Hi Matthew It sounds like comparing a MD5 hash of the CDS file prior to sending and subsequent to receiving the data stream would provide a sufficient check on its integrity.
Todd. > Hi Todd, > > The ClientDatasets initially get populated via a remote server, and it is > this process which in rare cases causes the corruption (e.g. customer on > flakey wireless lan or similar). > > Longterm we will replace this mechanism so the dataset is populated server > side and send back with a hash which will maintain integrity. > > For the moment, we are stuck with a mechanism which populates this cds > data and then writes to file. > > Appending some metadata at this point is a valid option. Ill test and see > if it circumvents the issue. The main issue though is that I'm not sure if > the ClientDataset at this point knows that the data is corrupt, and > therefore we could be exporting a corrupt data chunk packed with some > metadata, which does not help. > > Thats why we really need some protection on load. > > Cheers, > > Matt. > > > > >> Hi Matthew >> >> Are the CDS files being stored as disk files or in a database? How are >> they being corrupted? Faulty back up media? Perhaps you could add some >> meta-data to each file as it is saved. >> >> Todd. >> >>> The driver for the question, is that we have some application client >>> datasets which are put into a defaulted state if a corrupt cds file is >>> loaded. >>> >>> Yes with XML, we can just validate the XML, but we use the binary format >>> so that solution does not apply. >>> >>> At present we basically have two solutions. >>> >>> 1. Load into a test clientdataset as suggested by Alistair. This is a >>> valid solution but does add considerable load time into the startup. >>> >>> 2. Can load into application clientdatasets, and dispose and reload if >>> error encountered. This is ok also but does require additional loading >>> in >>> case of error. >>> >>> What I'm really after is a file level test to check that file should >>> even >>> be attempted. e.g. open file stream seek start and seek end and check a >>> couple of bytes... that type of thing. >>> >>> Matt. >>> >>> >>> >>> >>> >>>> What does "validate" mean for a CDS file ? >>>> >>>> For XML it obviously/intuitively means "is a valid XML representation >>>> of a >>>> CDS file" but for a CDS file, if you dumped it from a client data set >>>> in >>>> the >>>> first place, what additional validation would be needed to ensure that >>>> it >>>> is >>>> a CDS file ? >>>> >>>> >>>> -----Original Message----- >>>> From: delphi-boun...@delphi.org.nz >>>> [mailto:delphi-boun...@delphi.org.nz] >>>> On >>>> Behalf Of Matthew Comb >>>> Sent: Monday, 17 January 2011 10:27 >>>> To: NZ Borland Developers Group - Delphi List >>>> Subject: Re: [DUG] Validating CDS files >>>> >>>> Hey Cam, for space size reasons, we're using the CDS format not the XML >>>> format as the files get pretty large. >>>> >>>> Matt >>>> >>>> >>>> >>>>> If you have dumped the CDS as XML then you can validate it using XSD. >>>>> I >>>>> haven't come across a schema for it but it shouldn't be hard to make. >>>>> >>>>> Cameron Hart | Development Manager | Flow Software Limited >>>>> P: +64 9 476 3569 x910 | M: +64 21 222 3569 | E: >>>>> cameron.h...@flowsoftware.co.nz >>>>> PO Box 305-237, Triton Plaza, Auckland 0757, New Zealand | >>>>> www.flowsoftware.co.nz >>>>> >>>>> This message is intended for the addressee named above. It may contain >>>>> privileged or confidential information. If you are not the intended >>>>> recipient of this message you must not use, copy, distribute or >>>>> disclose >>>>> it to anyone. >>>>> >>>>> Please consider the environment before printing this email >>>>> >>>>> -----Original Message----- >>>>> From: delphi-boun...@delphi.org.nz >>>>> [mailto:delphi-boun...@delphi.org.nz] >>>>> On Behalf Of Matthew Comb >>>>> Sent: Monday, 17 January 2011 10:03 a.m. >>>>> To: NZ Borland Developers Group - Delphi List >>>>> Cc: NZ Borland Developers Group - Delphi List >>>>> Subject: [DUG] Validating CDS files >>>>> >>>>> Does anyone know if there is a way to Validate a CDS file (midas) >>>>> before >>>>> attempting to load it into the dataset ? >>>>> >>>>> Matt >>>>> >>>>> _______________________________________________ >>>>> 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 >>>>> >>>>> _______________________________________________ >>>>> 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 >>>>> >>>>> >>>>> >>>> _______________________________________________ >>>> 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 >>>> >>>> _______________________________________________ >>>> 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 >>>> >>>> >>>> >>> _______________________________________________ >>> 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 >>> >>> >> _______________________________________________ >> 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 >> >> > > _______________________________________________ > 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 > _______________________________________________ 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
