New to multiuser apps 1

[lifesupport]

Can someone please suggest a book, article, etc. that will explain how to get started in creating a multi-user application? Thanks

 

[baltman]

http://www.vfug.org/Newsletters/Newsletters2.Afp?!_1T2089NJ4Date=06/01/2004#les

beginner Q regarding multiuser app
thread184-793991

how to convert single user to multiuser
thread184-450283

 

[Elmserv]

I suppose that after working in some banks I have become ultra pessimistic.

I use a semaphore file to control all the locks, this has several advantages.

You can identify who has locked a record/file or procedure

You can lock a complete record/file or procedure

The disadvantage is that it will slow the app down if not used carefully.

Richard

 

[alvechurchdata]

I firmly believe that good data modeling will prevent the need for multiple users to access a single record.

How does good data modelling prevent two practioners wanting to look at the same record?

I'll agree that the situation is far worse with a flat file but even the purest relational model won't prevent two users both wanting to change the phone number of the same patient at the same time.

Geoff Franklin

http://www.alvechurchdata.co.uk

 

[alvechurchdata]

If the patient's phone number(s) are in a separate table (not in the patient's record) there is little chance that two people will need to change that patient's phone number at the same time.

I take your point in practical terms. I quite often see multi-user apps running quite happily without any sort of locking. We're all taught to worry about conflict and to build our apps so that they can be upsized to something massively multi-user. A typical Fox system with perhaps a dozen users sharing a hundred thousand records might run for months without any sort of conflict. It all depends on the patterns of usage and your phone number example is just the sort of data that will stay unchanged for years on end.

Geoff Franklin

http://www.alvechurchdata.co.uk

 

[Elmserv]

I seem to have been critised for my "very" pessimistic locking but one conflict in 6 months one too many in a bank.

We are not talking about changing telephone numbers but automated procedures that access thousands of accounts at a time.

Also I can lock procedures, the code is very simply (about 20 lines)


Richard