How do you deal with this issue?

I have a issue here: If an user is on a order, another user is not allowed to issue an invoice on this order.

What I am doing is: when an user open a order, I add a record to the usage table, when he leave the order, I delete this record. when exception happened I will also delete this recode.

The problem is: in some case, the user is not there, but the recorde is not deleted. I guess there are many possibilities the record is not deleted, for example, when the user is on the order, the power is failure, or some other unkonwn reasons.

How do you deal with this issue? Use transaction? Is there any other problems?

Message forwarded from pcsoft.us.windev

Hi,
Maybe you point to wrong record number for deletion.
If you use Hseek or HreadSeek try to do nect:

nActualRecord is int = HRecNum(MyTable)

//Your code here and when it is finished

HRead(MyTable, nActualRecord)
HDelete(MyTable)

Hi Jenny,

You could automatically delete all log entries from a certain age, e.g. 30 minutes.
If someone is on an order for a longer period the log entry will have to be renewed.
More simple is just use Windev's locking mechanism.

Regards,
Piet

Hello Jenny

An alternative method might be to write the current user id into the order header record. You would then know who has the order open and when they close the order header record you could easily clear their info out. This would be quicker and simpler than maintaining a separate usage file

Regards
Al

My 2 euros worth... building on Piet's answer:

Have the application wants to read and work with the order check the control record for a previous "lock" on the order, and if none found create a record in the control file like you are doing, except write the computers unique ID, the order ID and the date/time the app read the order record. Every x time frame (whatever works for you) have the application rewrite the control record with an updated time.

If a second computer wants to create an invoice (or work with the same order), have it check the date/time in the control records (check all records if an invoice is to be created, check one for the unique order ID if you only want to work on that specific order) (as you can see there can be multiple orders "locked" at any one time). If the check is within y amount of time then restrict the application from creating an invoice or working with that "locked" order (where y is at least greater than 2 times x's value - just in case the first computer misses an update due to communications issue or something else). If it is over y time, change the control record to the second computer's unique ID and time (taking ownership of the order(s)), and allow creation of the invoice/modification of the order.

The first computer that read the order in for modification, before being allowed to save the modified order record, has to check that the control record (for the appropriate order ID) for it's own unique computer ID. If it's not there (was deleted) or there is another computer's ID (someone took ownership), inform the user and don't allow any writes from the first computer.

This way there is no automatic deletion of the control record if no other application needs to access that order or create invoices on that/those orders.

Issues:

1. Time, making sure the clocks are synced between the applications.

2. The user gets up and walks away from the original order. I would code it so that if there is no keyboard, mouse or other use (the user is in Outlook, or some other computer usage that would indicate the user is still at the computer and has not abandoned the order), the program times the user out, releases the order with no modifications, deletes the control record so others can create invoices or work with the order.

This was just off the top of my head, if anybody sees any issues let's post them and work the thought through.

Art