Matthew wrote: > I wasn't suggesting that wireless was changing byte > structure, but if you are streaming data, and your datastream > gets disconnected, then you could end up with an incomplete transfer. > > I'm not 100% sure that midas catches all scenarios when > working off a remote data instance ? > > Note we use dbx4mysql + midas. > > Note also that I cannot rule out the drivers either and also > could be the data out of the db server, its a tricky one to > track down, as you basically have a black box from db -> > dbxmysql + midas... > > What I do know is that its very rare. e.g. maybe 1 in 10,000 > usages corrupts the file and has occurred in more than 1 > location, so it does not appear to be station specific. > > Logically with these stats, I can only put that down to a > flakey connection, otherwise the error rate would be more often.
If you can't go the hash route in the short term, it sounds to me like you'll need to reverse engineer the cds format to determine whether there is a examinable file tail. I don't imagine the format will be _that_ hard to reverse engineer but then I've done a fair bit of binary reverse engineering so maybe I'm being a bit cavalier. If you make a number of simple and small cds files and compare and contrast them, you can probably work your way up in determining the encoding. Assuming it was implemented using some form of streaming class model, there may well be a common interface and then a cds outputter and an xml outputter. If so, there is probably going to be a fairly 1-to-1 mapping between the binary format and the xml format in terms of logical schema. These xml inspited compressed binary schemas are often all pretty similar - they replace the text tags and attributes with binary tokens taken from a dictionary to avoid repetition and reduce the size. As an side, often you're better off just zipping the xml rather than implementing and debugging your own tokenized 'binary xml' engine but that's a whole different argument :-) Anyway, you might get lucky and quickly determine there is a common metadata trailer or end of data stream signature in the binary schema, similar to how zip files replicate their metadata directory and place it at the end of the file. This may seem overkill for your current problem since you're aiming for a short term solution, but having a cds stream viewer which can load into a virtual tree view might be a useful in-house debugging tool down the track. Cheers, Paul. _______________________________________________ NZ Borland Developers Group - Delphi mailing list Post: delphi@delphi.org.nz Admin: http://delphi.org.nz/mailman/listinfo/delphi Unsubscribe: send an email to delphi-requ...@delphi.org.nz with Subject: unsubscribe
