Inferno

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Inferno

• Distributed Programming With InfernoLarry
  RauMember of Technical Staff
• Inferno Network Software Solutions
• Lucent Technologies, Inclarryr_at_lucent.com
• http//www.lucent.com/inferno

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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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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 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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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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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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Other existing file systems

• telfs interface to telephony device
• Mfs message store file system
• asr interface to speech recognition

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Why file systems?

• Simple concept
• familiar access methods open, read, write, etc.
• language neutral access
• Easy to distribute

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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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Primary Namespace Operations

• BIND
• MOUNT
• EXPORT

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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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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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Union Directories
...
...
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Union Directories
bind -b /tmp/Y /A
bind -a /tmp/Z /A
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The MOUNT Namespace Operation

• Attaches a remote file system to the namespace
• Equivalent to a remote attach to obtain the
  remote file systems 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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Mounting A Remote Node

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

• 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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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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Exporting a Namespace

• Obtain a network connection TCP Listen, etc

• optional Perform mutual authentication and
  encryption key setup

• Wait for Styx session request

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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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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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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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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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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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Styx Message Structure
Indicates message type initial transmission
(T-message) or reply message (R-message)
Unique identifier used to track commands
Unsigned integer that represents current file
Message specific data
fid
Contents
tag
type
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Styx Transactions

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

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

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Summary

• Everything is a file
• A method to organize files
• A remote file access protocol
• A Distributed Programming Model

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How is it being used

• Telephony
• Call setup
• Device control
• Text to Speech
• Network Gateways

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Questions

• ???