Transcript Architecture of Web Service Grids IIT Computer Science Colloquium October 25 2004 Geoffrey Fox Community Grids Lab Indiana University [email protected].

Architecture of
Web Service Grids
IIT Computer Science
Colloquium
October 25 2004
Geoffrey Fox
Community Grids Lab
Indiana University
[email protected]
e-Infrastructure



e-Infrastructure builds on the inevitable increasing performance
of networks and computers linking them together to support new
flexible linkages between computers, data systems and people
• Grids and peer-to-peer networks are the technologies that
build e-Infrastructure
• e-Infrastructure called CyberInfrastructure in USA
We imagine a sea of conventional local or global connections
supported by the “ordinary Internet”
• Phones, web page accesses, plane trips, hallway conversations
• Conventional Internet technology manages billions of
broadcast or low (one client to Server) or broadcast links
On this we superimpose high value multi-way organizations
(linkages) supported by Grids with optimized resources and
system support and supporting virtual (electronic) enterprises
• Low multiplicity fully interactive real-time sessions
• Resources such as databases supporting (larger) communities
Philosophy of Web Service Grids
• Much of Distributed Computing was built by natural
extensions of computing models developed for sequential
machines
• This leads to the distributed object (DO) model represented
by Java and CORBA
– RPC (Remote Procedure Call) or RMI (Remote Method
Invocation) for Java
• Key people think this is not a good idea as it scales badly
and ties distributed entities together too tightly
– Distributed Objects Replaced by Services
• Note CORBA was considered too complicated in both
organization and proposed infrastructure
– and Java was considered as “tightly coupled to Sun”
– So there were other reasons to discard
• Thus replace distributed objects by services connected by
“one-way” messages and not by request-response messages
Humans
Programs
Computational resources
service logic
BPEL, Java, .NET
Databases
SOAP and WSDL
• Web Services build
loosely-coupled,
distributed applications,
(wrapping existing codes
and databases) based on
the SOA (service oriented
architecture) principles.
• Web Services interact by
exchanging messages in
SOAP format
• The contracts for the
message exchanges that
implement those
interactions are described
via WSDL interfaces.
<env:Envelope>
<env:Header>
...
</env:header>
<env:Body>
...
</env:Body>
</env:Envelope>
SOAP messages
message processing
Web services
resources
Devices
What is a Grid?
• You won’t find a clear description of what is Grid and how
does differ from a collection of Web Services
– I see no essential reason that Grid Services have different
requirements than Web Services
– Geoffrey Fox, David Walker, e-Science Gap Analysis, June 30
2003. Report UKeS-2003-01,
http://www.nesc.ac.uk/technical_papers/UKeS-2003-01/index.html.
– Notice “service-building model” is like programming language –
very personal!
• Grids were once defined as “Internet Scale Distributed
Computing” but this isn’t good as Grids depend as much if
not more on data as well as simulations
• So Grids can be termed “Internet Scale Distributed
Services” and represent a way of collecting services
together to solve problems where special features and
quality of service needed.
Community Resources


Grid Community databases have analogy to Television and the
News Web that allow individuals to communicate instantly with
each other via Web Pages and Headline News acting as proxies
N resources deposit information and N can view – Complexity
O(N)
Large and Small Grids




N resources in a community (N is billions for the world
and 1000-10000 for many scientific fields)
Communities are arranged hierarchically with real work
being done in “groups” of M resources – M could be 10100 in e-Science
Metcalfe’s law: value of network grows like square of
number of nodes M – we call Grids where this true
Metcalfe or M2 Grids
Nature of Interaction depends on size of M or N
• Shared Information O(N) Complexity Grids for largish N
• Complexity M2 Metcalfe Grids for smaller M < N

Grids must merge with peer-to-peer networks to support
both Complexity O(N) and M2 Systems
M2 Interactions
• Superimpose M2
“Grids” on the sea
(heatbath) of O(N)
“ordinary”
interactions
Architecture of (Web Service) Grids



Grids built from Web Services communicating through
an overlay network built in SOFTWARE on the
“ordinary internet” at the application level
Grids provide the special quality of service (security,
performance, fault-tolerance) and customized services
needed for “distributed complex enterprises”
We need to work with Web Service community as they
debate the 60 or so proposed Web Service specifications
•
•
•
•
Use Web Service Interoperability WS-I as “best practice”
Must add further specifications to support high performance
Database “Grid Services” for O(N) Community case
Streaming support for M2 case
Web Services WS-*
• Java is very powerful partly due to its many “frameworks” that
generalize libraries e.g.
– Java Media Framework
– Java Database Connectivity JDBC
• Web Services have a correspondingly collections of specifications
that represent critical features of the distributed operating systems
for “Grids of Simple Services”
– Some 60 active WS-* specifications for areas such as
– a.
Core Infrastructure Specifications
– b.
Service Discovery
– c.
Security
– d.
Messaging
– e.
Notification
– f.
Workflow and Coordination
– g.
Characteristics
– h.
Metadata and State
– i.
User Interfaces
A List of Web Services I
• a) Core Service Architecture
• XSD XML Schema (W3C Recommendation) V1.0 February 1998,
V1.1 February 2004
• WSDL 1.1 Web Services Description Language Version 1.1, (W3C
note) March 2001
• WSDL 2.0 Web Services Description Language Version 2.0, (W3C
under development) March 2004
• SOAP 1.1 (W3C Note) V1.1 Note May 2000
• SOAP 1.2 (W3C Recommendation) June 24 2003
• b) Service Discovery
• UDDI (Broadly Supported OASIS Standard) V3 August 2003
• WS-Discovery Web services Dynamic Discovery (Microsoft,
BEA, Intel …) February 2004
• WS-IL Web Services Inspection Language, (IBM, Microsoft)
November 2001
A List of Web Services II
• c) Security
• SAML Security Assertion Markup Language (OASIS) V1.1 May
2004
• XACML eXtensible Access Control Markup Language (OASIS)
V1.0 February 2003
• WS-Security 2004 Web Services Security: SOAP Message
Security (OASIS) Standard March 2004
• WS-SecurityPolicy Web Services Security Policy (IBM,
Microsoft, RSA, Verisign) Draft December 2002
• WS-Trust Web Services Trust Language (BEA, IBM, Microsoft,
RSA, Verisign …) May 2004
• WS-SecureConversation Web Services Secure Conversation
Language (BEA, IBM, Microsoft, RSA, Verisign …) May 2004
• WS-Federation Web Services Federation Language (BEA, IBM,
Microsoft, RSA, Verisign) July 2003
A List of Web Services III
• d) Messaging
• WS-Addressing Web Services Addressing (BEA, IBM, Microsoft)
March 2004
• WS-MessageDelivery Web Services Message Delivery (W3C
Submission by Oracle, Sun ..) April 2004
• WS-Routing and Referral SOAP Routing Protocol (Microsoft) October 2001
• WS-RM Web Services Reliable Messaging (BEA, IBM, Microsoft,
Tibco) v0.992 March 2004
• WS-Reliability Web Services Reliable Messaging (OASIS Web Services
Reliable Messaging TC) March 2004
• SOAP MOTM SOAP Message Transmission Optimization Mechanism
(W3C) June 2004
• e) Notification
• WS-Eventing Web Services Eventing (BEA, Microsoft, TIBCO) January
2004
• WS-Notification Framework for Web Services Notification with WSTopics, WS-BaseNotification, and WS-BrokeredNotification (OASIS)
OASIS Web Services Notification TC Set up March 2004
• JMS Java Message Service V1.1 March 2002
A List of Web Services IV
• f) Coordination and Workflow, Transactions and Contextualization
• WS-CAF Web Services Composite Application Framework including WS-CTX,
WS-CF and WS-TXM below (OASIS Web Services Composite Application
Framework TC) July 2003
• WS-CTX Web Services Context (OASIS Web Services Composite Application
Framework TC) V1.0 July 2003
• WS-CF Web Services Coordination Framework (OASIS Web Services Composite
Application Framework TC) V1.0 July 2003
• WS-TXM Web Services Transaction Management (OASIS Web Services
Composite Application Framework TC) V1.0 July 2003
• WS-Coordination Web Services Coordination (BEA, IBM, Microsoft) September
2003
• WS-AtomicTransaction Web Services Atomic Transaction (BEA, IBM, Microsoft)
September 2003
• WS-BusinessActivity Web Services Business Activity Framework (BEA, IBM,
Microsoft) January 2004
• BTP Business Transaction Protocol (OASIS) May 2002 with V1.0.9.1 May 2004
• BPEL Business Process Execution Language for Web Services (OASIS) V1.1 May
2003
• WS-Choreography (W3C) V1.0 Working Draft April 2004
• WSCI (W3C) Web Service Choreography Interface V1.0 (W3C Note from BEA,
Intalio, SAP, Sun, Yahoo)
• WSCL Web Services Conversation Language (W3C Note) HP March 2002
A List of Web Services V
• h) Metadata and State
• RDF Resource Description Framework (W3C) Set of recommendations expanded
from original February 1999 standard
• DAML+OIL combining DAML (Darpa Agent Markup Language) and OIL
(Ontology Inference Layer) (W3C) Note December 2001
• OWL Web Ontology Language (W3C) Recommendation February 2004
• WS-DistributedManagement Web Services Distributed Management Framework
with MUWS and MOWS below (OASIS)
• WSDM-MUWS Web Services Distributed Management: Management Using Web
Services (OASIS) V0.5 Committee Draft April 2004
• WSDM-MOWS Web Services Distributed Management: Management of Web
Services (OASIS) V0.5 Committee Draft April 2004
• WS-MetadataExchange Web Services Metadata Exchange (BEA,IBM,
Microsoft, SAP) March 2004
• WS-RF Web Services Resource Framework including WS-ResourceProperties,
WS-ResourceLifetime, WS-RenewableReferences, WS-ServiceGroup, and
WS-BaseFaults (OASIS) Oasis TC set up April 2004 and V1.1 Framework March
2004
• ASAP Asynchronous Service Access Protocol (OASIS) with V1.0 working draft G
June 2004
• WS-GAF Web Service Grid Application Framework (Arjuna, Newcastle
University) August 2003
A List of Web Services VI
• g) General Service Characteristics
• WS-Policy Web Services Policy Framework (BEA, IBM,
Microsoft, SAP) May 2003
• WS-PolicyAssertions Web Services Policy Assertions
Language (BEA, IBM, Microsoft, SAP) May 2003
• WS-Agreement Web Services Agreement Specification
(GGF under development) May 2004
• i) User Interfaces
• WSRP Web Services for Remote Portlets (OASIS)
OASIS Standard August 2003
• JSR168: JSR-000168 Portlet Specification for Java
binding (Java Community Process) October 2003
A List of Web Services VII
• j) Recent Updates …………………
• WS-Eventing important update of this notification specification
with IBM, Sun and others joining Microsoft et al. as authors
• WS-Enumeration supporting the splitting of a single entity (file
or stream) into multiple messages
• WS-Transfer supporting the creation, update (by get or put) or
deletion of a resource
• WS-Management competes with WS-DM to provide a Web
Service to manage resources
• WS-PolicyAttachment describes how to associate policies with
UDDI and Endpoints and how to integrate with WSDL
• WS-DAI is a Web Service of the OGSA-DAI Grid linkage with
databases
• WS-CIM is a Web Service rendering from DMTF (Distributed
Management Task Force) of the industry standard CIM
(Common Information Model) of metadata for computer devices
• The WS-* implicitly define an architecture
Importance of SOAP
• SOAP defines a very obvious message structure with a
header and a body
• The header contains information used by the “Internet
operating system”
– Destination, Source, Routing, Context, Sequence
Number …
• The message body is partly further information used by the
operating system and partly information for application
when it is not looked at by “operating system” except to
encrypt, compress it etc.
– Note WS-Security supports separate encryption for
different parts of a document
• Much discussion in field revolves around what is referenced
in header!
– e.g. WSRF adds a lot to header
Deployment Issues for “System Services”
• “System Services” are ones that act before the real
application logic of a service
• They gobble up part of the SOAP header identified
by the namespace they care about and possibly part
or all of the SOAP body
– e.g. the XML elements in header from the WS-RM
namespace
• They return a modified SOAP header and body to
next handler in chain
Header
Body
WS-RM
Handler
WS-……..
Handler
e.g. ……. Could be WS-Eventing WS-Transfer ….
Messaging Structure
•
Communication Services are messaging
(transport protocol, routing) using SOAP
protocol
Service
itself
Messaging
Process SOAP
Body
Header
Service
itself
Process SOAP
Header Body
Customizable Handler
Chain processes
SOAP Header
Invoke Other Services
from Header or Body
Proxy Distributed Processing
• A handler is like an in memory “service” so one can build
handlers that can alternatively be deployed “outside”
application service and look like a service.
– Natural for some cases like Reliable Messaging but
always possible
• Support and architecture of handlers/services
that can be inside or outside containers is not clear?
– Build virtual (distributed) containers
Legacy
Service
WS-RM
Service
WS-RM enabled
SOAP
WS-RM removed
from SOAP Header
WS-I Interoperability
• Critical underpinning of Grids and Web Services is the
gradually growing set of specifications in the Web Service
Interoperability Profiles
• Web Services Interoperability (WS-I) Interoperability
Profile 1.0a." http://www.ws-i.org. gives us XSD,
WSDL1.1, SOAP1.1, UDDI in basic profile and parts of
WS-Security in their first security profile.
• We imagine the “60 Specifications” being checked out and
evolved in the cauldron of the real world and occasionally
best practice identifies a new specification to be added to
WS-I which gradually increases in scope
– Note only 4.5 out of 60 specifications have “made it” in this
definition
Web Services Grids and WS-I+
• WS-I Interoperability doesn’t cover all the capabilities need to
support Grids
• WS-I+ is designed to minimal extension of WS-I to support
“most current” Grids: it adds support for
– Enhanced SOAP Addressing (WS-Addressing)
– Fault tolerant (reliable) messaging
– Workflow as in IBM-Microsoft standard BPEL
• Security and Notification best practice and support will probably
get added soon
– There are Web Service frameworks here but various IBM v Microsoft v
Globus differences to be resolved
• Portlet-based User Interfaces could be added
• UK OMII Open Middleware Infrastructure Institute is adopting
this approach to support UK e-Science program
– Currently UK e-Science largely either uses GT2 (as in EDG) or Simple
Web Services for “database Grids”
– http://www.omii.ac.uk/
Application Specific Grids
Generally Useful Services and Grids
Workflow WSFL/BPEL
Service Management (“Context etc.”)
Service Discovery (UDDI) / Information
Service Internet Transport  Protocol
Service Interfaces WSDL
Base Hosting Environment
Protocol HTTP FTP DNS …
Presentation XDR …
Session SSH …
Transport TCP UDP …
Network IP …
Data Link / Physical
Higher
Level
Services
Service
Context
Service
Internet
Bit level
Internet
(OSI
Stack)
Layered Architecture for Web Services and Grids
Working up from the Bottom





We have the classic (CISCO, Juniper ….) Internet routing the
flood of ordinary packets in OSI stack architecture
Web Services build the “Service Internet” or IOI (Internet on
Internet) with
• Routing via WS-Addressing not IP header
• Fault Tolerance (WS-RM not TCP)
• Security (WS-Security/SecureConversation not IPSec/SSL)
• Data Transmission by WS-Transfer not HTTP
• Information Services (UDDI/WS-Context not
DNS/Configuration files)
• At message/web service level and not packet/IP address level
Software-based Service Internet possible as computers “fast”
Familiar from Peer-to-peer networks and built as a software
overlay network defining Grid (analogy is VPN)
SOAP Header contains all information needed for the “Service
Internet” (Grid Operating System) with SOAP Body containing
information for Grid application service
Consequences of Rule of the Millisecond
• Useful to remember critical time scales
– 1) 0.000001 ms
– CPU does a calculation
– 2a) 0.001 to 0.01 ms – Parallel Computing MPI latency
– 2b) 0.001 to 0.01 ms – Overhead of a Method Call
– 3) 1 ms
– wake-up a thread or process
– 4) 10 to 1000 ms – Internet delay
• 2a), 4) implies geographically distributed metacomputing
can’t in general compete with parallel systems
• 3) << 4) implies a software overlay network is possible
without significant overhead
– We need to explain why it adds value of course!
• 2b) versus 3) and 4) describes regions where method and
message based programming paradigms important
Linking Modules
Closely coupled Java/Python …
Module
B
Module
A
Method Calls
.001 to 1 millisecond

Coarse Grain Service Model
Service
B
Messages
Service
A
0.1 to 1000 millisecond latency
From method based to RPC to message based to event-based
publish-subscribe Message Oriented Middleware
“Listener”
Subscribe
to Events
Service B
Publisher
Post Events
Message Queue in the Sky
Service A
What is a Simple Service?
• Take any system – it has multiple functionalities
– We can implement each functionality as an independent distributed
service
– Or we can bundle multiple functionalities in a single service
• Whether functionality is an independent service or one of many
method calls into a “glob of software”, we can always make them as
Web services by converting interface to WSDL
• Simple services are gotten by taking functionalities and making as
small as possible subject to “rule of millisecond”
– Distributed services incur messaging overhead of one (local) to
100’s (far apart) of milliseconds to use message rather than method
call
– Use scripting or compiled integration of functionalities ONLY
when require <1 millisecond interaction latency
• Apache web site has many projects that are multiple functionalities
presented as (Java) globs and NOT (Java) Simple Services
– Makes it hard to integrate sharing common security, user profile,
file access .. services
•
•
•
•
•
Grids of Grids of Simple Services
Link via methods  messages  streams
Services and Grids are linked by messages
Internally to service, functionalities are linked by methods
A simple service is the smallest Grid
We are familiar with method-linked hierarchy
Lines of Code  Methods  Objects  Programs  Packages
Methods
CPUs
Services
Clusters
Component Grids
Compute
Resource Grids
MPPs
Databases
Sensor
Federated
Databases
Sensor Nets
Data
Resource Grids
Overlay
and Compose
Grids of Grids
Component Grids?
• So we build collections of Web Services which we
package as component Grids
–
–
–
–
–
–
–
Visualization Grid
Sensor Grid
Utility Computing Grid
Person (Community) Grid
Earthquake Simulation Grid
Control Room Grid
Crisis Management Grid
• We build bigger Grids by composing component
Grids using the Service Internet
Flood CIGrid
…
Electricity
CIGrid
…
Gas Services
and Filters
Flood Services
and Filters
Collaboration Grid
Sensor Grid
Registry
Gas CIGrid
Portals
GIS Grid
Data Access/Storage
Visualization Grid
Compute Grid
Metadata
Core Grid Services
Security
Notification
Workflow
Messaging
Physical Network
Critical Infrastructure (CI) Grids built as Grids of Grids
Repositories
Federated Databases
Database
Sensors
Streaming
Data
Field Trip Data
Database
Sensor Grid
Database Grid
Research
SERVOGrid
Education
Compute Grid
Data
Filter
Services Research
Simulations
?
GIS
Discovery Grid
Services
Analysis and
Visualization
Portal
Geoscience Research and Education Grids
Customization
Services
From
Research
to Education
Education
Grid
Computer
Farm
IOI and CIE
• Let us study the two layers IOI (Service Internet On the Bit Internet)
and CIE (Service Context and Information Environment)
• IOI is most “straightforward” as it is providing reasonably well
understood capabilities at a new “level”
• CIE is roughly the inter-service “shared memory” used to manage and
control them at “distributed operating system level
– Critical is “shared” (a database service) versus message based CIE
Application Specific Grids
Generally Useful Services and Grids
Workflow WSFL/BPEL
Service Management (“Context etc.”)
Service Discovery (UDDI) / Information
Service Internet Transport  Protocol
Service Interfaces WSDL
Higher
Level
Services
CIE
IOI
NaradaBrokering
Audio/Video
Conferencing Client
Computer
Modem
Minicomputer
Server
Web Service B
Peers
NaradaBrokering Broker
Network
Firewall
Queues
Stream
Server-enhanced
Messaging
Workstation
Laptop computer
Peers
PDA
Audio/Video
Conferencing Client
NB supports messages
and streams
“GridMPI” v. “Service Internet”


In parallel computing, MPI and PVM provided “all the features
one needed’ for inter-node messaging
Service Internet implemented by 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
Current NaradaBrokering Features
Multiple protocol
transport support
In publish-subscribe
Paradigm with different
Protocols on each link
Transport protocols supported include TCP, Parallel TCP
streams, UDP, Multicast, SSL, HTTP and HTTPS.
Communications through authenticating proxies/firewalls &
NATs. Network QoS based Routing
Allows Highest performance transport
Subscription Formats
Subscription can be Strings, Integers, XPath queries, Regular
Expressions, SQL and tag=value pairs.
Reliable delivery
Robust and exactly-once delivery in presence of failures
Ordered delivery
Producer Order and Total Order over a message type. Time
Ordered delivery using Grid-wide NTP based absolute time
Recovery and Replay
Recovery from failures and disconnects.
Replay of events/messages at any time. Buffering services.
Security
Message-level WS-Security compatible security
Message Payload options
Compression and Decompression of payloads
Fragmentation and Coalescing of payloads
Messaging Related
Compliance
Java Message Service (JMS) 1.0.2b compliant
Support for routing P2P JXTA interactions.
Grid Feature Support
NaradaBrokering enhanced Grid-FTP. Bridge toGlobus GT3.
Web Service reliability
Prototype implementation of WS-ReliableMessaging
Forthcoming Features
• Production implementations of WS-Eventing,
WS-Notification, WS-RM and WS-Reliability.
• Time Differential Services: Preserve time
spacing between events, that are time-stamped
using high-resolution timers.
• Active replay support: Pause and Replay live
streams.
• Replicated storage support for fault tolerance
and resiliency to storage failures.
NaradaBrokering and IOI
• “Software Overlay Network” features
• Support for Multiple Transport protocols
• Support for multiple delivery mechanisms
– Reliable Delivery
– Exactly-once Delivery
– Ordered Delivery
– Optional Delivery optimization modules for different modes
• Compression/Decompression of payloads with optional module
• Coalescing/Fragmentation of payloads with optional module
• NTP Time Service
• Security Service
• Performance Monitoring
• Performance optimized routing with optional module
• Support for WS-Reliability, WS-ReliableMessaging and their
Federation
Virtualizing Communication



Communication specified in terms of user goal and Quality of
Service – not in choice of port number and protocol
Bit Internet 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 “Service Internet” communication can involve multiple
transport protocols and multiple destinations – the latter
possibly determined dynamically
NB Brokers
A
Satellite
UDP
Firewall
HTTP
Software Multicast
NB Broker
Client Filtering
Fast
Link
B1
Hand-Held
Protocol
Dial-up
Filter
B2
B3
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
Broker
Broker
Monitoring
intervals can
Node
Node
Service
also be varied
Link
Link
Monitoring Service,
Data
Data
returns measured
Aggregates info
metrics to
Control Message
from nodes in a
Exchange
Performance
certain domain
Aggregator.
Performance Aggregation
Service
Transit Delay (Milliseconds)
Mean transit delay for message samples in
NaradaBrokering: Different communication hops
9
8
7
6
5
4
3
2
1
0
hop-2
hop-3
hop-5
hop-7
100
1000
Message Payload Size (Bytes)
Pentium-3, 1GHz,
256 MB RAM
100 Mbps LAN
JRE 1.3 Linux
Standard Deviation for message samples in NaradaBrokering
Different communication hops - Internal Machines
0.8
hop-2
hop-3
hop-5
hop-7
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1000
1500
2000
2500
3000
3500
Message Payload Size
(Bytes)
4000
4500
5000
Custom Message Reliability
2 second PDA reply latency!
Different endpoints may
well need different
reliability schemes.
Another reason to use
application layer.
Need to define easy to
use “standard reliability
profiles
Wireless
Optimized
WS-RM
Filter 2
Narada
Broker
WS-Reliability
Filter 1
WS-RM
NaradaBrokering and Fault Tolerance
• As well as reliable messaging, NaradaBrokering supports
performance based dynamic routing
– Choose both route and protocol (UDP, Parallel TCP ..)
• It will also support automatic fail-over among replicated
services subscribing to same message stream
• Provides scriptable control of streams for custom
management schemes
• Saves ALL messages in fault
tolerant storage for either
session replay or recovery
• Will support reliable BitTorrent
P2P file swapping model
(better than GridFTP?)
GridFTP plus NaradaBrokering
Fast Web Service Communication I
• IOI Application level Internet allows one to optimize
message streams at the cost of “startup time”, Web Services
can deliver the fastest possible interconnections with or
without reliable messaging
• Typical results from Grossman (UIC) comparing Slow
SOAP over TCP with binary and UDP transport (latter gains
a factor of 1000)
Record
Count
SOAP/XML
Pure SOAP
WS-DMX/ASCII
SOAP
over UDP
WS-DMX/Binary
Binary
over UDP
MB
µ
σ/µ
MB
µ
σ/µ
MB
µ
σ/µ
10000
50000
150000
375000
1000000
5000000
0.93
4.65
13.9
34.9
93
465
2.04
8.21
26.4
75.4
278
7020
7020
6.45%
1.57%
0.30%
0.25%
0.11%
2.23%
0.5
2.4
7.2
18
48
242
1.47
1.79
2.09
3.08
3.88
8.45
0.61%
0.50%
0.62%
0.29%
1.73%
6.92%
0.28
1.4
4.2
10.5
28
140
1.45
1.63
1.94
2.11
3.32
5.60
5.60
0.38%
0.27%
0.85%
1.11%
0.25%
8.12%
Fast Web Service Communication II
• Mechanism only works for streams – sets of related
messages
• SOAP header in streams is constant except for
sequence number (Message ID), time-stamp ..
• One needs two types of new Web Service
Specification
• “WS-StreamNegotiation” to define how one can use
WS-Policy to send messages at start of a stream to
define the methodology for treating remaining
messages in stream
• “WS-FlexibleRepresentation” to define new
encodings of messages
Fast Web Service Communication III
• Then use “WS-StreamNegotiation” to negotiate stream in
Tortoise SOAP – ASCII XML over HTTP and TCP –
– Deposit basic SOAP header through connection – it is part of
context for stream (linking of 2 services)
– Agree on firewall penetration, reliability mechanism, binary
representation and fast transport protocol
– Naturally transport UDP plus WS-RM
• Use “WS-FlexibleRepresentation” to define encoding of a Fast
transport (On a different port) with messages just having
“FlexibleRepresentationContextToken”, Sequence Number,
Time stamp if needed
– RTP packets have essentially this structure
– Could add stream termination status
• Can monitor and control with original negotiation stream
• Can generate different streams optimized for different end-points
Grids and e-globalcommunity

Peer-to-peer networks already are a good example of
value of Information Technology supporting broad
global communities
• File sharing, text chats, bulletin boards



Grids must include these capabilities and extend in
terms of increased functionality and quality of service
This will support business and cultural interactions
between nations
Several interesting applications can be supported by
• Replacing files by multi-media streams so can collaborate in
real-time
• Adding traditional tools like audio-video conferencing and
shared applications to P2P set

This integration of P2P and Grid to give M2 Grids
impacts e-Business as well as e-globalcommunity
Streaming







2
M
Grids
e-Textilemanufacturing involves Clothes designers in USA and
manufacturers in Hong Kong exchanging designs which are
streams of images
e-Sports is a possible collaboration between Indiana University and
Beijing Sport University
• Basket ball coaches (teacher) interact with aspiring NBA players
in China
• Martial Arts masters in China train neophytes in Indiana
• Faculty recreational sports adviser works from university with
faculty exercising at home
• Hope to have working incredibly well by the 2008 Olympics
Interactive TV Grid: allows anybody to discuss professional or
home video (of sports or other events) within a custom Grid
Multi-player distributed games which should be supported with
exactly the same overlay Grid
Video Game Production Grid links artistic direction (design) in one
country with digital animation (manufacturing) in another
e-Science: Physics and Environmental Science Sensors
Surveillance Grid enables security personnel to annotate and
discuss suspicious remote camera images/streams
Some Technology for Streaming M2 Grids





Basic capability is collaborative annotatable multimedia
tool for images, sensors and real-time video streams
• Allow Grid participants to view real-time streams,
rewind on the fly and add text and graphical
comments
• Similar to instant replay on TV but far more flexible
Need rich metadata system to label and correlate streams,
images and annotations
Extend Grid and P2P file access paradigms to stream
storage, browsing and access
Core Technologies shared with distance education
Using http://www.globalmmcs.org for multimedia
services and http://www.naradabrokering.org for overlay
network
P2P and Server based solutions


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Peer-to-peer architectures have advantage that they can be deployed
just using client resources and no system commitment is needed
Typically clients do not have good network QoS and it is hard for
example to support rich multi-point audio video conferencing in this
way
M2 Grids typically require multicast so average load in P2P case on
client legs goes like O(M)
Grid
Farm
in theload
Sky on
(clouds)
• Server-side multicast
puts
O(M)
backbone and O(1) load
on clients and can lead to much better scaling and performance
• N plus N Grids may not see such large improvements with server
Grid Servers
side support
So Grids should support initial P2P deployment with a seamless
upgrade to add better QoS using Servers.
Extend familiar P2P paradigms like BitTorrent to Grids and
Streaming
P2P
Grid and peer-to-peer linkage combines scalable performance with
ease of deployment
CIE: Common Service Information and Metadata
• Consider a collection of services working together
– Workflow tells you how to specify service interaction but more
basically there is shared information or context
specifying/controlling collection
• WS-RF and WS-GAF have different approaches to contextualization –
supplying a common “context” which at its simplest is a token to
represent state
• More generally core shared information includes dynamic service
metadata and the equivalent of configuration information.
• One can supports such a common context either as pool of messages
or as message-based access to a “database” (Context Service)
• Two services linked by a stream are perhaps simplest example of a
collection of services needing context
• Note that there is a tension between storing metadata in messages and
services.
– This is shared versus distributed memory debate in parallel
computing
Stateful Interactions
• There are (at least) four approaches to specifying
state
– OGSI use factories to generate separate services for each
session in standard distributed object fashion
– Globus GT-4 and WSRF use metadata of a resource to
identify state associated with particular session
– WS-GAF uses WS-Context to provide abstract context
defining state. Has strength and weakness that reveals less
about nature of session
– WS-I+ “Pure Web Service” leaves state specification the
application – e.g. put a context in the SOAP body
• I think we should smile and write a great metadata
service hiding all these different models for state and
metadata
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, audiovideo 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 update events of all
kinds as message streams
Need publish/subscribe approach to share messages (NB) plus
System to control “session” – who is collaborating and rules
• XGSP is XML protocol for controlling collaboration building
on H323 and SIP
XGSP Web Service MCU Architecture
Use Multiple Media servers to scale to many codecs and many
versions of audio/video mixing
Session Server
XGSP-based Control
NaradaBrokering
All Messaging
NB Scales as
distributed
Admire
Web
Services
SIP
H323
Media Servers
Filters
High Performance (RTP)
and XML/SOAP and ..
Access Grid
Gateways convert to uniform XGSP Messaging
NaradaBrokering
Native XGSP
Global-MMCS Community Grid




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.
The function of A/V media server is 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
• Java Media Framework basis of Media Servers
• Helix Community http://www.helixcommunity.org for Real
Media
http://www.globalmmcs.org open source “non advertised”
release
Break up into Web Services

Monolithic MCU becomes many different “Simple Services”
•
•
•
•
•
•
•
•



Session Control
Thumbnail “image” grabber
Audio Mixer
Video Mixer
Codec Conversion
Helix Real Streaming
PDA Conversion
H323/SIP Gateways
As independent can replicate particular services as needed
• Codec conversion might require 20 services for 20 streams
spread over 5 machines
1000 simultaneous users could require:
• 1 session controller, 1 audio mixer, 10 video mixers, 20 codec
converters, 2 PDA converters and 20 NaradaBrokers
Support with a stream optimized Grid Farm in the sky
• Future billion way “Video over IP” serving 3G Phones and home media
centers/TV’s could require a lot of computing
GlobalMMCS and NaradaBrokering

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


All communication – both control and “binary” codecs are
handled by NaradaBrokering
Control uses SOAP and codecs use RTP transport
Each stream is regarded as a “topic” for NB
Each RTP packet from this stream is regarded as an “event” for
this topic
Can use replay and persistency support in NB to support
archiving and late clients
Can build customized stream management to administer replay,
and who gets what stream in what codec
NaradaBrokering supports unicast and multicast
Use firewall penetration and network monitoring services in NB
to improve Q0S
Average Audio Delays
Latency
Latency
# Clients
AUDIO PERFORMANCE
10
20
40 per session
Audio Scaling
Multi Sessions
1 Transmitter
Latency ms
One Session
Multi Sessions
Multi Transmitters
# Receivers
Average Video Delays`
Latency
Multiple
sessions
One session
# Receivers
Packets per Frame
Frame #
Latency
500 receivers
Packet Size Bytes
Effect
of
Packet
Size
Polycom, Access Grid
and RealVideo views of
video-mixed streams
using GlobalMMCS
Integration of PDA, Cell phone and Desktop Grid Access
NB Support for optimized
PDA Communication