How to get data from database or webservice directly to create our own web screen

How to get data from database or webservice directly to create our own web screen

Hi,
 
Is there a webservice or something else, or direct connection to database to get data.
Forexample i want to get down nodes for category BlockSwitches.
How can i get it without using opmanager console.
I will create my own pages with web programming.
Is it possible to use a webservice, xml etc...
Can i get it from database with a readonly sql user ? or webservice ?

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