What is the Client Server Model? | System Design Concepts

Summary

This video script delves into the client-server model, a fundamental concept for developers. It explains the roles of clients, which request information, and servers, which provide it, often through APIs using HTTP. The script also contrasts this centralized model with the decentralized peer-to-peer model, exemplified by torrent networks. The video aims to educate viewers on how information is exchanged over the internet.

Takeaways

• 🌐 **Client-Server Model Definition**: The client-server model is a fundamental concept for understanding how machines communicate and exchange information over the internet.
• 💻 **Client Roles**: Clients can be web browsers, mobile devices, or programs that request information from servers, similar to customers ordering in a restaurant.
• 🔌 **Server Functions**: Servers act as providers of information, which can be stored locally or accessed from other systems, such as databases.
• 📡 **Communication Protocol**: Clients and servers communicate using network protocols, with HTTP being the most common.
• 📱 **Client Diversity**: Clients are diverse, including browsers, devices, and programs, all of which interact with servers to request data.
• 📚 **Server-Database Connection**: Servers are often connected to databases, retrieving data from them in response to client requests.
• 🔗 **APIs as Contracts**: Application Programming Interfaces (APIs) serve as contracts between clients and servers, defining how information is requested and provided.
• 🔁 **Request-Response Cycle**: The client-server interaction involves clients making requests and servers responding with the requested data or performing operations.
• 🌐 **Centralized vs Decentralized**: The client-server model is centralized, with servers holding authoritative information and clients being decentralized requesters.
• 🔄 **Peer-to-Peer Alternative**: The peer-to-peer (P2P) model contrasts with the client-server model by having each participant act as both a consumer and producer of information, without a central server.

Q & A

What is the client-server model?

The client-server model is a concept in computing where a client, which can be a web browser, a mobile device, or a program, requests information from a server, which is the provider of information. This model is fundamental to how machines communicate and exchange data over the internet.

What are the common examples of clients in the client-server model?

Common examples of clients include web browsers like Firefox, Chrome, or Safari, mobile devices such as iPhones or iPads, and programs written in languages like Python, Java, or C++ that run on a computer.

How does a client communicate with a server?

A client communicates with a server using a network protocol language, with HTTP (Hypertext Transfer Protocol) being the most common one. The client makes a request to the server, which then responds with the requested information.

What is the role of a server in the client-server model?

In the client-server model, the server acts as the provider of information. It may have access to information stored locally or it may know how to retrieve it from another source, such as a database. The server also exposes APIs (Application Programming Interfaces) that define the contract for how clients can request information or services.

What is an API in the context of the client-server model?

An API (Application Programming Interface) in the client-server model is a set of rules and protocols for building and interacting with software applications. It defines how clients can request information or services from a server, and what data the server will return in response.

How does the client-server model facilitate the exchange of data over the internet?

The client-server model facilitates data exchange by allowing clients to make HTTP requests to servers. The server then retrieves the requested data, possibly from a database or another server, and returns it to the client via APIs, fulfilling the contract established by the API.

What is the centralized approach in the client-server model?

The centralized approach refers to the concept where servers act as the single source of authoritative information in the client-server model. Clients are decentralized and exist anywhere on the internet, but they rely on centralized servers to provide data and functionality.

What is the difference between the client-server model and the peer-to-peer model?

In the client-server model, there is a clear distinction between clients that request information and servers that provide it. In contrast, the peer-to-peer model is decentralized, with each participant acting as both a consumer and a producer of information, sharing equally in the network.

How does the peer-to-peer model work?

In a peer-to-peer model, each participant in the network can both request and provide data to other participants. There is no central server; instead, participants share resources and information directly with each other, as seen in networks like BitTorrent.

Why is the client-server model essential for developers?

Developers need to understand the client-server model because it is fundamental to building applications that communicate over the internet. Whether they are building client components, server components, or something in between, this model is crucial for how applications interact and exchange data.

What are some alternatives to the client-server model mentioned in the video?

The video mentions peer-to-peer (P2P) as an alternative to the client-server model. In a P2P model, there is no central server; instead, each participant acts as both a client and a server, sharing resources and information directly with others in the network.

Outlines

00:00

🌐 Introduction to the Client-Server Model

The paragraph introduces the concept of the client-server model, which is fundamental to how machines communicate and exchange information over the internet. It emphasizes its importance for developers and those aspiring to be developers, as it is integral to building applications. The video's agenda includes defining the roles of clients and servers, explaining their relationship and how they work together, and discussing alternatives to the client-server model. Clients are described as entities that request information, such as web browsers, mobile devices, or programs, while servers are the providers of information. The paragraph uses the analogy of a restaurant to explain the client-server relationship and mentions HTTP as the common protocol for communication between clients and servers.

05:00

🔗 How Client-Server Interaction Works

This paragraph delves into the mechanics of the client-server interaction. It explains that when a client calls an API, the server retrieves information, possibly from a database or another server, and then returns it to the client. The client can then display this information to the user, who can take actions that lead to further requests. The paragraph highlights the internet's reliance on this model for information exchange and contrasts it with a centralized approach, where servers hold authoritative information and clients are decentralized. It also introduces the peer-to-peer (P2P) model as an alternative, where each participant acts as both a consumer and a producer of information, without a centralized server. The paragraph concludes by summarizing the client-server model's role in providing internet functionality through API calls and data exchange.

Keywords

💡Client-Server Model

The Client-Server Model is a foundational concept in computer networking where a client requests information from a server, which then provides the requested data. In the video, this model is essential to understanding how machines communicate and exchange information over the internet. The client can be a web browser, a mobile device, or a program, while the server is typically a more powerful computer or system that manages and stores data. The video uses the analogy of a restaurant to explain this relationship, where the customer (client) orders (requests) food, and the restaurant (server) provides it.

💡Client

A client in the context of the Client-Server Model is any software or device that requests data, services, or resources from a server. Clients can be web browsers like Firefox or Chrome, mobile devices such as iPhones or tablets, or even programs written in languages like Python, Java, or C++. The video emphasizes that clients initiate communication by making requests to servers, which is central to the client-server relationship.

💡Server

A server in the Client-Server Model is a system that provides data or services to clients. It can be a physical machine or a virtualized service within a machine. Servers are the providers of information and are often associated with databases from which they retrieve data in response to client requests. The video explains that servers expose APIs, which define how clients can interact with them, and that servers do not need to store all information locally but can access it as needed.

💡API (Application Programming Interface)

An API is a set of rules and protocols for building and interacting with software applications. In the video, APIs are described as contracts between the client and server, defining how a client can request information or services from a server. APIs allow clients to call specific functions or services provided by the server without needing to understand the underlying implementation. The video mentions that servers expose APIs, which are crucial for the client-server interaction.

💡HTTP Request

An HTTP Request is a message sent from a client to a server to request access to a resource located on the server. Hypertext Transfer Protocol (HTTP) is the foundation of data communication for the World Wide Web. In the video, HTTP requests are used as an example of how clients communicate with servers to request information, which is a common method for web browsing interactions.

💡Centralized Approach

A centralized approach refers to a system where a central authority or server manages and controls data and services. In the context of the video, the Client-Server Model is described as centralized because the server acts as the single source of authoritative information, while clients are decentralized and can be located anywhere on the internet. This centralized model is contrasted with the peer-to-peer model, where there is no central authority.

💡Decentralized

Decentralized, in the context of the video, refers to a system where there is no central authority or server. This term is used to describe the Peer-to-Peer (P2P) model, where each participant acts as both a client and a server, sharing and consuming resources equally. The video contrasts this with the centralized Client-Server Model, highlighting the differences in how information is shared and managed.

💡Peer-to-Peer (P2P)

Peer-to-Peer (P2P) is a network architecture where each participant shares equal responsibilities and shares resources directly with other participants. The video uses BitTorrent as an example of a P2P network, where each user can both request and provide pieces of a file to others in the network. This model is decentralized, with no central server managing the data flow, unlike the Client-Server Model.

💡Database

A database is a structured set of data stored on a server, which can be accessed and managed by applications and users. In the video, databases are mentioned as a common resource that servers interact with to retrieve and store data. Servers often act as intermediaries between clients and databases, providing access to data through APIs and responding to HTTP requests.

💡Information Exchange

Information exchange is the process by which data is shared between clients and servers in the Client-Server Model. The video explains that this exchange occurs through APIs and HTTP requests, with clients requesting data and servers providing it. This exchange is fundamental to how the internet functions, enabling the flow of data between various devices and systems.

💡Network Protocol

A network protocol is a set of rules that define how devices on a network communicate with each other. In the video, HTTP is mentioned as the most common network protocol used by clients to request information from servers. Network protocols like HTTP enable clients and servers to understand and fulfill each other's requests for data and services.

Highlights

The client-server model is essential for understanding how machines communicate and exchange information over the internet.

Developers need to know the client-server model to build applications with client or server components.

Clients in the client-server model are entities that request information, like web browsers, mobile devices, or programs.

Servers provide information and can be physical machines, virtual servers, or a concept representing data providers.

Servers are often tied to databases and retrieve information from them when requested by clients.

Servers expose APIs, which are application programming interfaces that define how clients can request information or actions.

Clients make HTTP requests to servers to get information, using protocols like HTTP.

The client-server model involves a client making a request and a server responding with the requested information.

Clients don't need to know the details of how servers operate; they just need to know how to request what they want.

Servers can communicate with other servers or databases to fulfill client requests.

The client-server model is centralized, with servers as the authoritative source of information.

Centralized servers are key to the client-server model because they provide the data necessary for rich functionality.

The peer-to-peer (P2P) model is a decentralized approach where each participant acts as both a client and a server.

In P2P networks, participants can request data from and provide data to each other, unlike the centralized client-server model.

The client-server model enables the internet to have rich functionality by allowing data exchange through APIs.

The video provides a comprehensive overview of the client-server model and its importance in modern computing.

Transcripts

what is going on everyone in this video

we are going to be talking about the

client server model and the client

server model is an extremely important

concept in terms of

how machines communicate with each other

and how they exchange

information over the internet if you're

in it

or if you're a developer or you're

looking to become a developer

the client server model is an essential

concept that you need to know about

because you're going to be using it when

you're building your applications you're

either going to be building client

components or server components

or perhaps something in between so in

terms of the agenda for this video

first we're going to briefly just define

what the client and server

are in the context of the client server

model then i'm going to go over the

relationship between these two

components and how the client server

model works

and then finally we're going to talk

about some of the alternatives to the

client server model

towards the end of the video so that's

what we're going to be talking about so

let's get right into it

and over here on the left i already have

kind of the icons that are

giving you a clue as to what i'm talking

about here but as you can imagine

all of these things on the left hand

side of your screen over here these are

all

clients so clients can be in this case

web browser so you know firefox browser

chrome or safari they can be

something like an iphone or an ipad or

some kind of tablet device

or they can be a program such as a

python java or c

plus plus program that is running on

your computer

so clients in in this context in the

client server model

are the ones that are requesting

information they need

they want information they want to get

it from somewhere and that's how they

get the name the client you know like if

you go into a restaurant and you order

something you want something you're the

client

and the restaurant is the resource and

that's where the the server kind of

comes in

so in the client server model the

clients are any of these three things

they could be browsers devices or even

programs that are running on other

computers

but the common thing between them all is

that generally they speak to servers

in some kind of network protocol

language http is probably the most

common one these days so these are some

different examples of

clients in the client server model so

just to reiterate they want to

get information from somewhere else now

the next obvious question

in this is where is that something else

or what is that something else

and that's where the server comes in the

server

and the server doesn't necessarily have

to be a

single physical machine it's more of a

concept

so if it helps you you can imagine it as

like a physical

machine like a physical computer that's

that's receiving traffic but it doesn't

necessarily have to be that it could be

different virtual servers that are

within a certain machine

but generally in the client server model

we're just kind of thinking about the

concepts here

uh so the server in this relationship is

the provider of information

so let me just write that out for you so

the server is often called

the provider provider

and it's called the provider because it

has access to some kind of information

it doesn't necessarily need to have that

information stored locally it could just

know how to get it or where to get it

from

that's basically the role of the server

so typically what you see these days is

that a server usually

is tied to some kind of database

somewhere that may exist on some other

system

and then say this this blue icon here is

your database and then when a request

comes into the server it just goes and

retrieves that from the database

and then grabs that data the database

responds and then the server kind of

responds with that information back to

the client but we're going to go over

that whole relationship in just a moment

uh so that server exposes a set of apis

also known as application programming

interfaces

uh think of this like the contract in

which if you give me something i'll give

you something back

uh that's what an api essentially is if

you want more detail on an api i have a

whole video on that

i'll put that in the description section

below but in the

client server model i think we're moving

on to the next section now

um in the client server model the server

provides the client wants something

and you have this kind of dance that

goes on between them

the client requests information

generally through what's called a http

request

http request which stands for hyper text

transfer protocol so the general theme

is that you have these clients over here

and these clients make requests to a

server and the server receives that

request goes out and grabs it maybe from

a database

it's also possible that this server here

talks to another server and it goes and

gets some information

from that server and then maybe this

server queries a different database

but the general idea is that this server

through its apis just put a little box

here

to denote that it exposes apis uh

it knows how to go and get information

or perform some kind of operation

that is agreed upon or known by the

client

and the client doesn't necessarily need

to know how the server works or how it

does its job or where it stores its

information

or any of the details here the client

just needs to know who do i call to do

what i want to do

and what do i get back from the server

now now completing this example when the

client calls this api

the server is going to get that

information it's going to maybe query

some database call another server like i

already said

and return that information back to the

client

and then the client can observe that

information it can show some uis or some

user interfaces or some buttons on the

screen

and then the client or the user can

perform some other kind of action that

makes another request to a different

server

so this is generally how the client

server model works you have your clients

which are usually browsers programs or

some kind of input devices you have

servers that are listening

for traffic on certain ports they have a

contract or an api

associated with them and when that api

is called

the server knows how to perform a

certain job and return

results back to the client and this is

how the internet works it's how

information travels between

you know the the device in your pocket

and a server sitting somewhere

in the internet it could be anywhere in

the world but as long as your client

knows how to talk to a server

you know it doesn't matter where that

server is located as long

as this contract is being upheld and a

term that usually goes hand in hand with

a client server model

is what's called the centralized

approach or

centralized framework and they're called

centralized because these servers

are the kind of single source where all

this information this authoritative

information

is located and the clients are kind of

decentralized in this relationship

they are existing anywhere on the

internet but the servers are the ones

that are really the

the key to this relationship because

they are the data providers and without

data you can have rich functionality

i mean if you think about it if you're

logging into your bank's website through

you know your firefox browser or

something

your browser itself doesn't allow you to

do that much the only way that you get

rich information you get rich

functionality out of using your browser

is by interacting with servers on the

banking systems network

so that you can go and get the account

balance and pay bills and do all these

different things

so in this way it makes sense to think

of the server as the centralized

component in this relationship

and the opposing concept or the opposing

philosophy in contrast with the

centralized approach

is what's called the p2p or peer-to-peer

peer to peer

and let me just scroll down a little bit

maybe make a little bit more room here

and the peer-to-peer approach is what

you would think of

in terms of like a bittorrent network or

a torrent network so

you have different folks that all

download a torn file and if you don't

know how torrents works like this is

essentially how it works i'm going to

explain it to you right now

so there's multiple people that download

this torrent file so maybe there's like

three actors in this story

so each person in this relationship that

has downloaded this file

acts as both a consumer and a producer

so they

are in our client server model both a

client and a server of information

so with every other participant in this

relationship you

can request data from a different

participant and you can also receive

requests for data that you have

and this is why it's kind of a

peer-to-peer relationship everyone else

that is in this network

can kind of feed off of each other so

that there's no

centralized approach one there's no one

key player in this relationship

that holds all the goods and that's what

we saw in the server model

so this is how it's different the

peer-to-peer model is decentralized

everyone shares an equal role everyone

is both a producer and a consumer

um so this is the idea of the client

server model

and just to recap we have the clients

like your browser your phone or just

programs in general

that are the requesters of information

we have these servers which are the

resources or the providers of

information

and data is exchanged through apis in

which the client

calls a particular api on a server that

is listening on a particular port

and the server responds with that

information and that's how the internet

gets awesome functionality

so i hope you enjoyed this video i have

another great one on apis which you

should check out on the right

here and as always if you like this

please don't forget to like and

subscribe and i'll see you next time