Reusable class - user access control

This is another important area in the systems and it is reusable as long as the design is generic to cover all possible combination.

Basically, it should meet the following requirements:

• Security control - allows user to logon to the system and verify their user name and password.
• Access permission - permission could be controlled by menu level, screen level and field level (whether the field is show/hidden or enable/disable).
• User access log - this is compulsory for audit purpose and also the alert.
• Access deny alert - upon hitting certain number of invalid user name or password, the system should generate alert and email it to the system administrator.
• Password policy - you may consider to implement minimum password length and password complexity.
• Allow supervisor overriding - this can be useful when the current user does not have permission to access certain feature (such as edit customer address) but requires to do so.
• In case the system is a web base system, it should store the browser type and visitor IP address for audit purpose.

 You need the following classes to support the above mentioned requirements:

1. CUser - this class stores the user information such as user name, password, email address, etc.
2. CAction - this class stores all the permissions (or features) for the system.
3. CUserAccessLog - this class responsible for keeping track the user login and logout activities.
4. CLog - this class (which has been discussed in previous article) which is responsible for storing the audit information such as which "action" (or "featuer") the user has clicked.

For the detailed implementation, you might have work it out by yourself.