What You Need Is What You Get: Automatic Configuration in

1
What You Need Is What You GetAutomatic
Configuration in

• Fabio Kon
• advisor Roy H. Campbell
• Department of Computer Science
• University of Illinois at Urbana-Champaign

2
Introduction

• Component-Based Technology
• Building complex applications from off-the-shelf
  Components
• Recent Technologies
• ActiveX Controls
• Enterprise Java Beans
• CORBA Component Model

3
Problem

• Little or no support for managing
  Inter-component Dependencies.
• Components are created by different groups w/
  different methodologies
• Systems are not reliable.
• Difficult to support fault-tolerance.
• Difficult to support dynamic reconfiguration.
• Too many components added to the system.

4
The 2K Distributed (meta-)Operating System

• 2K is able to run
• on top of existing Oses (UNIX, WINDOWS)
• on our customized microkernel
• Based on CORBA components
• Automatic Configuration (WYNIWYG)
• Dynamic Reconfiguration (adaptation)
• Network-Centric
• QoS-Aware Resource Management

5
Proposed Solution

• OS and/or middleware must manage component
  dependencies.
• Represent component dependence explicitly.
• Two kinds of inter-component dependence
• Prerequisites
• Dynamic Runtime Dependence
• Use them to support Automatic Configuration

6
Prerequisites

• What a component needs to run
• nature of hardware resources
• share of the hardware resources
• software services (i.e., components) it requires
• Video Client example
• PC with MPEG decoding card
• 50 of 200MHZ CPU
• CORBA Video Service

7
Handling Prerequisitesin 2K
8
CORBA Prerequisite Parser

• Prerequisite can be
• 1.Name in the 2K Implementation Repository
• 2.ServiceTypeName and Constraint for the CORBA
  Trading Service.
• 3.Component IOR (i.e., CORBA reference)

9
Simple Prerequisite Description Format (SPDF)

• hardware requirements
• machine_type SPARC
• native_os Solaris
• min_ram 5MB
• optimal_ram 40MB
• min_vm 30MB
• optimal_vm 40MB
• software requirements
• FileSystem /sys/storage/DFS1.0 (optional)
• TCPNetworking /sys/networking/BSD-sockets
• WindowManager /sys/WinManagers/simpleWin
• JVM /interp/Java/jvm1.2 (optional)

10
Prerequisite Resolver

• Cached Pull-based Policy
• 1. Locate prerequisite in the local machine
• 2. If not present, contacts Implementation
  Repository or Trader.
• The cache is a local repository of component
  implementations and IORs.

11
Dynamic Runtime Dependence

• Stores dynamic inter-component dependencies.
• Created on-the-fly by the Prerequisite Resolver.
• Dependence graph can be modified by system and
  application components.

12
ComponentConfiguratorFramework
13
Dynamic Reconfiguration
14
Related Work(in Operating Systems)

• Customizable OSes
• Choices, Exokernel
• Microkernels
• Mach, SPIN, MicroChoices, L4

15
Related Work(in Dynamic Configuration)

• Emphasis on overall application architecture
• Software buses (POLYLITH)
• Software Architecture
• Architecture Description Languages
• Emphasis on dependencies
• the OS is also component-based and adaptable
• dynamic (runtime) reconfiguration
• Resource management

16
Implementation Status

• Completed Prototypes of
• Dynamically Configurable CORBA ORB (dynamicTAO).
• Automatic Configuration Service with SPDF.
• Monitoring Service.
• Dynamic Security Service.
• Persistent Object Service.
• Minimal ORB for small devices (LegORB).

17
Conclusions

• Component technologies must be aware of component
  dependencies.
• Middleware-based dependence management can make
  systems
• easier to administer
• automatically configurable
• more reliable
• dynamically adaptable

18
How to contact us

• 2K Web site
• http//choices.cs.uiuc.edu/2K
• my E-mail f-kon_at_cs.uiuc.edu

19
Updating the JVM

• int WebBrowserConfiguratoreventOnHookedComponent
  
• (ComponentConfigurator cc, Event
  e)
• if (cc JVMConfigurator)
• if (e REPLACED)
• try
• FrozenObjs fo currentJVM-gtfreezeAllObjs
  ()
• currentJVM JVMConfigurator-gtimplementation
  ()
• currentJVM-gtmeltObjects (fo)
• catch (Exception exp)
• throw new ReconfigurationFailed(exp)
• else ...

20
Application Multimedia Distribution
21
The Multimedia Reflector

• Applications
• Live Multimedia Streaming
• Stored Content Streaming
• Audio/Videoconference
• Multiple Channels
• Multiple input and output Connections
• Multiple Connection types

22
Applying the Framework

• Prerequisites
• used to customize the components of each
  Reflector
• Resource reservation (memory and CPU)
• ComponentConfigurators
• represent inter-Reflector dependencies
• support fault-tolerance