Communications between servers
Tags: devops, servers, communications, architecture
Published: 2023-04-02 08:39:58

In today's interconnected world, communication between servers is essential for businesses to operate smoothly. Whether it's transferring data, executing commands, or exchanging messages, there are several ways to communicate between servers. This article will discuss the most common ways to communicate between servers and the protocols on which each one is based.

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## Protocols

### HTTP/HTTPS
The Hypertext Transfer Protocol (HTTP) and its secure version (HTTPS) are the most common protocol for server communication. They are used to exchange data between web servers and clients, and can also be used for server-to-server communication. HTTP and HTTPS are best suited for web-based applications and APIs.

### FTP/SFTP
The File Transfer Protocol (FTP) and its secure version (SFTP) are commonly used for transferring files between servers. FTP is best suited for transferring large files or batches of files that do not need to be transmitted in real-time.

### SSH
Secure Shell (SSH) is a protocol for securely connecting to remote servers and executing commands. SSH is best suited for managing servers and executing commands on them.

### TCP/IP
Transmission Control Protocol (TCP) and Internet Protocol (IP) are the most common protocols for transferring data between servers over the internet. TCP/IP is best suited for real-time applications that require fast, reliable communication.

### UDP
User Datagram Protocol. It is a connectionless, lightweight transport layer protocol that is used to send and receive datagrams over a network. UDP is a member of the Internet Protocol (IP) suite, and it is often used in applications where speed and efficiency are more important than reliability.

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## Technologies

### Message Queues
Message Queuing provides a mechanism for asynchronous communication between servers. Message Queues can be used to decouple processes, distribute work across multiple machines and recover from failures. Message Queues are best suited for applications that require high reliability and fault tolerance.

### WebSockets
WebSockets are a protocol for two-way communication between a client and a server over a single TCP connection. WebSockets can be used to provide real-time communication between servers. WebSockets are best suited for applications that require real-time data exchange, such as online games, chat applications, and financial trading systems.

### API calls

- **REST** (Representational State Transfer) is an architectural style for building web services that uses HTTP methods to retrieve and manipulate data. RESTful APIs are commonly used for communication between web services.
- **SOAP** (Simple Object Access Protocol) is a messaging protocol that defines how XML-based messages are exchanged between web services. It uses XML to encode the message and HTTP as the transport protocol.
- **GraphQL** is a query language for APIs that was developed by Facebook. It allows clients to specify the data they need and receive only that data, reducing the amount of unnecessary data transfer between services.

### Remote Procedure Calls (RPC)
RPCs allow one server to call a method on another server as if it were a local method call. RPCs can be implemented using various protocols like HTTP, TCP, and UDP. RPCs are best suited for applications that require high performance and low latency, such as scientific simulations and financial trading systems.

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In conclusion, there are several ways to communicate between servers, and the choice of communication method depends on the specific use case and the requirements of the system. Message Queues, WebSockets, API calls, and RPCs are all viable options depending on the application's needs. By understanding the strengths and weaknesses of each communication method, businesses can choose the most appropriate one for their specific use case, resulting in faster and more reliable communication between servers.