Error on Production Orders Add-on when 2 or more users at the same time.

Question

Hi.
Our add-on creates special production orders (SAPbobsCOM.BoProductionOrderTypeEnum.bopotSpecial) with no problem when used by one user, but if there are two or more users  everyone on his own SAPBO session it starts to throw different errors, we think it may be a concurrence problem due to several transactions.
Here a short brief of the code sample and the process:
(error handling and object members not included in the sample)
oDoc.ProductionOrderType = SAPbobsCOM.BoProductionOrderTypeEnum.bopotSpecial
If the oDoc.Add() is correct, We get the last production order created and release it:
Me.sKey = Me.Company.GetNewObjectKey
oDoc = Me.Company.GetBusinessObject(SAPbobsCOM.BoObjectTypes.oProductionOrders)
oDoc.GetByKey(Me.sKey)
oDoc.ProductionOrderStatus = SAPbobsCOM.BoProductionOrderStatusEnum.boposReleased
oDoc.Update()
Then we go for an inventory Entry:
oDoc = Me.Company.GetBusinessObject(SAPbobsCOM.BoObjectTypes.oInventoryGenEntry)
oDoc.DocDate = Date.Now
oDoc.Lines.BaseEntry = Me.sKey
oDoc.Add
And Finally to close the production order:
oDoc.ProductionOrderStatus = SAPbobsCOM.BoProductionOrderStatusEnum.boposClosed
oDoc.Update()
This works fine when only one user is using the add-on, but in the end there wil be at least eight users simultaneously  working with this add-on
The test:
We have four users creating production orders with the  add-on.
Two of them get the usual success messages and the created documents in SAPBO are all correct.
The other two users get diferrent errors messages during the process.
If they wait and try again to run the process it works fine.
Repeating the test get errors on different users depending on which one started the process first.
Our client needs to generate beetwen 900 and 1200 production orders per day, so they can't wait until the process is free for each user to work with it.
The common erros detected are:
Changing the status of the production order:
-5002 - The warehouse is not defined for the item.
-4002 - To generate this document,
           first define the numbering series in the Administration module
-1029 - Field cannot be updated
Adding the production order and inventory entry:
-2038
-1116
-5002
Regards,
Omar Fonseca

Answer 1

The start transaction model didn't Fit well with all the process we are doing, but the idea of locking or holding the other users seems to work pretty fine, we are now using a flag to determine if someone is doing the process and put in hold the new ones.