Hi I am putting together a functional specification in preparation for
writing a VB Dot Net upgrade an existing Access (VBA) and VB system.
It is currently a tiered system with an IBM AS400 providing a DB2 Database.
There are 5 or 6 of sites and each site has 2 to 6 PCs (involved in this
system). One PC on each site acts as an application server and sub database
server, ie it is an MS Access Application that is scheduled to run approx
every hour and when it runs, it downloads several files from the AS400 and
deletes old records, updates existing records and appends new records into
and Access MDB database file. It then downloads certain data to Access files
on the other PCs on the site. Each PC must be capable of operating even when
the local site server is unavailable so each PC has its own database.
The site server is required because when the PCs process records, a copy of
the record is saved in the Site server database and some transactions
require access to previously saved records (possibly from a different PC).
Also some of the processing to and from the AS400 is not fast and rather
than letting every PC call for a download of data each hour we are using the
site servers to disseminate the data.
OK you can see it is fairly complex and it is even more so at the PC level.
We are hoping to simplify some of this by replacing the access databases at
PC level with DataSets and XML files.
My question refers to structure at the server level. Initially I thought
that I should retain the Access MDB file at the site server to accomadate
the multiple PCs writing records to it and using the Jet Engine to take care
of record locking (there should not be much chance of record being changed
by more than one PC).
This morning I was thinking that possibly this could all be achieved with
DataSets and XML? Could the AS400 downloaded data be held in an XML file and
when new records are posted the XML file is re-written? I know it could but
how do I handle multiple PCs that may try to write records simultaneously?
Am I better sticking with Access MDB at this level?
Thanks for any advice.
Doug
The other