Why webservice ,wcf and web api?

The purpose of all are same , means all solves a single issue , that is why to write the same logic in each application when all needs the same data.

now understand it.

1.There is a mobile application it needs to display all students result of a school.

2.There is a web application it also needs to display all students result of the same school.

 

now when you as developer will start creating the mobile app , you can choose android as platform , but to get data from database , you will have to write some logic , and at last you will create some UI and display the records. (Note you just need data and then you are free to design UI how you like)

 

again , you have to create the same application but this time a web application , so you selected asp.net MVC as platform , what will you do you will again write the logic to retrive data from database then you will create UI and display the records.

 

Thus , just to get the data , and not only for get but anything on data like insert, update etc , you endup creating methods with the same logic in different different platform , why? just because the language you can't use the code written in java directly to a web app written in .Net.

 

why different platform don't understand all language?

This is because of data types and their compilation mechanism , all platform compiles code differently and generate different types of platform specific bytes.

 

Now to resolve the above issue , we needed a common language which could be understand by any platform , that was XMl and JSON, these two format can also carry information as a Message or representation , now the problem got solved , you can send data in XML or Json format which is understand by every platform.

 

So atlast we needed a technolgy in which we could create our methods which will carry data as a representation or XML message , that technolgies are what you mentioned.

 

now , everything evolves overtime when we start getting the drawbacks , same applies here , something was missing with web services so WCF came , again someting was missing with WCF so web api came.

 

I explained the concept just to keep things simple , in reality things are not that simple , but the core is absolutely what i explained.

hope you got the point.

Most software applications run on client devices (computer, laptop, tablet, phone) such as a Website, Windows application, or a mobile app. When an application needs to access data or do some operations on backend, there needs to be a way for the application to connect to the backend. In case of a database that may be store somewhere in cloud or server and hosted somwhere else. Another use case is, there is a mobile app and on some action, the app needs to send an email. This can be done using a Web API or Web service. Web API or Web services are independent of platforms, what applications calls them and so on.

 

WCF (Windows Communication Foundation) was an older technology to build web services. New way is Web API.

 

Here is a good article to learn more about Web API.

 

https://www.c-sharpcorner.com/article/web-api-in-asp-net/ 

Hi,

Please take a look.

 

https://www.dotnettricks.com/learn/webapi/difference-between-wcf-and-web-api-and-wcf-rest-and-web-service