code: private String _getUniqueKey()
  	{
  		StringBuilder b = new StringBuilder();
  		b.append( service );
  		b.append( "#" );
  		b.append( method );
  		if( params != null )
  		{
  			b.append( "#" );
  			b.append( params.toString() );
  		}
  
  		return b.toString();
  	}
docs: calculate the unique key of that request