Structure of a Client Server System

In client-server computing, the clients request a resource and the server provides that resource. A server may serve multiple clients at the same time while a client is in contact with only one server. This architecture forms the backbone of modern distributed systems, web applications, and enterprise software.

The different structures for two-tier and three-tier architectures are given as follows −

Two-Tier Client/Server Structure

The two-tier architecture primarily has two parts: a client tier and a server tier. The client tier sends a request to the server tier and the server tier responds with the desired information.

An example of a two-tier client/server structure is a web server. It returns the required web pages to the clients that requested them. Database applications where clients directly connect to database servers also follow this model.

Advantages of Two-Tier Client/Server Structure

• This structure is quite easy to maintain and modify.

• The communication between the client and server in the form of request-response messages is quite fast.

• Simple architecture makes it cost-effective for small applications.

Disadvantages of Two-Tier Client/Server Structure

• If the client nodes are increased beyond capacity in the structure, then the server is not able to handle the request overflow and performance degrades.

• Security concerns as clients directly access the database server.

• Limited scalability due to tight coupling between client and server.

Three-Tier Client/Server Structure

The three-tier architecture has three layers: client, application, and data layer. The client layer requests the information through a GUI or web interface. The application layer acts as an interface between the client and data layer, providing communication and security. The data layer contains the actual database and data management services.

Advantages of Three-Tier Client/Server Structure

• The three-tier structure provides much better service and fast performance.

• The structure can be scaled according to requirements without any problem.

• Data security is much improved in the three-tier structure.

• Better separation of concerns allows independent development and maintenance of each tier.

Disadvantages of Three-Tier Client/Server Structure

• Three-tier client/server structure is quite complex due to advanced features.

• Higher development and maintenance costs compared to two-tier architecture.

• Network latency may increase due to additional communication layers.

Comparison

Conclusion

Client-server architecture forms the foundation of distributed computing. Two-tier architecture offers simplicity and speed for smaller applications, while three-tier architecture provides better scalability, security, and maintainability for enterprise-level systems. The choice depends on application requirements, budget, and expected system growth.