Disconnected Application and LoginManager

Just a tip for anyone who would like this sample solution. It has now been included with the Level 300 Advanced Tutorials installed with DevForce. You don't need to email support to get it.

- Heather

Hi David, I am really interested in doing something similar and I wonder if you could email the solution to me as well as we are looking at buying this tool but need to make sure it is suitable.

David,

Thank you for the solution you prepared.

In a not-always-connected application like the one i develop, the user can "Login" disconnected but while the process is alive the communication can be "up" again and she can download "fresh" data (QueryStrategy.DataSourceOnly).

According to the manual if in ibconfig there is true option for LoginManagerRequired, the developer HAS to implement IPersistenceLoginManager to use the Login function. Reading reversely someone gets the meaning: If you do not login you cannot get the data plain and simple.

Using your solution

I logged in using loginmanager
The Users were saved

I changed EmployeeForm_Load to the following:


    private void EmployeeForm_Load(object sender, EventArgs e) {
      mPersMgr = PersistenceManager.DefaultManager;

      mPersMgr.Connect();

      mEmployees = mPersMgr.GetEntities<Employee>();
      this.mEmployeesBS.DataSource = mEmployees;
      this.mManagersBS.DataSource = mEmployees;
    }

Logged in disconnected: Everything OK

While executing mEmployees = mPersMgr.GetEntities<Employee>();
the debugger said:


Failed to login before using PersistenceManager or submitted null credentials.


The only trick i found in order to play disconnected was to replace true with false in the LoginManagerRequired option in ibconfig.

At this point we say good buy to all the theory related to "Secure Server Side User Validation".

After all i think that this is fair:

1. If you want to login disconnected you pay the price
2. If sb logged in disconnected once, has nothing to fear from now on, the list of users and passwords are in the bin file in her disk, so why bother using a LoginManager?

Bottom Line: I wish DevForce had the option to handle disconnected login without failing security considerations. In a BOS deployment scenario this would be unacceptable, so why IdeaBlade says: Use BOS for fully smart client deployment? Of course maybe i miss something.


Thank you for your patience

Andreas

I tried to "borrow the code", but i have declared in ibconfig.config that LoginManager is required (in order to work in the online case). This means that i have to implement it. Every try have failed until now...

Andreas

I would create a PersistenceManager, but I wouldn't use the DefaultManager because the DefaultManager will always try to connect.  Even though your PersistenceManager will be disconnected, you should still be able to read and write to local storage.  (Study the code in the tutorial on "Supported Disconnected Users")

Here is one technique that you might consider.  It requires that the user login and "connect" to a PersistenceManager at least once.  On the initial login, read the necessary tables from the database (e.g., "User", "Roles") and store it to a known location in offline storage.  On a subsequent occasion, if the user is offline, read the necessary tables from offline storage and do the authentication and authorization.