What is RPC?

PRC is a remote procedure call, a protocol for requesting services from a remote computer program over a network without requiring knowledge of the underlying network technology.For example, two different services A and B are deployed on two different machines. What if service A wants to call a method in service B?It's certainly possible to use HTTP requests, but it may be more cumbersome.RPC came into existence to make calling remote methods as easy as calling local methods.

RPC principle

1. The service consumer (client) calls the service in the local call mode;

2. The client stub is responsible for assembling methods, parameters, etc. into a message body that can be transmitted over the network after receiving the call;

3. The client stub finds the service address and sends the message to the server;

4. The server stub decodes the message after receiving it;

5. The server stub calls the local service according to the decoding result;

6. The local service executes and returns the result to the server stub;

7. The server stub packs the returned result into a message and sends it to the consumer;

8. The client stub receives the message and decodes it;

9. The service consumer gets the final result.

Already have http protocol interface, why use RPC technology?

It is indeed a wise choice to use http when there are not many interfaces. For example, in a start-up company, we are not sure that the business can be carried out smoothly, and may face bankruptcy at any time, and there are not enough developers. At this time, it is simple and efficient to usetechnology, it is the wisest choice to make things first, and there is no need to go to the sky in one step.

In the case of less interaction between the system and the system, the advantages of using the http protocol are obvious: the development is simple, the testing is relatively straightforward, and the deployment is convenient, and the off-the-shelf http protocol is used for inter-system communication.It is also slowly expanding, and the benefits of the RPC framework are shown.

First of all, RPC supports long links, and communication does not have to repeat 3 handshakes every time like http, which reduces network overhead.

Secondly, the RPC framework generally has a registration center module with complete monitoring and management functions. Service registration and discovery, service offline, and service dynamic expansion are all easy to operate, and the efficiency of service-based governance is greatly improved.

RPC based on TCP protocol can customize protocol fields more flexibly. Compared with http, it can reduce the number of network transmission bytes, reduce network overhead (handshake) and improve performance.Achieving greater throughput and concurrency, but requires more attention to the underlying complex details, high requirements for developers, and increased development costs.