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Inferno

Distributed Programming With Inferno®

Larry RauMember of Technical Staff

Inferno Network Software SolutionsLucent Technologies, Inc

larryr@lucent.com

http://www.lucent.com/inferno

aVsonline.blogspot.comaVs997 techfamily

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Inferno®

The Inferno OS

• Lightweight OS for networked devices– portable -- StrongARM, PowerPC, x86, MIPS,

SPARC.– Integrated DIS™ VM -- supports portable

machine independent code modules.– Provides “distributed computing” capability

through Namespace and Styx™ Technologies – Authentication and Encryption between

nodes.

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Inferno®

Distributed Computing Capabilities

• The Inferno OS is built around a unique method of distributed computing– All resources represented as files– A dynamically adjustable namespace– The Styx™ file access protocol

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Inferno®

Inferno File Systems

• Inferno views virtually everything as a file system– network interface: /dev/tcp, /dev/udp,...– process information: /prog– window system: /dev/draw– information: /dev/user, /dev/time,

/dev/sysname, /dev/random,….

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Inferno®

Example: TCP Interface

Access a TCP/IP network by manipulating the following files:puck$ ls /net/tcp/0

/net/tcp/0/ctl

/net/tcp/0/data

/net/tcp/0/listen

/net/tcp/0/local

/net/tcp/0/remote

/net/tcp/0/status

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Inferno®

Example: /dev/draw

Access to the Inferno windowing system is via another file system:puck$ ls /dev/draw/2

/dev/draw/2/ctl

/dev/draw/2/data

/dev/draw/2/refresh

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Inferno®

Other existing file systems

• telfs: interface to telephony device

• Mfs: message store file system

• asr: interface to speech recognition

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Inferno®

Why file systems?

• Simple concept– familiar access methods: open, read, write,

etc.

• language neutral access

• Easy to distribute

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Inferno®

The Inferno Namespace

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

•Every process accesses its resources via its own namespace– can inherit from parent– share with other processes

•Local and remote resources are bound into the namespace.

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Inferno®

Primary Namespace Operations

• BIND

• MOUNT

• EXPORT

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Inferno®

The BIND Namespace Operation

• Attaches local resources to the namespace

• Moves a resource within the namespace

• Can hide resources by binding over

• Binding a directory can result in a Union Directory

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Inferno®

Union Directories

• A directory whose contents are a combination of the source and destination

• Directories can be stacked where the contents of one hide the contents of others.

• When binding you have the option of adding before or after the current contents

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Inferno®

Union Directories

tmp

/

YF1 F2 F3

AF1 A1 A2

...

......

ZF2 A1 B1

......

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Inferno®

AF1 A1 A2

A YF1 F2 F3

Union Directories

/

AF1 A1 A2

...

ZF2 A1 B1

......

bind -b /tmp/Y /A

bind -a /tmp/Z /A

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Inferno®

The MOUNT Namespace Operation

• Attaches a remote file system to the namespace

• Equivalent to a remote attach to obtain the remote file system’s root followed by a BIND operation

• Mount initiates a Styx connection over an established network connection

• Net connection can be authenticated

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Inferno®

Mounting A Remote Node

• Establish a network connection: TCP, Serial, ATM, etc.

Node2Node1

• [optional] Mutually authenticate the connection and establish session keys for encryption of all communication

• Establish a Styx session: this obtains the root of the remote file system

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Inferno®

The EXPORT Namespace Operation

• Present the current namespace to remote clients

• Listens on a network connection for a Styx session request

• Accepts the mount by providing access to the root of the namespace

• Continually responds to client file requests via the Styx protocol

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Inferno®

Exporting a Namespace

• Obtain a network connection: TCP Listen, etc

Node2Node1

• [optional] Perform mutual authentication and encryption key setup

• Wait for Styx session request

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Inferno®

Mini-Summary

• Represent all local resources as file systems

• Namespace provides a single, dynamically configured, hierarchical view of all resources (I.e. file systems)

• Remote resources attached to the namespace

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Inferno®

Writing Applications

• Applications access resources by accessing files within the namespace

• Use familiar file access functions

• Access is independent of how the files got in the namespace -- local,remote, who cares!

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Inferno®

Writing File Systems

• Inferno drivers: C modules linked with the kernel

• Limbo programs using the file2chan() system call– makes use of srv device (I.e. file system)

• Limbo written Synthetic File Systems• InfernoSpaces

– Java class library– C library

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Inferno®

Application Advantages

• Applications can assume location of resources: open(“/x/y”,…)

• Resources can be configured prior to running the applications -- (I.e. an administrative chore)

• No explicit networking code required

• Allows for network independent distributed computing

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Inferno®

The Styx™ Protocol

• A simple file access protocol• Message passing: transmit-reply (a Styx

Transaction)• Synchronous• 13 message pairs + 1 error reply• Assumes a reliable transport• Allows overlapped transactions• Mostly fixed length messages

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Inferno®

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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Inferno®

Styx Transactions

• NOP• FLUSH• CLONE• WALK• OPEN• CREATE• READ

• WRITE• CLUNK• REMOVE• STAT• WSTAT• ATTACH

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Inferno®

Summary

Everything is a file +

A method to organize files +

A remote file access protocol =A Distributed Programming Model

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Inferno®

How is it being used

• Telephony– Call setup– Device control

• Text to Speech

• Network Gateways

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Inferno®

Questions

???