RPC 1: how to develop RPC framework from scratch

Preface

RPC The frame is the knowledge point that the back-end siege lion can never get around , At present, some well-known in the industry are Dubbo、Spring Cloud etc. . Many people are stuck in the stage of only using , As a program ape , Have curiosity and study deeply , In order to effectively improve their competitiveness . Students on the next floor , Will go through the source code , See how the function is implemented , This is a good start . Look at the source code, it's easy to forget after a period of time , I think after reading the source code , It's better to develop one yourself , In this way, you will have a deeper understanding of the framework . In my submission ," Will use "、" Can read the source code "、" Will write it out " It's a completely different level .
This series " Of the wheel series RPC", Teach everyone how to build their own RPC frame .
The following is a simple version RPC Source code , welcome Star、Fork. Level co., LTD. , You have better ideas to put forward .
Github：https://github.com/chenchuxin/ccx-rpc
Gitee：https://gitee.com/imccx/ccx-rpc

RPC Structure of framework

One of the simplest RPC The framework is divided into three parts ： Registry Center 、 Server side 、 client . The following is the simplest structure flow chart .

Part of the ：

1. Registry Center ： Used to register and obtain services .
2. Server side ： Means the party providing the service , Also called service provider Provider
3. client ： Refers to the party calling the service , Also called service consumer Consumer

technological process ：

1. The server registers the service information in the registry , It usually contains the server address 、 Interface classes and methods
2. The client obtains the information of the corresponding service from the registry
3. According to the information of the service , Call the interface to the server through the network

RPC Frame design

Many details of the above process are not drawn , for example ：

1. In what form does the server register with the registry ？
2. How does the client call the service like an interface ？
3. What is the network protocol for invoking the service ？

A basic RPC frame , It needs to include the following parts ：

1. Registry Center ： The registration center is responsible for the registration and search of service information . When the server starts , Scan all services , Then register your service address and service name in the registry . Before the client invokes the service , Find the address of the service through the registry , You can call the service through the address of the service . Common registries are Zookeeper、Eureka etc. .
2. A dynamic proxy ： Client call interface , The framework needs to be able to call services remotely according to the interface , This step is not perceived by the user . thus , You need to use dynamic agents , User call interface , It's actually calling the dynamically generated proxy class . Common dynamic agents are ：JDK Proxy,CGLib,Javassist etc. .
3. Network transmission ：RPC A remote call is actually a network transfer , So network transmission is RPC An essential part of the framework . The network framework has Java NIO、Netty Frame, etc .
4. Custom protocol ： Network transmission needs to formulate a good protocol , A good protocol can improve the efficiency of transmission .
5. serialize ： Network transmission will certainly involve serialization , Common serialization methods are Json、Protostuff、Kyro etc. .
6. Load balancing ： When the number of requests is large , You need to increase the number of servers , Once added , It will involve the choice of services , This is load balancing . Common load balancing strategies are ： polling 、 Random 、 Weighted polling 、 Weighted random 、 Consistent hashes and so on .
7. Cluster fault tolerance ： When the request service is abnormal , Should we report the error directly ？ Try again ？ Or ask for other services ？ This is the cluster fault tolerance strategy .
8. ....

The above design , The code implementation will be introduced in detail in the next article .