How to add custom domain functionality in java based web application?

Question

I don't know how Google Blogger & Google Apps & Google App Engine allows us to add our own custom domain. How such a functionality is implemented ?

How can it be implemented in our own java based web application ?

Say I want to setup a blog application which is hosted on myapp.com but it will allow to end user setup somesite.com.

Answer 1

It's a combination of two things:

• multiple DNS entries
• virtual hosts

Answer 2

There are three parts to such a solution:

• You must have a way for your custom domains to resolve their names to your application (DNS).
• Your web server must respond to requests for each configured domain (virtual hosts).
• Your application must provide content conditionally based on the request domain (e.g. by checking the "Host" request header).