How to Add Federated engine after installing Mysql I have Mysql 5.5.18
and upon show engines:  



show engines;
+--------------------+---------+------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                    | Transactions | XA   | Savepoints |
+--------------------+---------+------------------------------------------------------------+--------------+------+------------+
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES          | YES  | YES        |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                         | NO           | NO   | NO         |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                      | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                         | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                      | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables  | NO           | NO   | NO         |
+--------------------+---------+------------------------------------------------------------+--------------+------+------------+


as you see federated engine is not one of the list. i need to enable it!! any idea of why BLACKHOLE, FEDERATED, and ARCHIVE engines are missing from the list? and how can i add/enable them?
EDIT
I have ubuntu 11.10 and installed mysql from ppa ... i have added the following to /etc/apt/sources.list


deb http://ppa.launchpad.net/nathan-renniewaldock/ppa/ubuntu oneiric main
deb-src http://ppa.launchpad.net/nathan-renniewaldock/ppa/ubuntu oneiric main


Thanks for your help
I have managed to find a solution...
there is a plugin already available at

/usr/lib/mysql/plugin/ha_federated.so

i just logged in to mysql as root and run the following query

mysql>install plugin federated soname 'ha_federated.so';

then i added federated to my.cnf and restarted mysql