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kingsley143 7th December 2017 04:48

Difference between DAL and UE

I am new to LN, I want to know the difference between DAL, DAL2 and UE in LN.
In which case we use DAL,DAL2/UE. Please help.

Thanks in advance.

jeffersyuan 26th December 2017 03:09


To be simply, DAL and DAL2 means, you can use it for your own table.
However, the UE means, you do not have the source code, you can do some extends.


bdittmar 9th January 2018 14:06

UE UserExit


A User Exit DLL (UEDLL) is a DLL that will reside outside the standard software.
It will have the same name as a standard DAL with the extension ‘ue’ (for ‘user exit’).
E.g. ‘whinh200ue’ for table whinh200. Customers can implement a UEDLL in order
to be able to define extra business logic before and after
the standard ‘before’ and ‘after’ handling of

saves and deletes, by means of specific hooks that will be executed by the 4GL engine
and/or DAL Engine. In this way it is possible to e.g. conditionally publish
data changes to the outside world.

Interaction with 4GL Engine / DAL Engine

When present, the User Exit DLL for a certain table will be loaded by the 4GL engine/DAL
Engine by the time the DALfor this particular table will be loaded. In situations where
no DAL is present this will be the moment at which a DAL would be loaded if it existed.
This means that there is no need to have a DAL in order to make use of the UEDLL.


A DLL becomes a UEDLL when it meets the following conditions:
•Its name is consisting of the table code with ‘ue’ as suffix, like whinh200ue
•It includes bic_dal, as follows: #include <bic_dal>


A UEDLL is treated like a regular DAL. This means all kind of DAL related functionality can be used, like:
•Pre-defined variable subdal

Note however that the following restrictions apply:
•Business methods cannot be implemented in a UEDLL Instead the business logic
should be programmed in another (separate) general DLL.
•It is strongly discouraged to define other external functions in a UEDLL and
link the UEDLL directly to other scripts. Instead, use a normal general DLL.
(This also applies to regular DALs).

User Exit Hooks

A UEDLL script can contain the following hooks:



Ajesh 17th January 2018 11:10

No Difference in their hooks only User exit Hooks gets called before or after DAL Hooks depending on the UE Hook which is being called.

For example, gets called before and gets called after

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