Web Applications Client & Server

Figure 1 [1] illustrates the web application architecture in the server side and client side.

Server Side

• Logic Layer
• Implements the application business logic using high-level programming languages, such as Java, PHP, or Python. 
• Web Server Layer
• Receive HTTP request, and passes the request to the appropriate server-side program, e.g., Apache web server, Windows IIS, or Nginx.
• Data Storage Layer
• Stores the web application state and user data. Popular data storage systems are traditional SQL databases, which include MySQL, PorsgreSQL, or MSSQL
• Infrastructure Layer
• Runs the operating systems. An infrastructure could be a physical machine or virtualization platform which manages multiple virtual machines. 

Client Side

The client side receives HTTP response from the server-side, and the job of the client is to convert the HTML contained in the HTTP response into a graphical interface from the user. 

• Logic Layer (Presentation Layer)
• It is written in a combination of HTML, CCS, and JavaScript, with JavaScript providing a way for the sever-side code to execute application logic on the client

• Browser 
• Retrieves the presentation layer code from the server, interprets it, and presents it as a graphic interface to the user. 

• Storage Layer
• For the presentation layer code to store data. Available storage methods include cookies, local storage, IndexedDB, and File APIs.

• Operating System Layer
• Runs the browser

Reference
[1] Toward a Moving Target Defense for a Web Applications, by Marhony Taguinod, in International Conference on Information Reuse and Integration 2015