PHP || Client server architecture || 12TH STD Computer applications || CHAPTER -4 смотреть онлайн

In this fast moving world everything has become internet based...shopping has become online shopping the food we eat get delivered home ...most of the businesses are web based ....everything is an examples of internet in daily life.
Tim Berner lee developed the concept of world wide web.This made every business man to use internet as a medium to do business.When people started using web based application there raised a need for an efficient programming language for the servers in the network to communicate.
So many languages were developed and PHP was an answer to it.
PHP is server side scripting language. Before studying about php,you should know how your internet works and what are the elements of it.
The Google you see is similar to big library.when you search for something in it.First Google will search all the data relevant to your search and it will give you back all the relevant information that it has ,for the data you searched.
For example when you search the word php in google u will select a list of hundreds of websites with information about php,from that you can select the required website...when u click the website it will take you the server on which the data you requested to show is stored.
That machine in which all the information are stored will be called as server and your computer which receives the information will be called as client.Now this server will give you the information you requested. This is how internet works.
In this process we saw two machines one is server and another one is client.Php is a language used in server side..so,it is called server side scripting language. It could be embedded with html and used.
It is used to create dynamic webpages.
For efficient execution of PHP,server needs a software to be installed on the it's device.These software are called as web servers.Webserver uses HTTP and serves webpages to the user efficiently.
Client server architecture:
Client server architecture is used with the purpose of sharing information between two different hardwares.
Client and server are the two important component of this architecture.
Client
Client is a high performance machine.
To understand it better,let's see an example of radio station...here a user named Anu is listening to this Rainbow FM...apart from many others users can also can share Rainbow FM.
Here Rainbow FM works concurrently for many users. So,it is a server and all the users connected to it will be considered as clients.
From the example we can understand points about Server.
Server is a high performance machine.
It could run more than one application concurrently.
Client:Client is a separate hardware machine which is connected to the server.As server provides data to client it is also called as Service provider
And the client is called as Service requester.
Client server architecture is generally of three types.
One tier architecture
Two tier architecture
Three tier/ Multi tier architecture
One tier architecture:
In one tier architecture,the client and server lies inside the same machine.
The data that client request for will be searched and provided by the database server which is inside the same computer.
Two tier architecture:
In two Architecture ,client and server works on different Computers.
It has two layers of interaction.
Client is one tier and the server is another tier
Three tier architecture:
In three tier architecture,
Client will be in one tier , server will be in another tier and in between them business logic layer is present .since it involves three layers of interaction ,it is called three tier architecture.
If more number of business layers are used in-between then it is called N- tier architecture.Depending upon the need of software ,the number of logic layers needed in-between will be decided.