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Overview :IntroductionDesign principlesInferno InterfacesApplication LayerKernel LayerHardware LayerInferno ResourcesPros & ConsQuestions

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Introduction:Developed in Lucent technologies by Dennis Ritchie. but is now

developed and maintained by Vita Nuova Holdings as free software.

Replaces a plethora of protocols in a network by a simple unifying file service protocol (styx).

Applications compute their own name spaces and consider all resources as file systems.

Inferno was based on the experience gained with Plan 9 os from Bell Labs.

The name of the operating system and many of its associated programs, as well as that of the current company, were inspired by Dante Alighieri's Divine Comedy.

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Inferno's definitive strength lies in its portability and versatility across several dimensions:

Portability across processors

Portability across environments

Minimal hardware requirements

Portable applications

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Design Principles:-

Inferno was first made in 1995 by members of Bell Labs' Computer .It is a distributed operating system based on 3 basic principles drawn from Plan 9.

Resources as files:- all resources are represented as files within a hierarchical file system .The advantages of using file systems are:-

File systems have simple and well understood interfaces across a wide variety of operating systems.

Naming conventions for files are well known, uniform and easily understood

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Reliance on file systems reduces the amount of interface code and keeps the Inferno system small, reliable and highly portable .

Access rights and permissions to files are simple, yet can be used to ensure multiple levels of security

NAMESPACE:-the application view of the network is a single, coherent namespace

that appears as a hierarchical file system but may represent physically separated (locally or remotely) resources.

The Inferno Namespace is a hierarchical collection of files (i.e. resources).

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Every process accesses its resources via its own namespacecan inherit from parentshare with other processes

Local and remote resources are bound into the namespace

Standard communication protocol: a standard protocol, called Styx,is used to access all resources, both local and remote.

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Styx Message Structure:-

fid Contents

Message specific data

Unsigned integer that represents “current” file

Unique identifier used to track commands

Indicates message type: initial transmission (T-message) or reply message (R-message)

tagtype

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History:-DATE RELEASE COMMENT

1996 Inferno Beta Released by Bell Labs

1998 Inferno Release 1.0Winter 1997 Bell Labs Technical Journal Article

2000 Inferno 2nd Edition Released by Lucent's Inferno Business Unit

2003 Inferno 3rd Edition Released by Vitanuova

2005 Inferno 4th EditionOpen Source release; changes to many interfaces (incompatible with earlier editions); includes support for 9P2000.

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Inferno Interfaces:-

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Inferno has mainly three layers.

(i) Application layer

(ii) Kernel layer

(iii)Hardware layer

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Application Layer:-

Limbo is fully type checked at compile and run time.

No memory protection H/W is there.

All LIMBO data and program objects are subject to a garbage collector built deeply into LIMBO run time system.

All System data objects are kept track of and freed as soon as they become idle.

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DisVirtualmachine: - Limbo programs are compiled into byte-codes representing instructions for a virtual machine called Dis.

Dis has 3 address machine , supplemented with few specialized operations for handling arrays and strings.

The byte codes are expanded into a format more efficient for execution.

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Kernel Layer:-Namespace :

Memory management

Process management

Security in Inferno

Security mechanisms

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Hardware Layer:- Device drivers:- A device driver simplifies programming by acting as a

translator between a device and the applications or operating systems that use it

In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device.

A driver typically communicates with the device through the computer bus or communications subsystem to which the hardware is connected.

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Host os:- Inferno can run in different host operating system

Host systems Windows NT/2000/XPLinuxMacOSPlan9osSolaris

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Inferno Resources:-

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External Environment of Inferno Applications :-

The purpose of most Inferno applns is to present information n/media to user.

Regardless of whether resources are local/global, a communication protocol called styx is used.

The glue that connects diff parts of the resource name space together is the styx protocol.

Inferno kernel implements a mount driver which transforms file operations to RPC’s for transport over the network.

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Internal Environment of Inferno Applications:-LIMBO programs are built of modules, which are self

contained units .

Modules are accessed dynamically by executing a load statement.

Limbo is fully type checked at compile and run time.

No memory protection H/W is there.

All System data objects are kept track of and freed as soon as they become idle.

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Advantages:-

Cross platform integration

Transparent resource access

Secure communication

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Future scope:-

TelephonyCall setupDevice control

Text to Speech

Network Gateways

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Conlcusion:-“ Inferno does have a full-blown operating system and a virtual machine

and a protocol stack, and in a lot of respects is something Java would like to be when it grows up. “ - Peter Bernstein,

Inferno is a unique network operating system that adapts to whatever you plug into it -- from a high-end workstation to an inexpensive hand-held device," noted Dennis Ritchie,

One of the most significant differences between Inferno and other operating systems such as JavaOS is the way in which Inferno presents network resources to an application.

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References:-Bell Labs Technical Journal.Plugins, Vita Nuova.http://code.google.com/p/inferno-ds.www.vitanuova.com

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QUESTIONS