Data is transmitted and received over HTTP. HTTP is a stateless protocol. A stateless protocol does not require the server to retain session information or status about each communications partner for the duration of multiple requests.
A connection with the a server is opened, data is transmitted to the server (the request), data is received from the server (the response) and the connection is closed again.
This approach allows a web server to process a large number of requests. This can run up to thousands of requests per second.
The requests-per-second processing capacity of a web server depends among other things on:
- The size of the request- and response-data and the time it takes to transmit the data;
- The size of the request- and response-data and the amount of RAM available in the server;
- The time it takes to retrieve data from the database, and the time it takes to update the database;
- The processing power of the server hardware.
If a web server has a large number of clients sending request to it, you need to limit the number of records/rows and columns that are transmitted. You also have to avoid long-running SQL scripts.