Enterprise Marketing Webhook Dispatch Engine Technical Specification

Role: Principal Distributed Systems Architect with 15+ years of experience designing fault-tolerant event-driven architectures.

Context

• Target Throughput: {{target_throughput_qps}}
• Tenant Tiering & Rate Limits: {{tenant_tier_limits}}
• Event Schema Structure: {{event_payload_schema}}
• Retry & Backoff Configuration: {{retry_backoff_strategy}}
• Signature & Auth Verification: {{auth_verification_method}}

Task

Produce an exhaustive backend technical specification for a multi-tenant webhook dispatch engine that guarantees at-least-once delivery of marketing automation and CRM telemetry events while isolating noisy tenants.

Method

1. Analyze {{target_throughput_qps}} and {{tenant_tier_limits}} to define the queue topology, partitioning keys, and worker pool sizing.
2. Design the payload serialization and signing flow using {{auth_verification_method}} to ensure tamper-proof delivery to customer endpoints.
3. Model the egress delivery lifecycle, detailing connection pooling, DNS caching, dynamic timeouts, and circuit breaker states.
4. Formalize the tiered retry mechanism based on {{retry_backoff_strategy}}, distinguishing between transient HTTP 429/5xx responses and fatal 4xx errors.
5. Specify the Dead Letter Queue (DLQ) triage, customer notification triggers, and manual replay API endpoints.
6. Detail observability metrics (p95/p99 dispatch latency, success rates by tenant tier) and structured audit logging for egress compliance.
7. Define the data retention policy for delivery attempts, idempotency keys, and raw payload archival.

Constraints

• MUST define explicit HTTP connection timeout, TLS handshake timeout, and socket read limits to prevent slowloris worker exhaustion.
• MUST include a tenant fair-share algorithm to prevent high-volume marketing campaigns from starving lower-tier tenants.
• MUST NOT allow unencrypted transmission of webhooks under any circumstance.
• Provide concrete JSON schema definitions for dispatch metadata and DLQ envelope models.

Output format

• Section 1: System Architecture & Ingestion Flow (200-300 words)
• Section 2: Queue Partitioning & Fair-Queueing Strategy (250-350 words)
• Section 3: Delivery Lifecycle, Circuit Breaking & Retries (300-400 words)
• Section 4: Security, Signing & Payload Schemas (JSON schemas included)
• Section 5: Operational Runbooks, DLQ Replay & Monitoring Matrix

Self-review

• Does the queue design prevent single-tenant traffic spikes from impacting cluster-wide SLA?
• Are all HTTP retry classes (transient vs terminal) explicitly mapped in the backoff logic?
• Does the signing algorithm prevent replay attacks using timestamps and cryptographic nonces?