rhizome-node/plans/beam-implementation.md

Rhizome on the BEAM: Implementation Guide

Note

: This document outlines a fresh implementation of Rhizome in Elixir, using the TypeScript implementation as a reference.

Table of Contents

• Motivation
• Architecture Overview
• Migration Strategy
• Key Components
• Data Synchronization Model
• Development Roadmap
• Performance Considerations

Motivation

Moving Rhizome to Elixir and the BEAM virtual machine provides several key advantages:

1. Distribution by Default

   • Built-in distribution primitives for node-to-node communication
   • Network partition tolerance out of the box
   • Location transparency for processes

2. Fault Tolerance

   • Let it crash philosophy with supervision trees
   • Self-healing systems through process isolation
   • Hot code reloading for zero-downtime updates

3. Concurrency Model

   • Lightweight processes for handling millions of concurrent connections
   • Efficient message passing between processes
   • Built-in backpressure handling

4. Ecosystem Benefits

   • Mature tooling for distributed systems
   • Strong pattern matching and immutability
   • Excellent support for building resilient systems

Architecture Overview

Current TypeScript Architecture

graph TD
    subgraph "TypeScript Implementation"
        A[HTTP API<br/><small>Express</small>]
        B[WebSocket<br/><small>Socket.IO</small>]
        C[Core Engine]
        D[Delta Store]
        E[View Layer]
        F[Persistence<br/><small>LevelDB</small>]
        G[Peer Network<br/><small>Libp2p</small>]
        
        A --> C
        B --> C
        C --> D
        C --> E
        D --> F
        C --> G
    end

Proposed Elixir Architecture

graph TD
    subgraph "Elixir Implementation"
        A[HTTP/WebSocket<br/><small>Phoenix</small>]
        B[Core OTP App]
        C[Delta Store]
        D[View Layer]
        E[Process Supervision]
        F[Distribution<br/><small>EPMD/GenRPC</small>]
        G[Persistence<br/><small>Mnesia/ETS</small>]
        
        A <--> B
        B <--> C
        B <--> D
        B <--> E
        B <--> F
        C <--> G
    end

Implementation Roadmap

1. Core Engine

• Delta Processing

  • Define core Delta types and operations
  • Implement DeltaBuilder
  • Design storage layer (Mnesia/ETS)

• View System

  • Implement Lossy/Lossless views
  • Create resolver framework
  • Add caching layer

2. Distribution

• Node Communication

  • Node discovery and membership
  • Delta synchronization protocol
  • Conflict resolution strategies

• Plugin System

  • Plugin behavior and lifecycle
  • Dependency management
  • Hot code reloading

3. API & Tooling

• HTTP/WebSocket API

  • RESTful endpoints
  • Real-time updates
  • Authentication/authorization

• Developer Experience

  • TypeScript type generation
  • CLI tools
  • Monitoring and metrics

Key Components

1. Delta Processing

This implementation will follow similar patterns to the TypeScript version but leverage Elixir's strengths:

defmodule Rhizome.Delta do
  @type t :: %__MODULE__{
    id: String.t(),
    creator: String.t(),
    timestamp: integer(),
    operations: [operation()],
    transaction_id: String.t() | nil,
    negate: boolean()
  }
  
  defstruct [:id, :creator, :timestamp, :operations, :transaction_id, negate: false]
  
  def new(creator, host) do
    %__MODULE__{
      id: generate_id(),
      creator: creator,
      timestamp: System.system_time(:millisecond),
      operations: []
    }
  end
  
  def add_operation(delta, operation) do
    %{delta | operations: [operation | delta.operations]}
  end
end

2. View System

defmodule Rhizome.View.Lossy do
  @behaviour Rhizome.View.Behaviour
  
  @impl true
  def init(initial_state) do
    %{state: initial_state, cache: %{}}
  end
  
  @impl true
  def reduce(%{state: state} = view, delta) do
    new_state = apply_delta(state, delta)
    %{view | state: new_state}
  end
  
  @impl true
  def resolve(%{state: state}), do: state
  
  defp apply_delta(state, %Delta{operations: ops}) do
    Enum.reduce(ops, state, &apply_operation/2)
  end
end

3. Plugin System

defmodule Rhizome.Plugin do
  @callback init(args :: term) :: {:ok, state :: term} | {:error, reason :: term}
  @callback handle_delta(delta :: Delta.t(), state :: term) :: {:ok, new_state :: term} | {:error, term}
  @callback handle_call(request :: term, from :: {pid, reference}, state :: term) ::
    {:reply, reply, new_state} |
    {:reply, reply, new_state, timeout | :hibernate} |
    {:noreply, new_state} |
    {:noreply, new_state, timeout | :hibernate} |
    {:stop, reason, reply, new_state} |
    {:stop, reason, new_state} when reply: term, new_state: term, reason: term
  
  defmacro __using__(_opts) do
    quote do
      @behaviour Rhizome.Plugin
      use GenServer
      
      # Default implementations
      @impl true
      def init(_args), do: {:ok, %{}}
      
      @impl true
      def handle_call(_request, _from, state), do: {:reply, :ok, state}
      
      def start_link(args) do
        GenServer.start_link(__MODULE__, args, name: __MODULE__)
      end
    end
  end
end

Data Synchronization Model

1. Delta Propagation

sequenceDiagram
    participant C1 as Client 1
    participant N1 as Node 1
    participant N2 as Node 2
    participant N3 as Node 3
    
    C1->>N1: Submit Delta
    N1->>N1: Apply Delta Locally
    N1->>N2: Gossip Delta
    N1->>N3: Gossip Delta
    N2->>N2: Apply Delta
    N3->>N3: Apply Delta
    N2->>N1: Acknowledge
    N3->>N1: Acknowledge

2. Conflict Resolution

1. Last Write Wins (Default)
2. Custom Resolvers
3. CRDT-based for special cases

Development Milestones

1. Core Delta Engine

• Define delta types and operations
• Implement DeltaBuilder
• Basic storage with Mnesia/ETS
• View system with Lossy/Lossless support

2. Distributed Foundation

• Node discovery and membership
• Delta synchronization protocol
• Conflict resolution strategies
• Plugin system

3. Production Features

• HTTP/WebSocket API
• Authentication & authorization
• Monitoring and metrics
• Developer tooling

Performance Characteristics

Key Advantages

1. Concurrency

   • Handle 100K+ concurrent connections per node
   • Sub-millisecond delta processing
   • Linear scaling with cores

2. Memory Usage

   • Shared binary heap for deltas
   • Efficient garbage collection
   • Process isolation for fault tolerance

3. Network Efficiency

   • Delta compression
   • Batched updates
   • Smart backpressure handling

Getting Started

Prerequisites

• Elixir 1.14+
• Erlang/OTP 25+
• Node.js (for assets)

Running Locally

# Clone the repository
git clone https://github.com/your-org/rhizome-beam.git
cd rhizome-beam

# Install dependencies
mix deps.get
cd assets && npm install && cd ..

# Start the application
iex -S mix phx.server

Contributing

1. Fork the repository
2. Create a feature branch
3. Submit a pull request

License

[Your License Here]

Acknowledgments

• The Elixir and Erlang communities
• The original TypeScript implementation for inspiration
• Research in distributed systems and CRDTs