what is SOA ? small query

Question

Hi

 

I have mini doubt on this . Well i just know only few things about this i.e it is a service oriented architecture and everything should be done through service right i guess so .

 

My Doubt :

 

If  i have a MDS services which is related to getting DB content and also MVC4 webapi which is also a service . so thing i am using here is a WCF service between MDS & WEB API . So i am writing the Business logic layer code in WCF itself and mds related code in WCF . . So am i doing it in a right way else

Business layer should be separate and need to consume methods of BLL in wcf ?? 

 

Which is advisable (ps: must fallow SOA)

 

 

Regards