In terms of integrating Wordpress inside of OSSN, OSSN currently has no feature for that.
However, you can install Wordpress on a subfolder like www.xyz.com/blog and acts just as a regular Wordpress site would. Or even as blog.xyz.com while your main OSSN site is running at www.xyz.com
You can have a Wordpress theme designed to look like your main OSSN site so that whem users click/visit your www.xyz.com/blog, they would feel like they are still on your OSSN site.
Or you can also do the other way around as Wordpress being your main site at www.xyz.com and OSSN as www.xyz.com/community as your community/members site.
Both OSSN and Wordpress installations will operate on a separate databases. However with special plugins or programming you can synch your OSSN users to your Wordpress users and vice versa. You can even show Wordpress posts on your OSSN, and OSSN posts to your Wordpress site. It all depends on how good your programmer is.