[security-dev] IdentityManager API review

[Shane Bryzak]

Hey guys,

I spent some time reviewing the IdentityManager API today to identify 
any redundancies and also locate any holes where we might not properly 
support required features, as well as a general "sanity" check to ensure 
that what we're exposing via this API makes sense and is intuitive for 
consumers.  As Anil has pointed out already, our short term priority for 
the project is to stabilize the API - this is extremely important as 
PicketLink will provide the security foundation for many other 
projects.  With that in mind I'd like to strongly encourage everyone 
with a stake in this to carefully review the API and provide feedback, 
as once we release it it will be essentially set in stone.

To try and avoid a wall of text (and make this post easier to reply to), 
I'm going to break this post up into sub-sections, one for each feature 
group.  For each section, I'll include the API as it currently exists, 
followed by a brief summary of my thoughts and any recommendations I may 
have - this is especially where I want to hear any feedback indicating 
whether you agree or disagree with my assessment.  Let's start with the 
user-related methods:

User management
-------------------------

     User createUser(String name);

     void createUser(User user);

     void removeUser(User user);

     void removeUser(String name);

     User getUser(String name);

My thoughts:

1. I'm wondering if we should remove the createUser(String) method and 
just have createUser(User).  This would make sense in a way because I 
can't think of many use cases where you might want to create a User with 
just a username and not any of the other typical information (such as 
first name, last name, e-mail address, etc). Creating a User via 
createUser(String) when you actually want to set the other details after 
the initial User creation is also horribly inefficient, requiring 
multiple round trips to the database (or whatever identity store backend 
you use).  To add to that, the actual parameter name is a little 
unintuitive - "name" could refer to any number of things - is it the 
username or the user's actual name that you need to provide here?  My +1 
goes to removing createUser(String).

2. Similar to point 1), having two removeUser() methods seems equally 
redundant.  The User object that needs to be provided to the 
removeUser(User) method can be easily looked up by calling getUser(), as 
per this example:

identityManager.removeUser(identityManager.getUser("jsmith"));

3. As I also pointed out in point 1), the "name" parameter is a little 
unintuitive.  In regard to the getUser() method I think we should rename 
the "name" parameter to "username" just so it's perfectly clear what the 
method expects.

4. We don't currently have any way to update User details.  I recommend 
that we add an updateUser() method as follows:

void updateUser(User user);

This will allow User details such as their first and last name, e-mail 
address etc to be updated without having to delete and re-create the 
User.  Extending on this a little further, I'm wondering if we should 
think about adding an audit API that logs these changes.  Perhaps it's 
something to think about for a later release.

Group management
--------------------------

     Group createGroup(String id);

     Group createGroup(String id, Group parent);

     Group createGroup(String id, String parent);

     void removeGroup(Group group);

     void removeGroup(String groupId);

     Group getGroup(String groupId);

     Group getGroup(String groupId, Group parent);

     void addToGroup(IdentityType identityType, Group group);

     void removeFromGroup(IdentityType identityType, Group group);

My thoughts:

1. I think there is a little bit of ambiguity here in regard to the 
differences between a Group's ID and name.  To assist in understanding 
the differences, here's the JavaDoc pasted from the Group interface:

     /**
      * Groups are stored in tree hierarchy and therefore ID represents 
a path. ID string always begins with "/" element that
      * represents root of the tree
      * <p/>
      * Example: Valid IDs are "/acme/departments/marketing", 
"/security/administrator" or "/administrator". Where "acme",
      * "departments", "marketing", "security" and "administrator" are 
group names.
      *
      * @return Group Id in String representation.
      */
     String getId();

     /**
      * Group name is unique identifier in specific group tree branch. 
For example group with id "/acme/departments/marketing"
      * will have name "marketing" and parent group of id 
"/acme/departments"
      *
      * @return name
      */
     String getName();

Taking the above JavaDoc into account, it seems that where we are 
specifying "id" as a method parameter we should be specifying "name" 
instead.  If we are indeed providing a "fully qualified" path to the 
createGroup() method, then there is no need to also specify the parent 
as it can be easily derived from the path.  More on this in the 
following points.

2. We currently have three createGroup() methods for creating a new 
Group.  I think we should remove the (String, String) variant, as the 
parent parameter is ambiguous (is it the parent's ID or name we need to 
specify here?), and rename the "id" parameter of the (String, Group) 
variant to "name", leaving us with the following:

     Group createGroup(String id);

     Group createGroup(String name, Group parent);

This then gives us two ways of creating a group.  We can either specify 
the fully qualified group ID:

Group employees = identityManager.createGroup("/employees");

Or we can specify a subgroup name and parent Group:

Group managers = identityManager.createGroup("managers", employees);

We can also use this second form to create a "root" group by just 
specifying null for the parent:

Group admins = identityManager.createGroup("admins", null);

3. For the removeGroup() methods, I think what we have is fine.

4. For the getGroup() methods, I'm happy with the first one (String 
groupId) but I think the second one (String groupId, Group parent) needs 
to be (String name, Group parent) instead.  The first method would be 
used when the fully qualified group ID is known, and the second one 
would be used when you already have the parent Group and know the name 
of the subgroup.

5. The addToGroup() and removeFromGroup() methods seem fine to me.

6. One thing we don't have is a method to test whether an IdentityType 
is a member of a Group.  I suggest we add another method to support this:

boolean inGroup(IdentityType identityType, Group group);

Roles
----------

     Role createRole(String name);

     void removeRole(Role role);

     void removeRole(String name);

     Role getRole(String name);

     boolean hasRole(Role role, IdentityType identityType, Group group);

     void grantRole(Role role, IdentityType identityType, Group group);

     void revokeRole(Role role, IdentityType identityType, Group group);

My thoughts:

1. I would remove the removeRole(String) method as the same thing can be 
achieved with removeRole(getRole(String)).

2. I would swap the order of the Role and IdentityType parameters within 
the hasRole(), grantRole() and revokeRole() methods.  As the 
IdentityType is the primary artifact in these operations it makes sense 
to have it listed first.

3. We don't have any explicit support for application roles, which are 
roles where there is no Group component (for example, an 
application-wide "admin" role).  We could support this by just allowing 
hasRole(), grantRole() etc to accept null values for the Group 
parameter, however I feel it would be more semantically correct to 
provide a distinct set of methods for the purpose of supporting 
application roles, as follows:

     boolean hasApplicationRole(IdentityType identityType, Role role);

     void grantApplicationRole(IdentityType identityType, Role role);

     void revokeApplicationRole(IdentityType identityType, Role role);


Query API
--------------

     <T extends IdentityType> IdentityQuery<T> createQuery();

My thoughts:

1. After our recent rewrite of the Query API I'm satisfied with what we 
have now.

Credential management
-------------------------------

     boolean validateCredential(User user, Credential credential);

     void updateCredential(User user, Credential credential);

My thoughts:

1. I'm satisfied with what we currently have, however we still need to 
review the mechanism that we provide for encoding passwords.  I'm not 
sure that it will have any effect on these methods though (I'm toying 
with the idea of integrating the password encoding functionality via the 
IdentityStoreInvocationContext).

Identity expiry
------------------

     void setEnabled(IdentityType identityType, boolean enabled);

     void setExpirationDate(IdentityType identityType, Date expirationDate);

My thoughts:

1. I think these methods are fine the way they are.  One discrepancy 
that I've identified is that a User can be created already being 
disabled or having an expiry date, while for a Role or Group the 
equivalent status must be set via these methods after creation.  I'm not 
sure this is a big deal though.

Attributes
-------------

     void setAttribute(IdentityType identityType, String attributeName, 
String attributeValue);

     String getAttribute(IdentityType identityType, String attributeName);

My thoughts:

1. This area poses a slight dilemma.  Currently the API only supports 
simple String-based attribute values, however I'm pretty sure that 
people are going to want to store all sorts of things, ranging from 
boolean and Date values through to large byte arrays that store a User's 
photograph or other data.  If everyone is in agreement that we need to 
support more than just String values, then the first thing we probably 
need to do is modify these methods to work with a Serializable instead.

2. If we all agree on point 1), the next thing we need to decide is 
whether we want the capability to make some attribute values "lazy 
loaded".  If we want to do a quick lookup of a User object for the 
express purpose of assigning a Role or Group membership (or any other 
type of simple operation) then we probably don't want the performance 
hit of having to load bulky attribute data.

3. With the above two points in mind, I'm going to hold off on surmising 
any further on attributes until some of you guys weigh in with your 
opinions.  I do have some rough ideas, however I'll wait until we have a 
consensus of exactly what we want to achieve here before we proceed further.

Utility methods
--------------------

     IdentityType lookupIdentityByKey(String key);

My thoughts:

1. This method is required by other features, such as the Permissions 
API.  I'm fine with what we have here.

In summary
----------------

I apologise for yet another epic e-mail to the list, however this is 
everyone's chance to review the API for themselves and decide whether or 
not it will be suitable for addressing all of your requirements.  I'd 
like to get this API stable by next week so please don't be shy about 
speaking up.  I'm especially looking forward to hearing your opinions 
about how we handle attributes (there may even be some relevant JSR-351 
stuff that we should be looking at here).

Thanks,
Shane