constructs a VPN like Virtual

Private Grid (NB could support VPN protocol and combine with Grid Security)

Mediation includes more than routing (as in current JXTA) as can map between Interface standards

Each Gridlet can use different Service standards Services register interfaces with mediator giving ways to map

using perhaps OGSA as a common intermediate form Allows integration of OGSI WSRF WS-GAF and “pure web

service” or Jini or JXTA based Grids where each Grid uses its natural service architecture

Support interoperable (like Job Submission) and federated (like registry or metadata catalog) services

Exploits stream filtering capability of NB

Collaboration and Web Services Collaboration has

a) Mechanism to set up members (people, devices) of a “collaborative sessions”

b) Shared generic tools such as text chat, white boards, audio-video conferencing

c) 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 should make it a WS

Shared Event Collaboration All collaboration is about sharing events defining state changes

• Audio/Video conferencing shares events specifying in compressed form audio or video

• Shared display shares events corresponding to change in pixels of a frame buffer

• Instant Messengers share updates to text message streams

• Microsoft events for shared PowerPoint (file replicated between clients) as in Access Grid

Finite State Change NOT Finite State Machine architecture Using Web services allows one to expose updates of all kinds as

messages• “Event service” for collaboration is similar to Grid notification service and we

effectively define SDE’s (service data elements) in OGSI

Group (Session) communication service is needed for the delivery of the update events• Using Event Messaging middleware makes messaging universal

Collaborative SVG Web Service SVG is W3C 2D Vector Graphics standard and is interesting for

visualization and as a simple PowerPoint like application• Further SVG is built on W3C DOM and one can generalize results

to all W3C DOM-based applications (“all” in future?) Apache Batik SVG is Java and open source and so it is practical

to modify it to explore• Real Applications as a Web Service

• Collaboration as a Web Service

• MVC model and web services with implications for portlets We use NaradaBrokering and XGSP to control collaboration;

support PDA Cell-phone and desktop clients; are restructuring Batik as MVC Web Service• Good progress in all areas see

• http://www.svgarena.org for SVG Games

• http://grids.ucs.indiana.edu/ptliupages/projects/carousel/ for PDA

Applications as Web Services? Build “all” classic applications in Web service style with user

interface and “real application” interacting by (WSDL/SOAP) messages and NOT by O/S controlled interrupts• This is “just” MVC (Model View Control) paradigm done very explicitly

• Quite hard because MVC not actually used very systematically

Perhaps the advantages of this architecture could be enough to shake the Microsoft hegemony in both O/S and “productivity” applications• Current challenges of Microsoft applications are trying to do as well and

not easy to see how they can do better

Immediately make a lot easier to support cross O/S applications Form the “Next Generation Client Consortium”?

• There is quite a lot of open source (but not web service based) software with which to begin

Classic MVC ParadigmClassic MVC Paradigm

Model View Controller

Model

Controller

ViewMouse eventKeyboard events

Figure MVC Model

Display

Web Service Model for Application Development

W3C DOM User Interface

W3C DOM Raw (UI) Events

Application as a Web serviceW3C DOM Semantic Events

Data

User FacingPorts

Resource Facing Ports

Events as Messages

Rendering as Messages

View

Control

ModelNarada

Brokering

Interrupts in traditional monolithic applications become“real messages” not directly method callsNatural for collaboration and universal access

Natural inMVC Model

Application as a Web serviceApplication as a Web service

Participating Client

RenderingRendering

User Interface

W3C DOM Events

From Master

FromCollaborationAs a WS

Events

Application as a Web serviceApplication as a Web service

Master Client

RenderingRendering

User Interface

W3C DOM Events

To Collaborative Clients

FromCollaborationAs a WS

Events

Control flow for collaborative SVG clients

Figure 3 Control flow for collaborative SVG clients

Collaborative SVG As A Web ServiceCollaborative SVG As A Web Service

NaradaBrokering

Collaborative SVG Chess Collaborative SVG Chess Game in Batik BrowserGame in Batik Browser

Players

Observers

WSDisplay

WSViewer

WS Display

WS Viewer

Event(Message)

Service

Master

WSDisplay

WS Viewer

Web Service MessageInterceptor

Collaboration as a WSSet up Session with XGSP

Application orContent source

WSDL

Web Service

F

I

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Shared Output Port Collaboration

OtherParticipants

Text ChatWhiteboardMultiplemasters

SVGBrowser

SVGBrowser

SVGBrowser

SVGBrowser

Identical Programs receiving identical eventsToken determines if browser is moving, waiting for opponent or an observer

SIMD Collaboration

SVGViewer

SVGViewer

SVGViewer

SVGViewer

SVG Model (DOM)

NaradaBrokering

Shared Output portSIMD CollaborativeWeb Service

Non Web ServiceImplementation

NaradaBrokering

WSDisplay

WSViewer

WS Display

WS ViewerEvent

(Message)Service

Master

WSDisplay

WS Viewer

Collaboration as a WSSet up Session with XGSP

WebServic

e

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Shared Input Port (Replicated WS) Collaboration

OtherParticipants

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MIMD Collaboration

SVGViewer

SVGViewer

SVGViewer

SVGViewer

NaradaBrokering

Shared Input portMIMD CollaborativeWeb Service

SVG Model

SVG Model

SVG Model

SVG Model

NaradaBrokering

Global-MMCS 2.0 XGSP MCU We are building an open source protocol independent Web

Service “MCU” which will scale to an arbitrary number of users and provide integrated thousands of simultaneous users collaboration services.

We will deploy it globally and hope to test with later this year. The function of A/V media server will be distributed using

NaradaBrokering architecture.• Media Servers mix and convert A/V streams

Open XGSP MCU based on the following open source projects• openh323 is basis of H323 Gateway

• NIST SIP stack is basis of SIP Gateway

• NaradaBrokering is open source messaging from Indiana

• Java Media Framework basis of Media Servers

XGSP Web Service MCU Architecture

SIP H323 Access Grid Native XGSPAdmire

Gateways convert to uniform XGSP Messaging

High Performance (RTP)and XML/SOAP and ..

Media ServersFilters

Session ServerXGSP-based Control

NaradaBrokeringAll Messaging

Use Multiple Media servers to scale to many codecs and manyversions of audio/video mixing

NB Scales asdistributed

WebServices

NaradaBrokering

A/V Collaboration Systems H323

H.323 is defined as an umbrella standard specifying the components to be used within an H.323-based environment.

SIPThe Session Initiation Protocol (SIP) defines how to establish, maintain and terminate Internet sessions including multimedia conferences

Access Grid enhanced Mbone A/V tools ( VIC, RAT )

Internet 2 network ( Multicast support )

XGSP Collaboration Framework To integrate heterogeneous systems into one

collaboration system• A unified, scalable, robust “overlay” network is needed to

support A/V and data group communication over heterogeneous networking environments.

• A common A/V signaling protocol has to be designed to support interactions between different A/V collaboration endpoints.

• Different A/V endpoints should collaborate in the same collaboration session.

Group Communication in Collaboration Collaboration applications usually need a group

communication service for both multipoint data and control information delivery• Centralized conferencing systems usually depend upon a

single conference server • Distributed conferencing systems use IP multicast Access Grid uses Internet2 multicast for audio/video

transmission. • Problems: Centralized conferencing systems don’t have good

scalability and IP multicast has not become ubiquitously available

We use distributed NaradaBrokering to provide this communication

A/V Collaboration over publish/subscribe Middleware video streams (VS) VS {v1, v2, … vm }

audio streams (AS) AS { a1, a2, … an }

A/V endpoints: E1, E2, … El

Each endpoint may send a single or multiple video streams, but only send an audio stream

Different types of A/V endpoints have different collaboration capabilities. • Multicast endpoints are able to receive multiple video and audio

streams, display all the video streams in their screens, and mix all the audio streams by themselves

• Unicast endpoints like Polycom Via Video can only receive and play a single video and audio stream

Publish/subscribe of A/V A stream in VS and AS is regarded as a “topic” Each RTP packet from this stream is regarded as an

“event” for this topic Only the sender of this stream can “publish” A/V events

to this topic Other endpoints need to subscribe to this topic in order

to receive the stream data Create mixed video and audio stream topics for unicast

endpoints

RTP packets encapsulation RTPLink: RTP Packets map to Narada Brokering

Event Every legacy A/V client needs one corresponding

RTPLink to be set up at a broker within broker network.

Unicast RTPLink: Integer Topic Numbers for RTP and RTCP

Multicast RTPLink:

A reflector between NaradaBrokers and multicast groups, encapsulating raw RTP packets from a multicast IP address to RTP events, publishing these events to NaradaBrokers, and forwarding the data it receives from broker network on the same IP address

Audio Mixer, Video Mixer, Image Grabber Audio Mixing

The audio mixer creates a mixed audio stream from all the audio streams in the session

Video Mixing Video mixing makes the unicast users watch the pictures of

multiple participants in a meeting through one video stream Video Thumbnail visualize the VS set in the session, embedded into the control panel

of each endpoint, which Image grabbers capture video streams and save them as static JPEG

files. All the media processing components can be distributed among

the pool of the media servers connected to NaradaBrokering infrastructures.

This generalizes to a farm of “stream servers” doing image processing etc.

H.323, SIP Gateway Servers, A/V Session Server H.323 and SIP gateway transform these protocol

specific messages into XGSP signaling messages so that H.323 and SIP A/V endpoints could communicate with the XGSP A/V session server

The session server implements session management logics • creating/destroying A/V sessions

• allowing endpoints to join/leave session

• Allowing users to make audio/video selection, managing A/V application components

Note Session Server very similar to Context Server in WS-Context

0

10

20

30

40

50

60

0 200 400 600 800 1000 1200 1400 1600 1800 2000

De

lay

(Mill

ise

con

ds)

Packet Number

Average delays per packet for 50 video-clients NaradaBrokering Avg=2.23 ms, JMF Avg=3.08 ms

NaradaBrokering-RTP JMF-RTP

0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Jitte

r (

Mill

ise

con

ds)

Packet Number

Average jitter (std. dev) for 50 video clients.

NaradaBrokering Avg=0.95 ms, JMF Avg=1.10 ms

NaradaBrokering-RTP JMF-RTP

Polycom view of multiple video streams

Polycom, Access Grid and RealVideo views of multiple streams using CGL A/V Web Service

integrating SIP and H323

Unicast AG Portlet

Application Web Servicesand Universal Access

NaradaBrokering can link lightweight clients (V in MVC) to Web Services holding as a Web service the “guts of an application” (M in MVC)• This allows customizable user interfaces gotten by mapping

between client profile protocols at NB

• Supports collaboration between diverse clients

Client1

Client2

M

Agent1

Agent2

ProfilesNB

P1

P2

P

Map P to P1

Map P to P2

Web Service

Integration of PDA, Cell phone and Desktop Grid Access