# Deploying another application as subdomain

**URL:** <https://www.ruby-forum.com/t/deploying-another-application-as-subdomain/103184>\
**Category:** Rails\
**Created:** [May 2, 2007, 7:26pm UTC](https://www.ruby-forum.com/t/deploying-another-application-as-subdomain/103184 "2007-05-02T19:26:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![dorelal](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3da27b/32.png) [@dorelal](https://www.ruby-forum.com/u/dorelal)\
**Post date:** [May 2, 2007, 7:26pm UTC](https://www.ruby-forum.com/t/deploying-another-application-as-subdomain/103184/1 "2007-05-02T19:26:54Z")

</div>

Let’s say that I have an application up and running at [http://eii.com](http://eii.com)

I and developing another application that is complimentary to [eii.com](http://eii.com)  
and  
have decided to serve that application using [http://services.eii.com](http://services.eii.com)

Now this is a totally different application but is useful to the people  
visiting [eii.com](http://eii.com) site. This new application has it’s own database and  
own  
source code.

My problem is login part.

If a user logins to [eiil.com](http://eiil.com) and then visits [services.eii.com](http://services.eii.com) how do I  
know  
who the user is and if the user is logged in or not? Should I use  
cookie  
for this purpose then the someone can change the user\_id in the cookie?

Thanks