Re: Interfaces between 2 systems

"Mark" <markg_at_sqrsoftware.co.za> wrote in message news:cmvpn5$3kj$1_at_ctb-nnrp2.saix.net...
> Hi All
>
> There is an interface between my company's database and another company's
> database which is currently causing a great many problems. Database A in
> system A contains a master list of records that have to be sent through to
> Database B in system B. I believe the problem is that only changes to
> records in database A are being sent across to database B as opposed to
all
> records being sent across.
>
> I believe the correct approach is for Database A to publish a view and for
> Database B to pick out any differences in the master list and update /
> delete / insert as necessary (the number of records involved is small and
> does not make this approach prohibitive). The advantages of this approach
vs
> sending only changes include:
>
> 1. If you only send across changes, unless there is an equal starting
point,
> the two databases will never be in equal (unless all records are
eventually
> modified)
> 2. If system A has a bug in sending across changes or system B has a bug
in
> importing these changes, the data will not be synchronized once the bug is
> fixed unless the incorrectly interfaced records are sent through again. If
> all records are interfaced via a view, once the bug in importing /
exporting
> is fixed, the two systems will become synchronized again.
> 3. If only the changes are interfaced, ordering the changes correctly
> becomes very important for the system sending across the changes if there
> are multiple changes to the same record. This can become extremely complex
> if system A (the system sending the changes) is a distributed system and
is
> being updated asynchronously from a variety of sources.
> 4. System B cannot display System A's data to users of system B. This is
> useful for preventing queries because users of system B can see exactly
> where the data is coming from and can contact users of system A to make
the
> relevant corrections to the data if necessary.
>
> There are various other issues that arise from interfacing only changes
> versus interfacing all records but I am having difficulty convincing the
> parties concerned that going to the cost and effort of changing the
> interface is worthwhile and that interfacing all records is a more
"correct"
> approach. Can anyone point me to any relevant research on the prinicples
of
> designing interfaces between two systems that may help me win my case?
> Alternatively, if you believe I am wrong let me know...
>
> Thanks
> Mark
>
>

Look up Replication Received on Thu Nov 11 2004 - 15:32:33 CET