Backend Development 12 min read

Why RPC Is Essential for Building Scalable IM Clusters: A Beginner’s Guide

This article explains the fundamentals of Remote Procedure Call (RPC), why it is crucial for developing production‑grade instant‑messaging clusters, how it differs from plain HTTP, the typical RPC call flow, common frameworks such as gRPC, Thrift and Dubbo, and practical considerations for high‑throughput distributed systems.

Architecture & Thinking
Architecture & Thinking
Architecture & Thinking
Why RPC Is Essential for Building Scalable IM Clusters: A Beginner’s Guide

1. Introduction

Developers often wonder why they need an IM cluster when a single machine can handle modest traffic; however, when user numbers reach millions, a scalable cluster becomes necessary. Building a production‑grade IM cluster is challenging because instant messaging relies on long‑living connections, unlike traditional short‑lived HTTP requests.

We illustrate the message flow with two users (A and B) connected to different IM instances. The message must travel from instance 1 to instance 2 before reaching the recipient.

1) User A sends a message to IM instance 1.

2) Instance 1 forwards the message to instance 2.

3) Instance 2 delivers the message to user B.

The critical step is step 2, which is handled by RPC technology.

Distributed IM architecture with RPC
Distributed IM architecture with RPC
distributed systemsmicroservicesbackend-developmentRPCIM
Architecture & Thinking
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Architecture & Thinking

🍭 Frontline tech director and chief architect at top-tier companies 🥝 Years of deep experience in internet, e‑commerce, social, and finance sectors 🌾 Committed to publishing high‑quality articles covering core technologies of leading internet firms, application architecture, and AI breakthroughs.

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