Why not use - HTTP - instead of - RPC for calls between services?, Tencent background development

Here's another online sequence diagram ：

RPC What problems have been solved ？

From above RPC In the content of the introduction , A nutshell RPC Mainly solved ： Make calls between different services in a distributed or microservice system as simple as local calls .

common RPC Framework summary ?

• RMI（JDK Bring their own ）：?JDK Self contained RPC, There are many limitations , It is not recommended to use .

• Dubbo:?Dubbo yes Alibaba open source a high-performance excellent service framework , Enables applications to pass high-performance RPC Realize the output and input functions of services , You can talk to Spring Seamless integration of framework . at present Dubbo Has become a Spring Cloud Alibaba The official component in .

• gRPC?：gRPC It's a modern open source high performance that can run in any environment RPC frame . It can effectively connect services within and across data centers through pluggable support , To achieve load balancing , track , Health checks and authentication . It also applies to the last mile of Distributed Computing , To put the equipment , Mobile applications and browsers connect to back-end services .

• Hessian：?Hessian It's a lightweight remotingonhttp Tools , Using a simple method provides RMI The function of . comparison WebService,Hessian It's simpler 、 quick . It's binary RPC agreement , Because it uses binary protocol , So it's good for sending binary data .

• Thrift：?Apache Thrift yes Facebook Open source, cross language RPC Communication framework , It has been donated to Apache Foundation management , Because of its cross language features and excellent performance , It's used by many Internet companies , Companies with capabilities can even be based on thrift Develop a distributed service framework , Add services such as registration 、 Service discovery and other functions .

both HTTP , Why RPC Make service calls ?

###RPC It's just a design

RPC It's just a concept 、 A design , Just to solve it ? Call between different services , It usually contains ? Transfer protocol ? and ? Serialization protocol ? these two items. .

Realization RPC The transport protocol can be built directly on TCP above , It can also be built on HTTP The agreement above . Most of the RPC Frameworks are used TCP Connect （gRPC Used HTTP2）.

HTTP and TCP

Maybe now many friends who are not familiar with computer network have been confused , To really understand , Also need to briefly review the basic knowledge of computer network ：

We usually talk about the architecture of five layer protocol of computer network ： application layer 、 Transport layer 、 The network layer 、 Data link layer 、 The physical layer .

** application layer (application-layer） The task is to complete a specific network application through the interaction between application processes .**HTTP Belongs to the application layer protocol , It will be based on TCP/IP Communication protocol to transmit data （HTML file , Picture file , Query results, etc ）.HTTP The protocol works on the client side - The server architecture is top . Browser as HTTP Client pass URL towards HTTP The server is WEB The server sends all requests .Web After the server receives the request , Send response information to client .HTTP The agreement is based on TCP The agreement above .

Transport layer (transport layer) The main task is to provide general data transmission services for the communication between two host processes .TCP It's the transport layer protocol , It mainly solves how to transmit data in the network . Compared with UDP,TCP? What is offered is Connection oriented Of , reliable Data transmission service .

The key is HTTP The use of TCP agreement , And our custom TCP The difference of protocol in message .

http1.1 Agreed TCP The message contains too much information that may be useless during transmission ：

HTTP/1.0 200 OK 
Content-Type: text/plain
Content-Length: 137582
Expires: Thu, 05 Dec 1997 16:00:00 GMT
Last-Modified: Wed, 5 August 1996 15:55:28 GMT
Server: Apache 0.84

<html>
  <body>Hello World</body>
</html>



###  Last 

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