Client-Server Model

How does the Browser interact with the Servers?

The browser interacts with servers through a process that involves sending requests and receiving responses. Here's how it works:

• Request Initiation: When you enter a URL or click a link, the browser sends an HTTP request to the server. This request includes details like the type of content needed, cookies, and other data.
   
• DNS Resolution: The browser first queries a DNS server to translate the human-readable domain name (like example.com) into an IP address that identifies the server.
   
• TCP/IP Connection: The browser establishes a connection with the server using the IP address obtained. This connection is usually made through the TCP/IP protocol, ensuring reliable data transfer.
   
• Sending the Request: Once connected, the browser sends an HTTP request to the server. This request specifies what the browser is asking for, such as an HTML page, an image, or other resources.
   
• Server Processing: The server processes the request, retrieves the required data, and prepares an HTTP response. This response includes the requested content and status information (e.g., whether the request was successful).
   
• Receiving the Response: The browser receives the HTTP response from the server. It interprets the content, which could be HTML, CSS, JavaScript, or other resources needed to display the webpage.
   
• Rendering the Page: The browser then renders the received content into the visual webpage that users see, potentially sending additional requests for resources like images or scripts as needed.
   
• Closing the Connection: After the data transfer is complete, the browser may close the TCP/IP connection, although it might keep it open for a short period for potential future requests to the same server (known as keep-alive).

This interaction loop happens rapidly, enabling the browser to fetch and display web content seamlessly.

Advantages of the Client-Server model 

1. Centralization
   The primary benefit of a client-server network is the centralized control it provides. All of the required information is gathered in one spot. This is particularly advantageous for network administrators, who have complete control over management and administration. Any problem that arises throughout the whole network may be resolved in one location. Also as a result of this, upgrading resources and data has gotten a lot easier.
    
2. Safety and security
   Because of its centralized architecture, the data in a client-server network is effectively safeguarded. It can be enforced with access restrictions, allowing only authorized people access. Imposing credentials such as login and password is one such approach. Furthermore, if the data is lost, the files can be retrieved quickly from a single backup.
    
3. Scalability
   Client-server networks have a lot of scalabilities. The user can expand the number of resources such as clients and servers as needed. As a result, the server's capacity may be increased without causing significant downtime. Because the server is centralized, there are no concerns regarding authorization to network resources growing in size. As a result, the arrangements require a small number of people.
    
4. Management
   It is quite simple to handle files because they are all kept on a single server. The optimum management for tracking and finding records of necessary files is in a client-server network.
    
5. Accessibility
   Every client, regardless of location or platform, is given the option to log into the system. All workers will be able to access their business information without the requirement for a terminal mode or a processor in this manner.

Disadvantages of the Client-Server model

1. Congestion 
   The most significant drawback of a client-server network is traffic congestion. Too many clients making requests from the same server can cause the connection to fail or slow down. An overburdened server causes several issues with information access.
    
2. Stability
   Client-server networks, as we all know, are centralized. In the event that the primary server fails or is interfered with, the whole network will be interrupted. As a result, client-server networks are lacking in terms of resilience.
    
3. Cost
   The cost of setting up and maintaining a server in a client-server network is often higher than the cost of network operations. Because the networks are so strong, they can be costly to acquire. As a result, not every user will be able to afford them.
    
4. Maintenance 
   It will work nonstop after the servers are built. That is to say, it must be given the attention it deserves. If there are any issues, they must be handled as soon as possible. As a result, the server needs to be maintained by professional network management.
    
5. Resources
   Not all of the server's resources are available for acquisition. It is not feasible, for example, to print a document straight from the web or to alter any information on the client's hard disc drive.

Must Read Stop and Wait Protocol.

Peer-to-Peer vs Client-server Model

1. Definition
   A peer-to-peer network is a distributed application architecture in which jobs or workloads are divided among peers. A client-server network is a distributed application framework that consists of resource or service providers (servers) and service requesters (clients). This is the distinction between a peer-to-peer network and a client-server network.
    
2. Functionality
   Thus, the main difference between peer-to-peer and client-server networks is that, in peer to peer network, each node can request services and provide services. Whereas, in a client-server network, the client requests for service, and the server responds with a service.
    
3. Type of Network
   Another distinction between a peer-to-peer and a client-server network is that the former is a decentralized network, whilst the latter is a centralized network.
    
4. Reliability
   In a peer-to-peer network, there are numerous service-providing nodes. As a result, it is more dependable. Clients in a client-server network are reliant on the server. All clients' operations will be disrupted if the server fails. This is a significant distinction between a peer-to-peer network and a client-server network.
    
5. Time for service access
   Furthermore, because the service-providing nodes are dispersed throughout the peer-to-peer network, the service-requesting node does not have to wait long. In a client-server network, on the other hand, several clients request services from a server. As a result, a service's access time is longer.
    
6. Cost
   While a client-server network is more expensive to set up, a peer-to-peer network does not require as much gear.
    
7. Security
   In comparison to a peer-to-peer network, a client-server network is more reliable and secure. Another distinction between a peer-to-peer and a client-server network is this.

You can also read about mime protocol and Subnetting in Computer Networks

You can read related articles such as Congestion Control in Computer Networks here.

Frequently Asked Questions

Which layer provides the interface via which client and server application objects communicate? 

The skeleton or stub layer provides the interface via which client and server application objects communicate.

Which is the binary data protocol layer? 

The transport protocol layer is a binary data protocol that transmits requests for distant objects across the wire. Any remote program that talks with these server objects are referred to as a client.

Which object serves as a client-side gateway? 

A stub is a client-side object that functions as a gateway. The stub is used to pass outbound requests.

Which is the server-side object's gateway? 

A skeleton is a server-side object that serves as a gateway. It is where all inbound requests are directed.

Conclusion

In this article, we have studied an introduction to the client-server model, its components, how does client-server model works, what are its examples, and what are its advantages and disadvantages, and a comparison with the peer-to-peer model. 

Recommended Readings:

• Introduction to computer networks
• Mime Protocol
• Telnet
• OSI Model
• TCP/ICP Model 
• OSI v/s TCP/IP Model
• Data Link Layer
• Physical Layer
• Network Layer
• Session Layer
• Presentation Layer
• Application Layer
• Routing and its types in Computer Networks
• Distance Vector Routing Algorithm
• Free Space Management in OS
• Clean Architecture

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