How can I send HTTP requests from SQL Server 2012 to a non-.Net application? I know basic only concepts (DDL,DML queries) of the SQL Server 2012. I explain the workflows of both my application and the database below.

Workflow of the application:

I build web application in Java. Whenever it receives an HTTP request, it fetches data from the database, does some computations on the data and the computed data will be stored in another database.

Before explaining the database workflow, I will explain what a database modification is from my point of view: If any operation happens like creating new tables, data modification, data deletion in tables, etc. indirectly all these are effects on the database.

Workflow of the database:

I have SQL Server 2012. Whenever the database is modified, it will send an HTTP request to the application. The Application runs on an Apache Tomcat server. Once the application receives the HTTP request, it continues that individual workflow.

If you understand my question, we are not sending HTTP requests from a browser (i.e. end-users can't access this application), we are sending HTTP request from SQL Server.

I hope you understand what my question is.

I read some tutorials for this, but I didn't get anything.

Can anyone suggest the correct way of doing this?
You send a request, when you need something back. If you want to let someone to know something, but do not need anything back you notify with a notification. 

There is such a feature called SQL Server Service Broker. It allows communitaion over boundaries of different systems and guarantees consistency and timing of the messages.

Further reading:
 - SQL Server Service Broker  on MSDN
 - SQL Server Service Broker Explained