Transcript Principles for Collaboration Systems

Principles for Collaboration
Systems
Geoffrey Fox
Community Grids Laboratory
Indiana University
Bloomington IN 47404
[email protected]
Requirements or Issues to be Addressed I
• Interoperability: Several standards – e.g. H323,
T120, SIP, Access Grid – which are inconsistent with
themselves and with modern Web standards
• Integration: Integrate all forms of collaboration –
instant messenger, audio-video conferencing,
application sharing
• Life-cycle costs: use commodity software
components
• Extensibility: Interfaces defined for adding new
capabilities
• Legacy: Support existing relevant infrastructure
• Network Quality of Service: communication links are
dynamic and of variable quality and bandwidth.
Requirements or Issues to be Addressed II
• Performance: Allow maximum performance with
given network with no unnecessary client or server
overheads
• Fault Tolerance: Fault tolerant session control
• Security: Support multiple levels of security for
clients, servers and communication traffic
• Scalability: Current systems are often limited by
architecture or implementation (such as a single
server) in number of simultaneous participants
• Pervasive Access: Need to support wide range of
clients from hand-held devices to sophisticated
desktop system.
• Ease of Use: Simple web portal interface; no special
hardware
• Archiving: Universal mechanism for archiving
collaborative session
Collaboration Architecture
• Use Grid and Web Service base architecture
• Define XML-based Collaboration Interface specification
capturing semantics of existing standards
• Define open interfaces allowing both third party services to be
developed and to allow competitive implementation of base
infrastructure
• Use software overlay network to support needed dynamic
routing and message-based architecture
• Use active measurements to find network performance and
network or server/broker faults
• Use Web Service message based security
• Use publish/subscribe paradigm for all messaging to support
multi-participant sessions and archiving
• Use distributed scalable fault-tolerant middleware including
WS-RM (Web Service Reliable Messaging) or equivalent
Match of Requirements to Architecture I
• Interoperability: Can build services mapping
betweens codecs and other architectures
• Integration: Overlay network supports all protocols
and web service collaboration model supports all
applications
• Life-cycle costs: Totally based on commodity web
service architectures
• Extensibility: Framework for adding services defined
in Web service standard fashion
• Legacy: Can build gateways of existing systems as
Services and can interface with existing clients and
• Network Quality of Service: supplied by overlay
network and dynamic performance/fault detection
Match of Requirements to Architecture II
• Performance: Commodity server overhead negligible
compared to network transit time so can realize full
performance allowed by communication channels
• Fault Tolerance: WS-RM and redundant distributed brokers
and server fault detection
• Security: WS-Security gives standard compliant security with
message-based security which is preferable to conventional
connection based approach
• Scalability: Distributed Overlay Network Broker with dynamic
servers has no scaling limit other than that of network
• Pervasive Access: Service model allows filters to drive any
client with well defined interfaces
• Ease of Use: Web service infrastructure naturally supported by
pervasive Web interfaces
• Archiving: Publish/subscribe architecture allows general
archive to subscribe to all or part of a session
GlobalMMCS and Anabas Technology
• Prototypes using proposed architecture have been developed
by Indiana University in an open source project and
commercially by Anabas
• NaradaBrokering is open source publish/subscribe overlay
network messaging system
– Has performance monitoring driving dynamic routing
– WS-RM reliability and WS-Security secure messages
– Distributed brokers support full scalability
• XGSP is XML session protocol capturing H323 SIP and Access
Grid Semantics – Gateways allow systems using these
protocols to interoperate
• Web service middleware with sample services including PDA
interface, codec conversion and media mixing
• Anabas supports text chat, shared display application while
GlobalMMCS supports audio/video conferencing