Architecture

1
Architecture Performance

• Community Place case study
• Presented by
• u4068413
• Jin Hyung, SEO

2
Contents

• Introduction
• Architectural Possibilities
• Basic CP System
• Server Scalability
• Architectural features of current CP
• Performance Issue
• Distributed Architecture
• Conclusion

3
Introduction

• Aim infrastructure that will allow many users
  to participate in a shared, interactive 3D world
• Large scale system capable of supporting many
  geographically dispersed users, interconnected
  through low bandwidth, high latency communication
  links

4
Possible System Architecture

• ClientServer Architectures simplest method of
  building a distributed system
• Peer to Peer Systems each client maintains a
  copy of data
• Hybrid Systems merge client-server and peer to
  peer model

5
CP System Architecture ?
Application Object (AO)
WWW server (httpd)
VSAP
Server Manager Dynamic data
HTTP
VSCP
VSCP
WWW browser
CP browser
WWW browser
CP browser
Client System (PC)
Client System (PC)
Basic CP Architecture
6
CP System Architecture ?

• Browser
• Works in conjunction with a HTML browser
• Loads the 3D data file (in VRML 2.0 format)
• Contacts the server via the VSCP that runs above
  IP
• CP browser supports the VRML2.0 standard and uses
  Java as its scripting language
• Browser-server communication
• VSCP (Virtual Society Communication Protocol)
• Efficient communication of 3D scene
  transformation
• Open-ended support for script specific message

7
CP System Architecture ?

• Server
• Position tracker and message forwarder
• Role
• Manage the state of Object on behalf of connected
  users
• Carry out a similar function for any script level
  messages that are generated by a browser as a
  result of user interaction

8
Application Programming Models ?

• SSS (Simple Shared Script) Model
• Small shared applications in the 3D world
• Master browser
• AO (Application Object) Model
• More complicated application
• VSAP (Virtual Society Application Protocol)
• Dynamic addition of VRML data and associated
  scripts to an existing scene
• Commercial environment

9
Application Programming Models ?
4
Application Object (AO)
Server Aura Manager Dynamic data
Server Aura Manager Dynamic data
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4
5
1
3
2
5
5
6
2
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CP Browser
CP Browser
CP Browser
CP Browser
Simple Shared Script
Application Object
10
Scaleability

• For scalability in large application.
• Static scene data is downloaded initially as part
  of the VRML file while dynamic data can be
  managed using local scripts plus message passing
• Offload some processing into the client browser
  using the local scripting facility
• Sophisticated applications can be managed by
  external processes and can use the local script
  to manage local updates in individual browsers
• Limit the number of messages needed between
  browsers

11
Spatial Areas of Interest

• Area of application can be divided into several
  groups
• Aura manager is responsible for defining groups
  of spatially co-located objects
• Each objects in the same group are maintained
  consistent together

12
Feature of CP Architecture

• Total state of the shared VRML scene is split
  between VRML data managed at the clients and data
  managed by the server since server is responsible
  for maintaining the location and some attribute
  data belong to client (exgt avatar data)
• By pushing data out to clients
• Reduce server load
• Increase performance

13
Server Performance ?
Sun Sparc
SGI Indigo2
Sony NEWS
Server
Sony workstation
Client
Server Performance Experiment Environment
14
Server Performance ?

• CPU load with the number of connection
• Sony and SGI are comparable and Sun 10 more
  powerful
• At 30 CPU idle time, Sony - 400 connections, SGI
  - 425 connections while Sun - 520 connections
• Network Traffic
• Sony SGI support a maximum 500 connections
  before network performance tails off while Sun
  does almost 630 connection
• AURASIZE MAXINAURA
• Increasing the MAXINAURA will lead to a growth in
  traffic
• The interplay with the AURASIZE is less clear

15
Browser Performance

• Event processing cost within the browser
• cost of this execution path is 0.99 ms (averaged
  over 3000 runs)
• Cost of basic networking function
• average cost of 6.48 ms (repeated 3000 times)
• Application message cost
• SSS model is more costly and sensitive to server
  load

16
Distributed Architecture ?
Multicast based Group comms.
User 3
WWW browser
CP browser
VSCP
Client System (PC)
VSCP
User 2
WWW browser
CP browser
VSCP
Replica of Data item
User 1
WWW browser
CP browser
Client System (PC)
Master copy Of data item
Client System (PC)
17
Distributed Architecture ?

• Spatial model is used exactly as in the single
  server case
• It partitions the database into groups of
  spatially co-located objects who manage their
  consistency using a group communication model

18
Conclusion

• Most important goal of the CP project has been to
  provide an infrastructure that allows easy
  creation of such spaces, within a familiar
  framework, the WWW
• Scaling and performance issue should be always
  considered to support large numbers of users and
  more complicated scenes

19
Related Works

• WWW and using full 3D shared space
• Cybergate system (Blacksun Inc.)
• Moondo
• Pueblo Project (Chaco Communication)

20
Q A