Glassfish realms

I have been able to set up spring security (for icefaces) following an example that uses this:

Code:

---

<authentication-manager alias="authenticationManager">
        <authentication-provider>
            <user-service>
                <user name="joe.blow@icesoft.com" password="pass1234" authorities="ROLE_READER"/>
                <user name="ben.simpson@icesoft.com" password="pass5678" authorities="ROLE_READER"/>
            </user-service>
        </authentication-provider>
    </authentication-manager>

---

http://wiki.icefaces.org/display/ICE/Spring+Security

Before I tried integrating Spring Security, I simply used Glassfish's file realm to manage users. Is there a way to continue using the Glassfish file realm and also integrate spring?

I'm under the impression that I need an authentication provider that'll point to the file realm somehow.