INTRODUCTION TO CLIENT SERVER | CLIENT SERVER MODEL (MODULE)

client-server network

designed for end-users, called clients, to access resources such as files, songs, video collections, or some other service from a central computer called a server.

serve its clients

server's sole purpose

Client-server model or Client-server architecture

distributed application framework dividing tasks between servers and clients, which either reside in the same system or communicate through a computer network or the Internet.

client

relies on sending a request to another program in order to access a service made available by a server

server

runs one or more programs that share resources with and distribute work among clients

Client-server communication

communicates in a request–response messaging pattern and must adhere to a common communications protocol, which formally defines the rules, language, and dialog patterns to be used.

TCP/IP

Client-server communication typically adheres to the _________ protocol suite.

TCP protocol

maintains a connection until the client and server have completed the message exchange

TCP protocol

determines the best way to distribute application data into packets that networks can deliver

TCP protocol

transfers packets to and receives packets from the network

TCP protocol

manages flow control

TCP protocol

retransmission of dropped or garbled packets

IP

a connectionless protocol in which each packet traveling through the Internet is an independent unit of data unrelated to any other data units.

organized and prioritized in a scheduling system

Client requests are?

client-server approach

enables any general-purpose computer to expand its capabilities by utilizing the shared resources of other hosts.

• email

• the World Wide Web

• network printing

Popular client-server applications

host

any computer connected to a network

host

a versatile, multifunction computer

User-host

Computer used by a client.

server-host

Computer devoted to serving.

clients and servers

____ and _____ are just programs that run on a host.

server

In the client-server model, a ______ is more likely to be devoted to the task of serving.

"Separating Data from Function in a Distributed File System",

An early use of the word client in a paper on 1978 by Xerox PARC computer scientists Howard Sturgis, James Mitchell, and Jay Israel.

1992

the word server had entered into general parlance

client–server model

does not dictate that server-hosts must have more resources than client-hosts

client–server model

It enables any general-purpose computer to extend its capabilities by using the shared resources of other hosts.

Centralized computing

specifically allocates a large amount of resources to a small number of computers

Centralized computing

More computation offloaded to central computers → simpler client-hosts.

Centralized computing

It relies heavily on network resources (servers and infrastructure) for computation and storage.

diskless node

loads even its operating system from the network

Computer terminal

Only input/output interface to the server.

fat client

a personal computer, has many resources, and does not rely on a server for essential functions.

microcomputers

As _______ decreased in price and increased in power from the 1980s to the late 1990s, many organizations transitioned computation from centralized servers, such as mainframes and minicomputers, to fat clients.

web applications

During the 2000s, _________ matured enough to rival application software developed for a specific microarchitecture.

cloud computing

This maturation, more affordable mass storage, and the advent of service-oriented architecture were among the factors that gave rise to the _________ trend of the 2010s.

client server computing

works with a system of request and response system where the client sends a request and the server responds with information.

common communication protocol

The client and server should follow a ________ so they can easily interact with each other.

application layer

All the communication protocols are available at the _____________

limited number of client requests

A server can only accommodate a ______ at a time.

system based to priority

Client server computing uses a ________ to respond to the requests.

Denial of Service attacks

can disrupt a server’s ability to respond to real client requests by flooding it with false requests.

web server

It returns the web pages to the clients that requested them.

CHARACTERISTICS OF CLIENT COMPUTING

The client server computing works with a system of request and response. The client sends a request to the server and the server responds with the desired information.

CHARACTERISTICS OF CLIENT COMPUTING

The client and server should follow a common communication protocol so they can easily interact with each other. All the communication protocols are available at the application layer.

CHARACTERISTICS OF CLIENT COMPUTING

A server can only accommodate a limited number of client requests at a time. So, it uses a system based to priority to respond to the requests.

CHARACTERISTICS OF CLIENT COMPUTING

Denial of Service attacks hinders server’s ability to respond to authentic client requests by inundating it with false requests.

CHARACTERISTICS OF CLIENT COMPUTING

An example of a client server computing system is a web server. It returns the web pages to the clients that requested them.

Client-server architecture

a computing model in which the server hosts, delivers and manages most of the resources and services to be consumed by the client.

Client-server architecture

This type of architecture has one or more client computers connected to a central server over a network or internet connection.

Client-server architecture

also known as a networking computing model or client-server network because all the requests and services are delivered over a network.

Client-server architecture

It’s considered a form of distributed computing system because the components are doing their work independently of one another.

CHARACTERISTICS OF CLIENT SERVER ARCHITECTURE

Client and server machines need different amount of hardware and software resources.

CHARACTERISTICS OF CLIENT SERVER ARCHITECTURE

Client and server machines may belong to different vendors.

CHARACTERISTICS OF CLIENT SERVER ARCHITECTURE

Horizontal scalability (increase of the client machines) and vertical scalability (migration to a more powerful server or to a multi-server solution)

Horizontal scalability

increase of the client machines

vertical scalability

migration to a more powerful server or to a multi-server solution

CHARACTERISTICS OF CLIENT SERVER ARCHITECTURE

A client or server application interacts directly with a transport layer protocol to establish communication and to send or receive information.

CHARACTERISTICS OF CLIENT SERVER ARCHITECTURE

The transport protocol then uses lower layer protocols to send or receive individual messages. Thus, a computer needs a complete stack of protocols to run either a client or a server.

CHARACTERISTICS OF CLIENT SERVER ARCHITECTURE

A single server-class computer can offer multiple services at the same time; a separate server program is needed for each service

client–server model

describes how a server provides resources and services to one or more clients.

server

have a one-to-many relationship with clients, meaning a single server can provide resources to multiple clients at one time.

• web servers

• mail servers

• file servers

Examples of servers

server

can either accept or reject the connection

server

If the connection is accepted, the _______ establishes and maintains a connection with the client over a specific protocol.

distributed computing

used to spread clients across multiple servers for smooth performance.

client

a computer (Host) i.e. capable of receiving information or using a particular service from the service providers (Servers)

server

a remote computer which provides information (data) or access to particular services.

Advantages of Client-Server Network

Client-Server Network has centralized control. i.e., centralized user accounts, security, and access to simplify network administration.

Advantages of Client-Server Network

It does not slow down with heavy use.

Advantages of Client-Server Network

The size of the network can be expanded to any size.

Advantages of Client-Server Network

Proper Management: All the files are stored in the same place. In this way, the management of files becomes easy. Also, it becomes easier to find files.

Advantages of Client-Server Network

As all the data is stored on the server it's easy to make a back-up of it.

Advantages of Client-Server Network

Reduces Data Replication- Data stored on the servers instead of each client, so it reduces the amount of data replication for the application.

Disadvantages of Client-Server Network

A specialist network operating system is needed.

Disadvantages of Client-Server Network

Server failure leads to the whole network failure.

Disadvantages of Client-Server Network

It is very expensive to install and manage as dedicated hardware (Server) and special software is required.

Disadvantages of Client-Server Network

Professional IT people are required to maintain the servers and other technical details of the network.

Authentication

It is required (email + password) before the server allows access or sends data.

Servers have traffic limits

too many clients can overload a single server

Centralized control

centralized user accounts, security, and access for easier administration

Scalable

network size can be expanded to any size

Proper file management

all files stored in one place, easier to manage and find

Easy backup

all data stored on the server makes backup simple

Reduces data replication

data stored on servers instead of each client

Client: Gmail, Outlook

Server: Gmail/Yahoo Mail Servers

Email

send/receive email messages

Client: Chrome, Firefox

Servers: Apache, Nginx

Web Browsing

Access and display websites

Client: PC, Mobile App

Server: Google Drive, Dropbox Servers

Cloud Storage

Upload/download and sync files

The TCP/IP model and its layers