Client-server architecture is the fundamental principle of organizing modern information systems. It allows for interaction between client and server components and structures applications at the data exchange level.
Client-server architecture operates on the request-response principle. The client sends a request to the server, and the server processes that request and responds to the client. In this way, the client and server interact with each other through a certain data transfer protocol, such as HTTP or TCP/IP.
Let's consider the main principles and roles when designing client-server systems.
1. The client is the application or device that initiates requests to the server. The client can be of various complexity levels, from a simple web browser to complex mobile applications. The client generates requests to the server, transfers data, and waits for a response.
2. The server is a program or device that processes requests from the client and provides it with the necessary data or services. The server can be a physical device or virtually located on a remote machine. It can also perform specific logic when processing requests, such as conducting calculations or providing access to a database.
3. Protocols are a set of rules and formats that regulate the interaction between client and server. For example, HTTP (Hypertext Transfer Protocol) is used for transferring web pages, and SMTP (Simple Mail Transfer Protocol) is used for sending emails. Protocols define how clients and servers exchange data.
4. Architectural models. There are several different models of client-server architecture, such as two-tier, three-tier, and N-tier architecture. In two-tier architecture, the client directly communicates with the server. In three-tier architecture, an intermediate level called the "application server" is added, which is responsible for business logic. In N-tier architecture, additional levels are added to distribute the load and improve performance.
5. Security is an important aspect of client-server architecture. Since clients and servers exchange data, it is necessary to ensure their protection from unauthorized access and information leakage. Various technologies are used for this purpose, such as data encryption, user authentication, and authorization.
In general, client-server architecture is one of the key concepts underlying modern information systems. It enables effective interaction between client and server, allows for the development of high-performance and scalable applications, and ensures the security of data transmission.