Appeon Server Configuration Guide for J2EE
Advanced configurations related with database connection

You can pre-define in AEM or application server console a certain number of data sources that correspond to different security access levels in the database with different user IDs and passwords. When the user logs in, the application decides which transaction object to data source mapping to use for establishing the database connection.

You should set up an equal number of data sources in AEM or application server console that connect to the database with different privileges, and map the data sources dynamically using the Transaction DBParm property to the PowerBuilder Transaction objects. Transaction object to data source mapping can be dynamically set up or changed by setting or changing the DBMS and DBParm properties of the Transaction object in the application source code. See Dynamic transaction object to data source mapping for the details.

The distributed application technique is supported by Appeon to work around the database security features in a PowerBuilder application. The methodology is to encapsulate the PowerBuilder source code that implements the database securities into NVOs and run them on EAServer. The NVOs may perform actions like creating database connections (manipulation of Transaction object properties), manipulating DataStore objects or executing SQL statements, and transferring the returned information to the Client.

For example, you can encapsulate the user authentication logic into an NVO, and then deploy the NVO to EAServer. In the application source code, you only need to pass the username and the password from the login window to the NVO.

Step 1: Create an NVO and declare a method in the NVO for user authentication. The method compares the user information entered in the application login window with that retrieved from the system table.

The method declared in the NVO:

public function boolean of_checkuser (string 
as_userid, string as_password); 
String ls_DBPass
SELECT fpassword
	INTO :ls_DBPass
	FROM t_user
	WHERE t_user.fuserno = :as_userid;
if sqlca.SQLCode <> 0 Then
	return false
End If
if ls_DBPass <> as_password Then
	return false
End If
	return true
End function

Step 2: Deploy the NVO to EAServer and create a proxy object for the NVO in the Client application.

Step 3: Modify the user authentication logic in the Client application to get the user information from the login window and pass it to the NVO.

The modified script in the Client application:

String ls_User,ls_Pass,ls_DBPass,ls_Err
Long ll_ID
String ls_Mess = 'Please enter a valid user
ID/password.'
If Trim(sle_name.Text) = '' Then
	sle_name.SetFocus()
	MessageBox('Login Not Valid', ls_Mess, exclamation!)
	Return
End if
ls_User = Trim(sle_name.Text)
ls_Pass = Trim(sle_Pass.Text)
If i_logsec.of_checkuser(ls_User,ls_Pass) then
	MessageBox("Infomation","Login successful!")
Else
	MessageBox("Infomation","Login failure!")
End if