ChorusOS Sun Microsystems Operating System --------------------------------------------------------------------------

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ChorusOSSun Microsystems Operating
System-------------------------------------------
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• Java Based OS

Hemalkumar Doshi Instructor Dr. Marius Soneru
Course CS 550 Comparative Operating Systems
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Overview-----------------------------------------
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• History of the ChorusOS
• Goals of ChorusOS
• ChorusOS Abstraction
• ChorusOS Operating System Kernel
• Product Components
• ChorusOS Layers
• How Chorus is Used in a Distributed System
• Features and Benefits of ChorusOS
• Chorus Application Overview
• Conclusion

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History of the ChorusOS--------------------------
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• Originally developed as French research project
• Bought by Sun Microsystems in 1997
• V0 collection of actors
• V1 French SM90 Multiprocessor Ethernet
• V2 Move to Micro-kernel
• V3 Sun bought RPC implemented

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Goals of Chorus----------------------------------
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• Enhancement of Unix
• Dynamically Loadable Servers
• Real Time Operations
• Improve network communication
• Portability

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ChorusOS Abstraction-----------------------------
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• Actor is an execution environment.It can have
  one or more thread
• Ports is an unidirectional communication channel
  with an associated message queue. Ports can be
  migrated between actors.
• Port groups Ports can be made members of port
  groups. A port group is a destination for
  messages, and there are several addressing modes
  for sending messages to a port group.
• Messages A Chorus message consists of a variable
  length body (limited to 64 kilobytes), and
  optionally a fixed-size (64-byte) header.
• Regions, segments and local caches An actors
  address space is divided into regions. A region
  can be mapped onto a portion of a Segment. For
  each mapped segment the kernel keeps a local
  cache.

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ChorusOS Operating System Kernel----------------
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--------
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Product Components-------------------------------
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• Core Executive
• Support for Multiple Independent Applications.
• Support for user and system applications
• Support for applications in user and supervisor
  address space
• Dynamic Memory Management

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Product Components Cont-------------------------
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• Schedulers
• Real-time scheduler
• Priority-based, pre-emptive FIFO
• Multi-class scheduler
• Priority-based, pre-emptive FIFO
• Priority-based with fixed-time quantum
• User defined policy

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Product Components Cont-------------------------
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• Communications
• Local IPC Single-board, asynchronous,
  synchronous, and multicast communication
• Distributed IPC Location-transparent extension
  to multiple IPC communication sites
• Real-time message queues
• Shared memory

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Product Components Cont-------------------------
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• Memory Management
• Flat memory Management of physical memory, no
  protection
• Protected memory Multiple protected address
  spaces
• Virtual memory Page-based protected address
  spaces, optional on-demand paging

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Product Components Cont

• Synchronization
• Semaphores
• Mutexes
• Event flags

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Product Components Cont

• Time Services
• Timers One-shot or periodic, usable from both
  supervisor and user-mode applications
• Time of day Universal time
• Real Time Clock (RTC)

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ChorusOS Layers----------------------------------
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UNIX Subsystem
Object-Oriented subsystem
User process
U3
U2
U1
User Address Space
System process
S1
S2
S3
Management of names, processes, threads,
memory, and communication
K1
K2
Kernel Address Space
Micro-kernel
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How Chorus is Used in a Distributed
System-------------------------------------------
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• Three layer communication
• User interface to system
• System interface to kernel
• Kernel interface to micro-kernel
• Uses message passing between process and threads

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Features and Benefits of ChorusOS----------------
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• Memory Protection
• Hot Restart
• Dynamic Reconfiguration

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Features and Benefits of ChorusOS
Cont--------------------------------------------
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• Component-based architecture for
  super-configurability
• Mission-Critical Quality
• Exceptional scalability
• Transparent Distribution
• Code re-use
• Multiple OS personalities and APIs

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ChorusOS Application Overview--------------------
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• Wireless Networks
• Private and Public Switches (PBXs)
• Datacom Systems
• Internetworking Equipment
• Transmission Equipment
• Line Cards
• Cellular Networks
• Network Monitoring Equipment
• Satellite Transmission Systems

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Conclusion---------------------------------------
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• Micro-kernel based system used in distributed
  operating systems
• Provides binary compatibility with UNIX
• Consist of three layers
• Kernel contains micro-kernel
• Subsystems support for user programs
• User processes at top layer