Synchronize Liferay and External Database

[tan quoc nguyen, modificado hace 14 años.]

Dear all,
I have a big problem about database in liferay.
I have a external database which contain user's information (username, pass, or group...)
Could you tell me how to liferay authenticate with this database. where to config? where to customize coding?
and more thing is How to synchronize this database with liferay (when edit account in liferay, external database will change follow)

I use liferay 5.2.2 with tomcat 6.0.18 (release)

Please help me
Thank a lots

[Eric Min, modificado hace 14 años.]

I have a question:
What do you mean by extenal DB? Whether you want use LDAP synchronize with Liferay.