code: public String startSearch(String appIdentifier, SPFSearchDescriptor searchDescriptor, SPFSearchCallback callback) {
  		QueryInfo queryInfo = mSearchScheduler.registerSearch(appIdentifier, searchDescriptor,callback);
  		mSearchScheduler.startSearch(queryInfo);
  		return queryInfo.getQueryId();
  	}
docs: Start a new search.
  
  @param appIdentifier
  - the package name of the caller app
  @param searchDescriptor
  - a descriptor specifying query and settings
  @return the identifier of the query