I'm fairly new to Eclipse, so please bear with me.
I've verified that the PHP script is being run and that it's setting the cookie - it's just not getting to the browser. Is Eclipse blocking the cookies in dev mode for some reason, and is there a way to allow them?
I think I've solved my own problem. I was confusing cookies with php sessions. Since I'm really just creating a PHP session on the server where my PHP files are hosted, it makes sense that the local dev mode where my Java frontend is being executed ignores the attempt to set the cookie.
Rather than looking for the cookie to be set, I need to check the return from my PHP script to verify that a session was created.