which schemes

jGuard can support CLIENT-CERT authentication in cunjunction with BASIC, FORM, and DIGEST (not yet implemented). but FORM, BASIC and DIGEST are mutually exclusive.

how to configure multiple schemes?

authentication schemes are configured in the jGuardFilter.xml for web applications, in the markup intitled authScheme. to use multiple scheme, you can use the ',' charcter to divide them.

<authScheme>CLIENT-CERT,FORM</authScheme>

this configuration will try to authenticate the user with its certificate, and if the certificate check fails, it will use the FORM authentication.