A Framework for Dynamically Configurable Multimedia Distribution

1
A Framework for Dynamically Configurable
Multimedia Distribution

• Fabio Kon and Roy H. Campbell
• Department of Computer Science
• University of Illinois at Urbana-Champaign
• http//choices.cs.uiuc.edu

2
Introduction

• Multimedia interfaces are becoming increasingly
  important.
• Future systems will abandon dull interfaces based
  on text and still images.
• Video, audio, and animations will prevail.
• TV and Radio broadcasting systems will join the
  network.

3
Problems with Multimedia Streaming Technology

• Existing MBone and unicast solutions do not
  provide good levels of
• Control
• Flexibility
• Scalability
• Quality of Service Management

4
Previous Work

• Object-Oriented Multimedia Distribution System in
  C KCT98.
• Multimedia Reflectors work as relays.
• Network of Reflectors can be remotely
• reconfigured
• monitored
• Decentralized administration.

5
A Reflector Network
6
The Multimedia Reflector

• Applications
• Live Multimedia Streaming
• Stored Content Streaming
• Audio/Videoconference
• Multiple Channels
• Multiple Input and Output connections

7
Data Distribution Protocols

• C abstract class Connection
• open()
• close()
• Bind()
• Connect()
• Send()
• Receive()
• Bandwidth Control

• Subclasses
• UDPConnection
• TCPConnection
• MulticastConnection
• Most of Reflectors code deals only with the
  abstract class.

8
Experimentation(First Round)

• Live video from NASAs Pathfinder Mission
• 3 months
• gt 30 reflectors in 5 continents
• gt 1 million video sessions
• Java Applet decoding 24kbps of
• H.263 video
• GSM audio

9
Problems Encountered

• 1. Code update
• Bug fixes and new versions.
• i. Manually FTP new code to host machine
• ii. Telnet to host machine
• a. Shutdown existing version
• b. Start new version
• Repeat this dozens of times

10
Problems Encountered

• 2. Dynamic Reconfiguration
• Channels, in/out connections, max of clients.
• Configuration information was kept in a
  centralized location.
• A. Update the configuration database.
• B. Connect to each Reflector and instruct it to
  download the new configuration.
• Tiresome and error prone.

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Problems Encountered

• 3. Fault-Tolerance
• Supported with redundant streams ? Extreme waste
  of bandwidth.
• Solution
• Use Infrastructure offered by dynamicTAO, a
  dynamically configurable CORBA ORB.

12
Solution

• Wrap the Reflector with a CORBA IDL interface.
• dynamicTAO, CORBA ORB extended with a
  reconfiguration meta-interface to allow
• 1. Uploading executable code.
• 2. Dynamically load components into the runtime.
• 3. Change configuration parameters of
  applications.
• 4. Modify internal structure of component-based
  apps.

13
Reconfiguration Agents

• SysAdmins use a GUI to build agents for
• reconfiguration
• inspection
• GUI is used to
• 1. Build distribution graph
• 2. Select reconfiguration and inspection commands
• 3. Visualize results.

14
Reconfiguration Agents

• Code uploading example
• upload_impl Connection UDPCon
• load_impl Connection UDPCon
• hook_impl gtConnection Reflector UDPConnection
• Reconfiguration example
• configure_impl Reflector MAX_NUM_CLIENTS200

15
Fault-Tolerance

• Goal maximize availability without relying on
  redundant data transmission.
• Solution
• The Reflector maintains a list of alternate
  inputs for each of its channels.
• If a Reflector dies, first it tries to inform its
  neighbors.
• Input silent for too long ? switch to another
  one.

16
Representing Inter-Component Dependence

• ComponentConfigurator framework
• Implementations in C, Java, and CORBA

17
Implementation Status

• Completed
• Non-CORBA version of the Reflector
• dynamicTAO and infrastructure for reconfiguration
  agents
• Working on
• CORBA wrapper for the Reflector
• Breaking Reflector code into dynamically loadable
  components
• Fault-tolerance with the help of the
  ComponentConfigurator Framework

18
Future Work

• Automatic Management of data flows to
• minimize user delays
• optimize network utilization
• support load balancing
• Integrate with CORBA Naming and Trading Services

19
Related Work

• White Pines Multipoint Control Unit for Meeting
  Point (proprietary protocols for reconfiguration,
  no code updates).
• Our system can be seen as
• an extension to the idea of the MBone, or
• a set of tools for managing MBone broadcasts.

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Conclusions

• Internet Multimedia Distribution Systems will
  replace existing Radio and TV networks.
• But first, they must provide high levels of
  flexibility, configurability, and scalability.
• Our design builds on OO Frameworks, CORBA, mobile
  agents, and dependence representation.
• Not limited to Multimedia.
• These methods can be applied in any large,
  distributed component-based system.

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For More Information...

• dynamicTAO web site
• http//choices.cs.uiuc.edu/2K/dynamicTAO
• ComponentConfigurator source code and
  documentation
• http//choices.cs.uiuc.edu/2K/ComponentConfigurato
  r
• E-Mail f-kon_at_cs.uiuc.edu