Joystream Handbook
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Storage & Bandwidth
Storing and distributing static assets, such as videos, avatars, covers and attachments, to end users is a key service of the network, and a dedicated subset of actors in the DAO operate dedicated nod

Preamble

This subsystem is under active development, and this document attempts to both explain how the current production system (as of Giza) works, as well as give indications about what is expected to be added later before mainnet.

Introduction

The network has a variety of static data assets used in different context. In the content directory, for example, there are avatars and cover images used for channels, and also preview thumbnail images for videos, as well as the video media itself, which may exist in multiple different resolutions and encodings for the same content. In the membership system images are used for the avatar of a user, and there is also a generalized storage capability. There is also a generalised storage service for the benefit of the council and each individual working group, which are intended to be used for storing assets that are of use to actors occupying the given roles over time, or to the platform as a whole.

Storage Provider

Responsibilities

  • Run and maintain storage nodes that store very large quantities of static data, synchronize with other storage nodes, share data with distributors, and accepts inbound uploads from end users

Requirements

  • Experienced with how to setup and maintain high performance IT infrastructure
  • Access to highly performant and reliable IT infrastructure with high storage capacity
  • Hold sufficient amount of the native platform token to put at stake

Storage Provider Leader

Responsibilities

  • The Storage Lead is responsible for ensuring that Storage Providers are performing adequately. Each one must hold a complete and up-to-date copy of the content directory and ensure uptime in order to effectively serve content consumers.

Requirements

  • Experienced with how to setup and maintain high performance IT infrastructure
  • Ability to effectively manage and coordinate the actions of the Storage Providers
  • Hold sufficient amount of the native platform token to put at stake

Distributor

Responsibilities

  • Run and maintain distributor nodes that deliver large volumes of upstream data to a large number of simultaneous end users

Requirements

  • Experienced with how to setup and maintain high performance IT infrastructure
  • Access to highly performant and reliable IT infrastructure, with high storage capacity and a lot of upstream capacity
  • Located within certain bounds to designated geographic areas, in order to limit latency
  • Hold sufficient amount of the native platform token to put at stake

Distributor Lead

wip

Philosophy

Introduction

The handbook largely attempts to not motivate or frame how the system works, however, in the case of this subsystem it is sufficiently complex that it invariably generates a range of questions when confronted by newcomers, hence we attempt to address this more directly here.

Model

There is an obvious first-principles question of why the network has these capabilities built in, in the sense that it directly finances and coordinates the provisioning of these services internally through its own administrative bureaucracy, and using its own custom technology stack. Why can't the system just rely on AWS or some other similar offering?
The reason for this is that the network, as represented by its governance apparatus, cannot enter into traditional contractual arrangements directly with off-chain entities, like the operators of traditional cloud infrastructure. This is a consequence of both the contemporary business model constraints of such operators, and the limits of what most jurisdictions would consider valid counterparties in an enforceable contract. The only way to bridge this gap would be if the platform selected some on-chain intermediary who effectively custodied the business relationship with the platform on behalf of the network, however, this would be prohibitively risky should this actor become faulty or byzantine, as there would be no recourse.
A third alternative would have been to rely on other middleware blockchain systems which have been explicitly built for the purpose of providing these services, this includes offerings such as Arweave, Sia+SkyNet, Filecoin, Storj, Meson and similar systems. Each of these systems have their own idiosynchratic reason for why they may not be an ideal fit, or at least complete fit for the Joystream network. Some our pure storage solutions, other are pure CDN solutions, others are mixtures. Some focus on permanent storage, others on pay-as-you-go. They all provide different security models. However, uniformly, they all have the following problems
  • Immature: All of them are still very technically immature, both in tooling, documentation and community of developers using at any sort of serious scale. It is difficult to commit building anything beyond a prototype or proof-of-concept
  • Opaque: It is notoriously difficult to get a complete and accurate picture of what exact technical and economical guarantees the systems provide, and will provide, in the future. This is largely a consequence of the immaturity, but also that many question are likely unresolved, making it infeasible for the developers to commit to highly specific longer term roadmaps and timeline. The credibility of any actual public commitments are hard to evaluate.
  • Isolated: A critical requirement for any efficient platform is that it covers the costs and management on a variety of services on behalf of the users. This applies to the Joystream network as well, which means it must be able to deeply interoperate with any external middleware system, including control funds, issue service provisioning and manage ongoing expenses. This kind of complex interoperability between these systems is not feasible or simple at this time.
  • Temporary: When looking at the evolution of other large scale video provisioning platforms, such as YoutTube and Netflix, they invariably start out relying on external infrastructure, but over time they converge to relying on their own internally provisioned infrastructure. This is both because this infrastructure ends up becoming too strategically valuable to risk having to periodically bargain over it, and also because any discrepancy between the ideal cost structure and feature set required by client and their infrastructure ends up becoming prohibitibley costly when magnified by scale.
An important nuance to be aware of is that once the immaturity and opacity is no longer an issue, it would be feasible for the Joystream network to adopt, or augment, the technology - in terms of protocol and software - of the most appropriate third party alternative, while sidestepping the latter two problems of isolation and temporaryness. This is because there is a fundamental distinction between using the same technology, and using the same specific instantiated running external system for which that technology was initially built. So as an example, this would be the difference between using Filecoin the network and Lotus the full node software for that network.

Design

WIP.

Roles

There are two working groups involved in storage and bandwidth provisioning, one per subsystem. To learn more about working groups in general, please consult the https://github.com/Joystream/handbook/blob/master/system/storage/broken-reference/README.md document. The roles are here tasked with the following, beyond the normal working groups activities inherent to each:

Storage

  • Storage Lead: Briefly stated, the lead manages
    • what set of storage providers should store what data.
    • what storage workers can actively participate as storage providers.
    • how different categories of data should be automatically stored once uploaded.
    • the size sensitive component of the upload price.
    • the replication factor on future uploads.
    • the upload blacklist.
    • whether uploads are globally allowed or not at any given time.
  • Storage Worker/Provider:
    • Accepts and validates data uploaded from users for storage.
    • Replicates data initially stored with other storage providers.
    • Shares data with other storage providers and bandwidth providers.
    • Maintains public host resolution metadata.
    • Is incentivized by a mix of
      • user payment for uploads
      • probabilistic on-chain proof-of-storage challenges (not in Giza)
      • payment from peer providers & bandwidth providers when providing data (not in Giza)
      • slashing by discretion from group lead, with subsequent loss of reputational capital of membership in this role.
      • working group payments

Bandwidth

  • Bandwidth Lead:
    • what set of bandwidth providers should distribute what data.
    • what bandwidth providers can actively participate as providers.
    • how different categories of data should be automatically distributed.
    • policy metadata for groups
  • Bandwidth Worker/Provider:
    • Sends data to users on demand.
    • Replicates data from storage providers following local caching policy.
    • Maintains public host resolution metadata.
    • Is incentivized by a mix of
      • slashing by discretion from group lead, with subsequent loss of reputational capital of membership in this role.
      • payment from gateway providers (not in Giza)
      • working group payments

Concepts

Data Directory

An on-chain system which holds relevant state required to represent the data which is currently being stored, along with information about who owns it, how it is stored and how it is distributed. It also holds policy information about how to handle requests to introduce new data into the system. The node software that is operated by compliant storage and bandwidth providers uses this state as the ultimate source of truth for what they should be doing at any given time. There are a range of different extrinsic which facilitate updating the state of this system, such as uploading or deleting new data, or updating what a given provider should be doing.
For a detailed overview of how this system works, please review the https://github.com/Joystream/handbook/blob/master/system/storage/broken-reference/README.md document.

Nodes

There are two distinct node type, storage nodes and bandwidth nodes, each being a network peer that the corresponding provider type operates in order to provision their service to the network. There is a reference software implementation of each node, called Colossus and Argus, respectively, but in principle there could be alternative node implementations for the same underlying protocol described in document.
Storage nodes are primarily involved in
  • accepting uploads from users,
  • downloading data to be stored from other storage nodes,
  • uploading data to other storage nodes and bandwidth nodes that may require it,
  • dropping data which is deleted from the network,
and bandwidth nodes are primarily involved in
  • uploading data to users upon request,
  • downloading data from storage providers in accordance with local caching policy,
There is no direct protocol level enforcement of what service-level agreement each node should conform to, for example in terms of
  • storage capacity
  • up-time
  • up-speed
  • down-speed
  • connection capacity
  • latency w.r.t. a given location
but each provider type faces a range of different incentives that aim to encourage them to comply with agreed upon standards out-of-band, in the working group. There exists on-chain information for resolving the, or a, host corresponding to the node of a given provider, and the provider is free to update this mapping as needed. There is also no protocol level awareness of what kind of underlying infrastructure is powering the node, but for the purposes of this documentation one can imagine it to be a single host serving the reference API in a way described by the protocol, and with a single canonical internal state and view of the data directory and blockchain.

Service Game

WIP.

Architecture

The key architectural properties of the system is as follows
  • Distinct roles for storage and distributing data.
  • Storage with redundancy and only partial replication in nodes, but no erasure coding on individual data.
  • Bandwidth provisioning with flexible policy space, allowing for Content Delivery Network (CDN) like organization.
  • The blockchain holds index of data, including ownership and metadata, and critical information about what service provider is obliged to perform storage and distribution for a given piece of data.
  • When new data is added to the system, the blockchain has built in policies for deciding how storage and bandwidth services should be provisioned, but there is also room for manual intervention later to augment or change these initial determinations.
This can all be succinctly summarize in the following figure.
System Architecture

Scenarios

User Data Upload

WIP.

New Storage Provider

WIP.

New Bandwidth Provider

WIP.

User Data Download

WIP.

User Data Deletion

WIP.
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