Utopia

Extension

Utopia |juːˈtəʊpɪə| noun

An imagined place or state of things in which everything is perfect. The word was first used in the book Utopia (1516) by Sir Thomas More.

ORIGIN based on Greek ou ‘not’ + topos ‘place.’

Introduction

Utopia is a modular library for the creation of networked music applications, and builds upon the work of the Republic Quark and other existing network systems in SuperCollider. It aims to be modular (features available largely 'à la carte'), secure (provides methods for authentication and encryption), and flexible (to the extent possible, it tries not to impose a particular design or architecture). It provides functionality for synchronisation, communication, code sharing, and data sharing.

Yes, that one...

Basic Building Blocks

The central class of Utopia is AddrBook. This is essentially a dictionary of Peer instances, which represent participants or nodes in a networked music system. AddrBook is not a singleton, and a given system could use multiple instances of it to represent different subgroups, etc. It provides methods for looking up and communicating with one or more members. Most objects in Utopia take an AddrBook as an argument, and respond to changes in it when appropriate. An AddrBook is generally used as a (possibly dynamic) collection of intended recipients for one or more types of communication, and where possible the use of broadcast messages is avoided to allow for precise managing of information flow.

Similarly, most classes allow you to specify an OSC path, which allows for things like multiple simultaneous chat networks (e.g. one for general chat, one for 'shouting'), or to further control membership in particular activities. In general objects signal change via Object's dependancy mechanism (see Object: Dependancy and http://en.wikipedia.org/wiki/Observer_pattern), which keeps the classes lightweight and loosely coupled, and makes the creation of custom GUIs etc., straightforward and quick.

Founding Your Utopia

From Garden Cities of Tomorrow (1902) by Ebenezer Howard

Utopia provides multiple ways of populating an AddrBook, depending on the desired system design:

De-centralised Discovery

The Hail class allows for Peers to automatically discover each other on a network.

Centralised Discovery

The Registrar/Registrant classes allow for centralised discovery. Peers register with a central node, which announces any changes in membership to all Peers. This could for instance be running on a machine not being used for sound production to allow for stability in the event of a Peer crashing.

Manual Discovery

One can also manually populate an AddrBook, which can be useful in cases when IP addresses and/or participants are fixed and known.

Citizen Communication

Utopia provides a variety of classes for communicating different sorts of information between Peers:

The Trådtelefon: A popular form of communication

Chatter

A class for text chat between Peers.

CodeRelay

Shares all code executed by a Peer with all other Peers in an AddrBook.

SynthDescRelay

Shares SynthDescs between Peers. (SynthDef sharing between multiple Servers can be accomplished using SynthDescLib.)

OSCDataSpace

A shared data space in the form of a dictionary of Open Sound Control data types (floats, ints, symbols).

OSCObjectSpace

A shared data space in the form of a dictionary of SC objects. Only archivable objects can be exchanged in this way, and there is no automatic syncing of changed state. Use with caution.

ConductorClock/FollowerClock

A centralised approach to a shared time base. Each ConductorClock can have multiple followers.

BeaconClock

An experimental attempt at a clock using Reference Broadcast Synchronisation. Decentralised and flexible, this approach should adapt to changing membership.

Guarding the walls

The discovery classes described above can take an authenticator object as an argument, to test whether joining Peers have permission to join an AddrBook. Currently Utopia supplies two types:

ChallengeAuthenticator

This uses a collection known to all participants as a challenge test. This could be something like the full text of War and Peace.

GroupPasswordAuthenticator

This uses a shared password to authenticate Peers attempting to join an AddrBook.

Some such palace or other...

GroupPasswordAuthenticator takes an encryptor as an argument, to prevent passwords being sent in plaintext. Encryptors can also be used by Utopia's chat, code-sharing, and data-sharing classes. There are currently two types:

NonEncryptor

This is a no-op class which is used in cases where no encryption is needed.

OpenSSLSymEncryptor

This uses OpenSSL's symmetric key abilities to encrypt data using a shared password. This requires that you have OpenSSL installed in your path. (See http://www.openssl.org/. OpenSSL comes standard on some operating systems.) The default cipher used is aes-128-cbc.

Expanding our borders

Utopia is currently an alpha release. It is an open source project and welcomes contibutions or suggestions. It is hosted at https://github.com/muellmusik/Utopia. Please file any requests or issues there.

Yet Another Utopia…