HTTP vs RPC in Spring Cloud: A Technical Comparison and Guidance

Author: 简简单单神经蛙 Source: blog.csdn.net/m0_61878423/article/details/124607067

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Regarding Spring Cloud remote calls, it adopts HTTP instead of RPC.

1. Spring Cloud enables web services by embedding a Tomcat container. Using HTTP requests with JSON payloads allows flexible business data handling, cross‑platform communication, and a single server can serve mobile H5, apps, and mini‑programs.

2. RPC is based on TCP, requiring a three‑way handshake and a stable connection. It transmits binary data, relying on serialization/deserialization rules, which makes it less flexible for frequently changing data; it is typically used for socket connections or fixed‑format data.

Establishing a socket connection needs a pair of sockets: a client socket (ClientSocket) and a server socket (ServerSocket). The connection process includes server listening, client request, and connection confirmation.

Simple HTTP Request Handling

In a web application, the browser requests a URL, the server returns the generated HTML page via HTTP. Below is an example of implementing a simple HTTP server in Java.

RPC

RPC (Remote Procedure Call) is an inter‑process communication method that allows a program to invoke a procedure on a remote machine as if it were local, without the programmer needing to handle the network details.

For example, if two servers A and B each host an application, and A wants to call a method provided by B, the call must go over the network because they are not in the same JVM; this network call is called RPC.

RPC has two core modules: communication and serialization.

Note: Regardless of data type, it must be serialized into a binary stream for network transmission; the sender serializes the object, and the receiver deserializes it back.

Restful (HTTP)

Restful refers to a set of architectural constraints and principles. If an architecture conforms to these constraints, it is called Restful. The idea is to leverage existing Web features and standards for better usage.

Although Restful is heavily influenced by Web technologies, theoretically it is not bound to HTTP; however, HTTP is the most common implementation.

Differences Between RPC and HTTP

Both have request‑response patterns.

Differences:

RPC aims to make remote calls look like local calls, encapsulating the call process at the API level.

HTTP does not impose such requirements; developers must implement request and response details themselves.

Advantages

RPC is more transparent and convenient for users.

HTTP is more flexible, language‑agnostic, and cross‑platform.

Disadvantages

RPC requires API‑level encapsulation, limiting language environments.

Choice Considerations

Speed: RPC is generally faster because both use TCP, but HTTP messages are bulkier (can be compressed with gzip).

Complexity: RPC implementation is more complex; HTTP is relatively simple.

Flexibility: HTTP is more flexible, does not bind to implementation details, and works across platforms and languages.

Future Development Direction

Microservices emphasize independence, autonomy, and flexibility. Because RPC has many constraints, most microservice frameworks adopt HTTP‑based Restful services.

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