What Is Client-Server Architecture?

Whenever people open their computers to visit a website, fill in a spreadsheet, or send an email, they rely on a complex digital network to ensure those tasks happen seamlessly and efficiently. This network is a client-server architecture designed to create a positive user experience for anyone interacting with the internet or other large-scale digital databases. 

Client-server architectures work across various industries and businesses to facilitate efficient communication between users and servers. It helps individuals easily access, share, and secure information.

By learning more about client-server architecture and what makes client-server networks successful, you can deepen your understanding of how this model works. You’ll also discover which model may be most beneficial for your company.

What is client-server architecture?

Client-server architecture refers to a network where many devices connect to a centralized server, allowing users to access different stored data and perform diverse tasks simultaneously. The client refers to the person or device requesting information, and the server refers to the device that provides this information. Client-server architecture follows a protocol known as request-response, which means the client requests information or data, and then the server provides the requested data. This pattern involves specific rules, guidelines, and languages to ensure it’s standardized across different types of servers. It provides a seamless user experience regardless of users' device to connect to the server. 

For example, the client might visit a website. When that person enters the URL they want to see, the server requests and displays the website domain. Other operations operate similarly. When you send an email, you essentially request the email server transmit your email to the intended recipient. This format also enables more advanced security measures. If you send a request that goes against what the server allows, the server can reject your request.

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Characteristics of client-server architecture

While you can have different styles of client-server architecture, many have similar core features. Common characteristics you might see include:

• The architecture uses a request-response pattern while following the requisite rules and protocols.

• The architecture has vertical and horizontal scalability. The network can easily add or remove servers (vertical scaling) or user workstations (horizontal scaling) without compromising functionality. 

• Multiple devices or workstations connect to one central server simultaneously, accessing the same resources if needed.

• Servers typically provide services such as file storage and sharing, as well as printer and application access.

• The architecture uses a network protocol to make it easy for devices to communicate quickly and efficiently.

Types and tiers of client-server architecture

Professionals sort client-server architecture by the types of requests and tasks the system can handle. These tiers of client-server architecture include the following:

One-tier architecture

Tier one architecture is an all-in-one architecture. It stores all the information required for the server to function inside one package. These settings often include the user interface, database logic, business logic, and database settings as one layer on a shared drive. Smaller networks, for example, typically rely on tier one architecture.

Two-tier architecture

Two-tier architecture breaks the user interface and database into separate servers and layers, allowing clients to make outside requests. Like online reservation systems, this architecture is popular for sending and retrieving contract information.

Think of this like ordering at a coffee shop. You (the user) tell the barista (database server) your order, and they make your drink to your specifications. While this is effective with a small volume of traffic in the coffee shop, it may cause delays if you have a long line of customers with complex orders.

Three-tier architecture

Three-tier architecture introduces middleware into the client-server architecture. The middleware offers better security and the opportunity to handle more complex tasks and requests. The layers are divided into a presentation layer, a database layer, and an application layer.

Continuing the coffee shop example, you can think of this as placing your order (user request) with a cashier (application layer), who then gives your order to the baristas (database server) to make the drink. Given the higher number of customers, dividing tasks and creating a more streamlined system to receive orders and provide drinks becomes essential.

N-tier architecture

N-tier architecture adds additional middleware layers to create more complex client-server systems that handle more varied types of network traffic and tasks. This client-server architecture is desirable for any organization because it is flexible and scalable. 

In an N-tiered coffee shop, you would see several layers of cashiers, waitpersons, baristas, and even shop managers who work together to take orders, collect ingredients, prepare drinks, and deliver coffee to customers.

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Major components of client-server architecture

Client-server architectures typically consist of the following major components:

• Clients: Also known as server requesters, clients can be personal computers, workstations, or other smart devices that send requests to the servers and then receive the information.

• Servers: Servers are large devices used to store and process files, databases, and programs. You can work with several types of servers, such as application servers, database servers, web servers, and computing servers.

• Networking devices: These devices connect the workstations and servers and allow them to communicate and send information effectively. Examples of networking devices include hubs, bridges, switches, gateways, and routers.

Examples of client-server architecture

Businesses use client-server architecture to facilitate professional and casual interactions between clients and servers. Some examples of when you might use client-server architecture include:

• Email server: Client-server architecture facilitates the sending and receiving of emails.

• Domain Name Service (DNS) server: This type of client-server architecture hosts websites and allows users to access them daily.

• File servers: This client-server architecture supports structures like the cloud, where users store and interact with documents, spreadsheets, presentations, videos, and more.

• Application servers: These servers allow you to access applications on the internet without downloading a copy of the application to your device.

Pros and cons of client-server architecture

Client-server architecture has many benefits for business networking. One is the ease of managing it because one single server hosts the needed files. Another is that it allows different platforms to share resources, making accessing and sharing important information more efficient. 

Because the servers are scalable, a business can tailor its architecture to match its organization’s size, growth, and needs. This type of structure is key for creating easily usable interfaces that provide clients with needed information regardless of company size. As the organization grows, the server size can seamlessly expand without disrupting current usage.

However, client-server architecture also has drawbacks, which are essential when choosing the proper structure for your needs. Because servers run continually, they require constant management and maintenance, including updates and network troubleshooting. Servers also run hot, so they often require a separate room for storage. Both of these things can be expensive over time. 

In addition to maintenance and storage, if too many users try to request data at once, the network becomes congested and runs more slowly. Large businesses should consider this risk, especially when accessing time-sensitive information. Organizations should invest in the server architecture required for their company size and server usage to minimize this risk.

Next steps

Client-server architecture is a common network architecture in which multiple clients can request a centralized server. Users connect to this type of network for tasks such as sending emails, accessing websites, and sharing files. Depending on the organization, different server types and sizes are available to meet business needs efficiently and effectively.

Learn more about client-server architecture and basic foundational IT knowledge with courses and certificates on Coursera. With options like Princeton University’s Computer Architecture course or IBM’s Introduction to Software Engineering, you’ll learn the fundamental components of creating robust, efficient client-server architectures and how to apply them to your business. These courses are also great ways to learn about starting an IT engineering career.