One of the challenging part we found in this integration is the LDAP Users/Groups import. You can connect an LDAP to the Liferay. But, in that case to authenticate users to Liferay against the underlying LDAP it has to import all the users and groups to Liferay's underlying database, which is by default running on Hypersonic.
Since, we only need to keep the user data in a single LDAP, we wanted to avoid this duplication. But, it was not as easy as we thought. If you need to avoid that, then we need to write the complete persistence layer. To understand this better, I guess I need to elaborate more this. Let's take a step back and see how in fact Authentication and Authorization work in Liferay.
Liferay has a chain of authenticators. When you enter your username/password the chain of authenticators will get invoked. This is the place where we plugged in WSO2ISAuthenticator.
The above configuration [which should be in the liferay_home/tomcat/webapps/ROOT/WEB-INF/classes/portal-ext.properties] tells Liferay to load our custom authenticator. Also, the second entry says, once loaded our authenticator, do not invoke rest in the chain. Otherwise, the default Liferay authenticator will also get invoked. Third entry points to the AuthenticationAdmin service running in WSO2 Identity Server.
Now, the username/password go in to WSO2ISAuthenticator and it will talk to WSO2 Identity Server over SOAP to authenticate the user. Once authentication is done, the control once again will be passed in to the Liferay container.
Now is the tricky part. Liferay has it's own permission model - who should be able to see portlets, who should be able to add portlets likewise. For this it needs to find which Liferay roles are attached to the logged in user or which Liferay roles are attached to any group the logged in user belongs to. To get these details it needs to talk to the underlying persistence layer - which will load details from Liferay's underlying database. This is why we wanted to have users imported here from the LDAP.
Even-though it's possible, we decided not to write a persistence layer - but only to override authentication and authorization.
Even in the case of authorization - there are two types. The authorization model governed by Liferay to display/add portlets to the portal. The authorization model used within the Portlet it self to display content within the portlet.
The first type is done by assigning portlet management permissions to a given Liferay role and assigning members [groups/users] to that role from the underlying LDAP. We did not want to do that. Because, that is very much on the portal administration side - and much specific to Liferay. But - the second model - is the one that directly deals with the business functions. That is what we wanted to do in a find-grained manner.
Let's dig more deep in to this...
Even the second model can be done with Liferay's roles and permission. Whenever you want to render something in the portlet that requires some restricted audience, then before rendering that you need to call req.isUserInRole("roleNme"). This is compliant with the JSR too. But the disadvantages are..
1. Our business functionalities in an SOA deployment should not be governed by Liferay roles. Liferay could only be a single channel to access the business functions.
2. We can achieve only the role based access control with this model.
Liferay, also has it's own way of permission checking, within a portlet via PermissionChecker API. You may have a look at this for further details.
Our approach was to write a utility function called hasPermission(). If you extend your portlet from org.wso2.liferay.xacml.connector.SecuredGenericPortlet then this will be automatically available for you. Or else - you can directly call it through AuthzChecker.hasPermission(). These functions are available from org.wso2.liferay.xacml.connector.jar file.
You can copy all jar dependencies from here and copy those to liferay_home/tomcat/lib/ext.
The connection between XACML connector deployed in Liferay and WSO2 XACML engine is through Thrift. You need to add following properties to portal-ext.properties file.
Since by default Identity Server is using a self-signed certificate, either you have import it's public certificate to the trust store of Liferay or set the following two properties in portal-ext.properties file pointing to the Identity Server's key store.
Please note that above configuration is tested with Liferay 6.1.1 and WSO2 Identity 3.2.3/4.0.0.