Casbin RBAC v.s. RBAC96

Casbin RBAC and RBAC96

In this document, we'll compare Casbin RBAC with RBAC96.

Casbin RBAC supports almost all the features of RBAC96, and added new features above that.

RBAC version	Support Level	Description
RBAC0	fully supported	RBAC0 is the basic version of RBAC96. It clarified the relationship between Users, Roles and Permissions.
RBAC1	fully supported	RBAC1 added role hierarchies on RBAC0, meaning if `alice` has `role1`, `role1` has `role2`, then `alice` will also have `role2` and inherit its permissions.
RBAC2	mutually exclusive handling is supported (like this), but quantitative limits are not	RBAC2 added constrains on RBAC0. So RBAC2 can handle mutually exclusions found in policies.
RBAC3	mutually exclusive handling is supported (like this), but quantitative limits are not	RBAC3 is a combination of RBAC1 and RBAC2. RBAC3 supports role hierarchies and constrains in RBAC1 and RBAC2.

In Casbin, the distinction between User and Role is not clear

In Casbin, both the User and the Role are treated as strings. If you wrote a policy file like this:
```
p, admin, book, read
p, alice, book, read
g, amber, admin
```
and call method GetAllSubjects() like this (e is an instance of Casbin Enforcer):
```
e.GetAllSubjects()
```
then you will get the return value below:
```
[admin alice]
```
Because in Casbin, Subjects included Users and Roles.

However, if you call method GetAllRoles() like this:
```
e.GetAllRoles()
```
then you will get the return value below:
```
[admin]
```
And now you know there is a distinction between Users and Roles in Casbin, but is not as sharp as in RBAC96. Of course you can add some prefix to your policies like user::alice, role::admin to clarify their relationships.
Casbin RBAC provides more permissions than RBAC96

Only 7 permissions are defined in RBAC96: read, write, append, execute, credit, debit, inquiry.

However, in Casbin, we treat permissions as strings. This way, you can create some permissions suit you better.
Casbin RBAC supports domains

In Casbin, you can do authorizations by domains. This feature made your Access Control Model more flexible.