Technology sharing | common interface protocol analysis

Transfer packets between services , Because of different application scenarios , Use different communication protocols for delivery . For example, website access , Often use HTTP Protocol delivery , File transfer usage FTP, Mail delivery use SMTP. The above three types of protocols are in the application layer of the network model . In addition to the common protocols of the application layer , For the transport layer TCP、UDP agreement , as well as Restful Architectural style 、RPC Basic network knowledge such as protocols should be understood and recognized .

Network protocol introduction

Before understanding the specific agreement , You need to know OSI Seven layer model 、TCP/IP Four layer model 、 Five layer architecture these three different network models .

Network protocol model comparison diagram ：

• OSI The reference model is a conceptual framework for developing standards for coordinating interprocess communication , It is not a standard .
• TCP/IP The four layer model is the basic communication architecture of the Internet . It's often seen as a simplified seven level OSI Model .
• The five layer agreement is OSI and TCP/IP The synthesis of , The practical application is still TCP/IP Four story structure of .
• TCP/IP The protocol stack corresponds to TCP/IP The specific network protocol used in the four layer model .

TCP agreement

TCP The protocol is in the transport layer , A connection oriented 、 reliable 、 Transport layer communication protocol based on byte stream .TCP The working mode of the protocol is that... Is required when establishing a connection “ Three handshakes ”, When terminating the connection, you need to “ Four waves ”.“ Three handshakes ” and “ Four waves ” yes TCP Important knowledge points of the agreement , In the following chapters, we will introduce in detail through the combination of practice and theory .

Applicable scenario

TCP Connection oriented protocol 、 Error retransmission 、 Congestion control and other characteristics , It is suitable for scenarios with high reliability , For example, data transmission involving user information .

UDP agreement

UDP Once the protocol sends the data sent by the application to the network layer , Do not keep data backups . It's only in IP Multiplexing and data verification fields are added to the header of the packet . therefore UDP Packets are often considered unreliable .

Applicable scenario

UDP There is no need to establish a connection in advance 、 Implement simple features , It is very suitable for scenes with high real-time performance , Like streaming media 、 Online games, etc .

HTTP agreement

HTTP Protocol is the most common protocol in interface testing , Is for distributed 、 Application layer protocols for collaborative and hypermedia information systems .HTTP Is the foundation of data communication in the world wide web . The client sends... To the server HTTP request , The server will return the requested data in the response . During the test , It is often necessary to verify the request and response results , So understand HTTP agreement , For interface testing , It's the top priority .

In the following chapters, we will introduce HTTP、HTTPS The difference between agreements , as well as HTTP Basic knowledge information of the agreement .

RESTful agreement

origin

Roy Thomas Fielding Doctor Yu 2000 A style of World Wide Web software architecture proposed in his doctoral dissertation in . Its purpose is to facilitate different software to transmit information in the network .RESTful Is based on HTTP A resource request made on top of a protocol 、 The style of operation , To sum up in one sentence is to use URL To locate resources , Use HTTP Verb description operation .

HTTP The request method is RESTful api Typical applications in ：

Method	significance
GET	Access to resources
POST	Add or update
PUT	Update resources
DELETE	Delete resources

Be careful ：  Different companies are using RESTful There are some differences in architectural style .

RPC agreement

RPC The English of is Remote Procedure Call , It's a good interpretation RPC The concept of agreement , That is to realize remote execution by calling local code ,RPC It is mainly used for service invocation within the company .RPC The advantage of the interface is higher transmission efficiency 、 Lower performance loss 、 Built in load balancing strategy 、 Better service governance .

common RPC agreement

Currently commonly used in the industry RPC The main agreements are as follows ：

• Dubbo：Java High performance based on RPC agreement .
• gRPC： High performance general purpose RPC frame , be based on Protocol Buffers.PB It's a language neutral 、 Platform neutral data serialization framework .
• Thrift： And gRPC Similar multilingualism RPC frame .