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architecturewalsecuritysession-management
Author: Platform TeamCreated: Oct 8, 2025Updated: Oct 8, 2025

WAL Full Transaction Flow

This diagram shows the complete lifecycle of a Write-Ahead Log transaction in Prism, including:

  • Client authentication and authorization
  • Write operations to WAL
  • Async database application
  • Session disconnection scenarios
  • Crash recovery

Sequence Diagram​

State Transitions​

Error Scenarios and Recovery​

Key Components​

Session Store Schema​

session:
  session_id: uuid
  client_id: string
  created_at: timestamp
  last_activity: timestamp
  ttl: integer (seconds)
  permissions: json
  metadata:
    ip_address: string
    user_agent: string
    connection_type: "mTLS" | "OAuth2"

WAL Message Schema​

wal_message:
  client_id: string
  namespace: string
  key: string
  operation: "insert" | "update" | "delete"
  data: bytes
  timestamp: int64
  checksum: string (SHA256)
  idempotency_key: uuid
  metadata:
    partition: int
    offset: int64

Checkpoint Schema​

checkpoint:
  consumer_id: string
  topic: string
  partition: int
  offset: int64
  timestamp: int64
  message_count: int64

Metrics​

# WAL lag (critical for monitoring)
prism_wal_lag_seconds{namespace="orders"} 0.15

# Unapplied entries
prism_wal_unapplied_entries{namespace="orders"} 10

# Session metrics
prism_active_sessions{proxy="proxy-1"} 1250
prism_session_expirations_total{reason="timeout"} 45
prism_session_expirations_total{reason="network_error"} 12

# Auth metrics
prism_auth_requests_total{result="success"} 50000
prism_auth_requests_total{result="forbidden"} 120

# Write latency (target: <2ms)
prism_wal_write_latency_seconds{quantile="0.99"} 0.0018

# DB apply latency
prism_db_apply_latency_seconds{quantile="0.99"} 0.015

References​

  • RFC-009: Distributed Reliability Data Patterns (Write-Ahead Log Pattern)
  • ADR-002: Client-Originated Configuration
  • ADR-035: Connection Pooling and Resource Management