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Evaluating Collaborative Infrastructure for CSCW Apps Grid/Web Services. COMP 790, Fall 2006 Collaborative Systems. References. CoFrame: A framework for CSCW Applications based on Grid and Web Services

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evaluating collaborative infrastructure for cscw apps grid web services

Evaluating Collaborative Infrastructure for CSCW AppsGrid/Web Services

COMP 790, Fall 2006

Collaborative Systems

references
References
  • CoFrame: A framework for CSCW Applications based on Grid and Web Services
    • Jinlei Jiang et al, Proceedings of IEEE International Conference on Web Services (ICWS 2005)
  • Developing Collaborative Editing Applications using Web Services
    • Muhammad Younas, Rahat Iqbal, Coventry University, Coventry, UK
  • Improving Network Efficiency in Real-Time Groupware with General Message Compression
    • Carl Gutwin et al CSCW 2006
  • A Collaborative Infrastructure for Aerospace Design
    • http://ic.arc.nasa.gov/people/filman/text/darwin/ace.pdf
  • A Collaborative Infrastructure for IM applications
    • http://www.imlogic.com/
  • A Collaborative Infrastructure for Scalable and Robust News Delivery
    • http://doi.ieeecomputersociety.org/10.1109/ICDCSW.2002.1030843
collaborative infrastructure
Collaborative Infrastructure
  • CSCW Applications and Infrastructure
    • Are they the same ?
  • What is a CSCW Application:
    • N-user software
    • Example: Chat Tool
cscw infrastructure
CSCW Infrastructure
  • Higher Level of abstraction that provides application developers a framework to build CSCW applications.
  • Example:
    • We have already used one:
    • “Sync”: A Java based framework for

developing collaborative

applications

features supported flexibility
Features Supported / Flexibility
  • NewsWire collaborative content delivery system
    • Deals with real-time delivery of news items
    • Reduces Compute/Network load
  • DARWIN
    • Collab Infrastructure for AeroSpace Design
      • Issues such as: wind tunnel testing data
    • Focus:
      • Storing/Indexing data
      • Manage visualizations for stored/derived data
  • IMLogic
    • IM Application development infrastructure
  • Drawbacks
    • Specific to one application.
    • Deal with some core issues but not all
  • Alternatives:
    • Sync (Framework for Collaborative Applications)
    • Web Services and Grid Computing
features supported grid web
Features supported – Grid/Web
  • Provide Core Services and additional services
    • Core Services:
      • Communication
        • Cooperative Message Bus (CMB)
        • RMI (Sync Equivalent)
        • SOAP (Simple Object Access Protocol)
    • Additional Services:
      • Process Management Service
      • Awareness Support Service
      • Interaction-Aided Service
        • Directory Service
          • UDDI (Universal, Description, Discovery and Integration)
          • Central Registry (similar to UDDI)
          • RMI registry (Sync)
        • Persistence Visual Cooperation space facility
  • Easier to add new functionality as it gets added as another service in the framework
programming model environment
Programming Model (Environment)
  • Grid Computing
    • Use existing infrastructure to manage data, resources and to collaborate to solve a large scale problem.
    • Use multiple computer (resources) to build a Virtual computer architecture
    • Open unlike Sync (closed)
programming model environment1
Programming Model (Environment)
  • Scalability
    • Firewalls
  • Description of Services:
    • CoFrame: WSDL (Web Services Description Language)
    • Sync: Java
  • Coding Language
    • CoFrame
    • Sync
  • Globus Toolkit 3
    • OpenSource
    • Industry Standard
programming cost transparency
Programming Cost (Transparency)
  • Developers need to only concern themselves with services being offered and not how the services are implemented.
  • CoFrame Architecture:
    • Grid layer separates Application layer from Resource layer
    • Younas/Iqbal doesn’t provide such an abstraction.
    • Sync (Integrated RMI)
consistency of data
Consistency of Data
  • Younis/Iqbal propose a transaction based model similar to ACID concepts
  • ACID (Atomic, Consistent, Isolated, Durable)
  • SACReD
  • CoFrame doesn’t mention Consistency of data but the SACReD approach can be implemented in the CMB part of the framework
fault tolerance
Fault Tolerance
  • Central server easier to secure (one point of failure)
    • Grid Architecture (Distributed)
    • CoFrame provides for:
      • Single Sign On Service
resource optimization
Resource Optimization
  • Bottleneck : Network Bandwidth and Latency
    • Effects:
      • Deterioration of user experience
    • Example:
      • Video Chat with video frame updating every two seconds
  • How to Fix this:
      • Improve resources
        • Better network layout
      • Optimize current resources
        • Message Compression
        • Resource Replication Policy
resource optimization message compression
Resource Optimization:“Message Compression”
  • Why Needed ?
    • Collaborative applications share a lot of data.
    • Inter-collaborative application messages
    • Example:
      • Dragging a window across screen
        • Updates need to be sent consistently to all connected clients
    • Use of XML
    • Message must include:
      • Sender id, message id, application id, timestamp, message type, fieldnames and data values corresponding to each field
  • Send messages less frequently ?
  • Encoding before sending, decoding on receiving
    • Gutwin proposes a mix of Ziv-lempel algorithm, Huffman

Coding and building a dictionary of sequences with short lookup

codes.

message compression
Message Compression
  • Sources of Inefficiency in Groupware messages
    • Repetition Within a single message
    • Repetition between messages
    • Inefficient Coding
      • Encoding of numbers.
      • Field widths for numeric data types.
message compression algorithm
Message Compression - Algorithm
  • Within-Message Issues:
    • Use standard zlib algorithm
      • Helpful when sending large messages
  • Between-messages Compression
    • Treat one message as template
    • Compare subsequent against that template, to determine repeated sequences
    • Replace repeated sequences by codes in a

dictionary

    • Create new templates if messages not similar
resource replication
Resource Replication
  • Replication of resource
    • Backup of Data
    • More optimized – can serve from best source
  • Centralization of resource
    • Easier to implement
  • Grids are distributed in nature
    • Replication model proposed by CoFrame
resource replication1
Resource Replication
  • Resources stored independent of working nodes
  • Provider publishes to one server
    • Broadcast message using CMB to store metadata
heterogeneous systems
Heterogeneous Systems
  • CSCW Application built for different resources
    • Example: Two collaborators (A & B) connected using two different devices
    • A has good Network (Cable/DSL) while B is on a relatively poor network (Dialup)
    • Both on a Video Chat or using a 3D graphics application
  • Compression of data
  • Lower bit-rate