Thanks to many kind of information.
Now I'm developing a blog site with WP and Mysql.
Then, my customer using a simplex communication network between web server and DB server.
It means the web server cannot call the DB server but the DB server only can call the web server
because of their communication secure policy.
I have found couple of secure solution which can make them possible, but they only work with Java or another language except php.
How can I make WP work under simplex communication network?
If somebody have an idea, pleas contact me.