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This document outlines essential requirements and solutions for building robust collaborative systems, including interoperability, integration, and scalability. It highlights the significance of using commodity software, dynamic routing, and message-based security while accommodating various clients from mobile to sophisticated desktop systems. Key aspects include fault tolerance, multiple security levels, ease of use, and archiving capabilities. The proposed architecture leverages web services and open interfaces, ensuring extensibility and allowing existing infrastructures to participate seamlessly, enabling better collaboration across diverse applications.
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Principles for Collaboration Systems Geoffrey Fox Community Grids Laboratory Indiana University Bloomington IN 47404 gcf@indiana.edu
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