Push vs Pull Delivery Models in Distributed Systems

In the Push Model, the data producer or server initiates the transmission of data to downstream consumers immediately as new events are generated.

Core Push Protocols & Technologies:

• WebSockets (Full-Duplex TCP): Establishes a persistent, bidirectional connection over a single TCP socket. Enables sub-millisecond client-server messaging for live financial tickers, real-time collaborative editing (Google Docs), and multiplayer gaming.
• Server-Sent Events (SSE - HTTP/2): Unidirectional server-to-client streaming over standard HTTP. Lighter overhead than WebSockets for continuous text/event streams (e.g., LLM token streaming like ChatGPT, live sports score updates).
• Webhooks (HTTP POST Push): Third-party systems (e.g., Stripe, GitHub) push event payloads directly to a subscriber's public HTTP endpoint upon transaction completion.
• Push-Based Message Brokers (e.g., RabbitMQ, ActiveMQ): The broker pushes messages to connected worker threads over AMQP channels.

The Inherent Push Vulnerability: Producer-Consumer Speed Mismatch

When a high-throughput producer generates 100,000 events/sec while a downstream consumer can only process 10,000 events/sec, pushing unthrottled data causes consumer TCP socket buffers and JVM memory heaps to saturate, resulting in fatal Out-Of-Memory (OOM) crashes.