Choosing Between RPC and HTTP: When Speed, Flexibility, and Governance Matter

Overview of RPC and HTTP Interfaces

Both RPC (Remote Procedure Call) and HTTP interfaces are widely used in production; RPC is a method that typically runs over TCP (or optionally HTTP), while HTTP is a protocol that operates on top of TCP. Because HTTP itself relies on TCP, RPC services are generally lighter weight and more efficient.

RPC Service Architecture

An RPC service consists of four core components: Client, Server, Client Stub, and Server Stub.

Client : the caller of the service.

Server : the provider of the service.

Client Stub : stores the server address, packages request parameters into a network message, and sends it to the server.

Server Stub : receives the client’s message, unpacks parameters, processes the request, and returns the result.

RPC’s efficiency allows client and server teams to develop independently once the interface contract is defined, enabling decoupling and reuse across projects. RPC calls can be synchronous (client waits for a response) or asynchronous (client proceeds without waiting, using callbacks or one‑way calls).

Popular RPC Frameworks

gRPC : Google’s open‑source project built on HTTP/2, supporting many programming languages and using Netty under the hood.

Thrift : Facebook’s cross‑language service framework with an IDL code generator that abstracts the underlying RPC communication.

Dubbo : Alibaba’s widely adopted open‑source RPC framework, notable for pluggable protocols and serialization mechanisms.

HTTP Service Development

HTTP services are accessed via URLs and are typically implemented as RESTful APIs. They are simple, direct, and easy to develop, especially when the number of interfaces is small and inter‑system interaction is limited.

RESTful services follow a Resource‑Oriented Architecture (ROA) and use standard HTTP verbs: GET /user – retrieve user data. POST /user – create a new user. PUT /user – update user information. DELETE /user – delete a user.

Key Differences Between RPC and HTTP

Transport Protocol

RPC: can run over TCP or HTTP.

HTTP: strictly uses the HTTP protocol.

Transmission Efficiency

RPC: custom TCP or HTTP/2 reduces message size and improves efficiency.

HTTP: HTTP/1.1 adds overhead; HTTP/2 can be more efficient but still often carries extra metadata.

Performance Overhead

RPC: binary protocols like Thrift provide low‑latency serialization.

HTTP: typically JSON‑based, which is larger and slower to serialize.

Load Balancing

RPC frameworks usually include built‑in load‑balancing strategies.

HTTP services often require external load balancers such as Nginx or HAProxy.

Service Governance

RPC: can automatically notify downstream services of changes, minimizing impact on upstream callers.

HTTP: changes usually require manual updates to proxy configurations.

RPC is ideal for internal service calls where low latency and efficient governance are critical, while HTTP/RESTful APIs excel in heterogeneous, external environments such as browsers, mobile apps, and third‑party integrations.

Choosing the Right Approach

If maximum performance and a unified technology stack are required, RPC is often the better choice.

If flexibility, cross‑language compatibility, and ease of integration are priorities, HTTP/RESTful services are preferable.

Modern microservice architectures tend to favor HTTP/RESTful APIs for external exposure, while internal communication may still rely on high‑performance RPC frameworks.