Understanding the Differences Between RPC and HTTP Services

Many developers are unclear about the difference between RPC (Remote Procedure Call) and HTTP calls; this article clarifies that RPC is built on TCP/IP while HTTP services operate at the application layer using the HTTP protocol.

To understand the contrast, the OSI seven‑layer model is introduced, emphasizing that the application layer (where HTTP lives) and the transport layer (where TCP resides) are the most relevant for comparing RPC and HTTP.

RPC services consist of four core components: a client, a server, a client stub that packages requests and sends them over the network, and a server stub that unpacks the request and invokes local methods.

The client initiates calls, the server provides the actual service, the client stub holds server address information and handles request serialization, and the server stub performs deserialization and method execution.

Calls can be synchronous—where the client waits for a result—or asynchronous—where the client proceeds without waiting and may receive a callback; this mirrors Java’s Callable and Runnable interfaces, with Future used to retrieve asynchronous results.

Three widely used open‑source RPC frameworks are highlighted: gRPC , a Google project based on HTTP/2.0 and Netty; Thrift , a Facebook cross‑language framework with an IDL code generator; and Dubbo , an Alibaba framework known for pluggable protocols and serialization.

HTTP services are typically RESTful APIs that expose endpoints such as POST http://www.httpexample.com/restful/buyer/info/shar , returning JSON or XML; they are simple, direct, and fast to develop, especially for small‑scale integrations.

For large enterprises with many subsystems, RPC offers advantages like persistent connections (reducing handshake overhead) and built‑in service registries for monitoring and dynamic scaling, whereas HTTP is better suited for lightweight, quickly iterated services.

In conclusion, the choice between RPC and HTTP should be based on a thorough evaluation of project requirements rather than simply following market trends.