RPC Technology

RPC What is it?

remote procedure call: Remote procedure call , Process refers to business processing 、 Calculation task , More straightforward understanding of , It's the program .( Call a remote procedure like a local method .)RPC use Client-Server structure , adopt request-response Message mode implementation .

Related issues

1. RPC and RMI What's the difference?

RMI(remote method invocation) The remote method call is oop In the field RPC A specific matter of .

2. Familiar to us webservice、restfull The interface call is RPC Do you ？

   All are RPC, Only the message organization and message protocol are different .

3. What is the role of remote procedure calls compared to local ?

   Speed is slow

   Weak reliability

RPC The process of

1. During client processing call Client stub() Proxy object ( It's like calling a local method ), Pass parameters ;
2. Client stub The parameter marshalling For message , Then send the message to the server through the system call ;
3. The client local operating system sends messages from the client machine send out To the server machine ;
4. The data that the server operating system will receive Pass on to Server stub;
5. Server stub Disaggregation Messages are parameters ;
6. Server stub Call again The process on the server side , The process execution results are given to the client in the same steps in the opposite direction .

RPC What is the protocol

RPC Parameters need to be grouped into messages to be sent during the call , The receiver needs to ungroup the message as a parameter , The process processing results also need to be grouped 、 Disaggregation .

** The message protocol is composed of which parts of the message and the formation of the message representation .**RPC The message protocol used in the call is called RPC agreement .

RPC The agreement provides for the request 、 The format of the response message ,

stay TCP( Network transmission control protocol ) You can choose or customize the message protocol to complete RPC Message interaction , We can choose a general standard protocol ( Such as ：http、https), You can also define your own message protocol according to your own needs !

common RPC agreement

XML-RPC is an RPC protocol that uses XML to encode its calls and Http as a transport mechanism.

JSON-RPC is an RPC protocol that uses JSON-encoded messages

SOAP is successor of XML-RPC and also uses XML to encode its HTTP-based call.

RPC What is the frame

Encapsulate the parameter group 、 Message ungrouping 、 The underlying network communication RPC Program development framework , The convenience it brings is that it can be directly based on it, just Focus on process code writing .

Java field ：

Conventional webservice frame ：Apache CXF、Apache Axis2、java Self contained JAX-WS wait .webService Most frameworks are based on Standards SOAP agreement .

Emerging microservice framework :Dubbo、Spring cloud、Apache Thrift wait .

Why use RPC

As a service

reusable

Interactive calls between systems

RPC Core concept terms

1. Client 、Server、calls、 replies、 service,programs,procedures,version,marshalling（ marshalling ）、unmarshalling（ Disaggregation ）
2. A network service consists of one or more remote assemblies
3. A remote program implements one or more remote procedures
4. The process 、 The parameters of the process 、 The results are defined in the program protocol specification
5. Protocol changes for compatible programs 、 A server may support multiple versions of remote programs .
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