How to resolve "ORA-00018: maximum number of sessions exceeded" issue

While working with WSO2 G-Reg which was connected to an Oracle DB, we came across and issue where the maximum number of connections were exceeded. 

To get over this exception, we had to increase the number of sessions, processors and transactions as below. 

I found this great blog which explains everything in detail. 

http://nimishgarg.blogspot.com/2011/11/ora-00018-maximum-number-of-sessions.html

 sql> alter system set processes=500 scope=spfile;
 sql> alter system set sessions=555 scope=spfile;
 sql> alter system set transactions=610 scope=spfile;
 sql> shutdown abort
 sql> startup