How to integrate the observer to Unicorn ?

• In package resource, modify observer.list.
  
  You have to add path to calculator contract (.wadl ans .rdf). There is two ways to add this path :
  First way is to add directory path where .wadl and .rdf are. Unicorn will automatically look for files observer.wadl and observer.rdf.
  Second way is to add two paths : one for wadl file, other for rdf file.
  In our case, we had just '' http://localhost/calculator_contract because ours files are observer.wadl and observer.rdf.