ADO: Error Reading File

[Guest_imported]

I am developing a system where 15 Win 98 clients connect to a Visual Foxpro 6.0 database at NT server 4.0(Service Pack 4) thru VB6 ADO. However, now and then when more than 1 client attempts to read data from the database, the following error reported:
[Microsoft][ODBC Visual FoxPro Driver]Error reading file

In the event viewer from NT server, I also can see these 2 errors:

The browser has received an illegal datagram from the remote computer CBMT2 to name DLDD on ransport NtBT_CpqN. The data is the datagram.

The server received an incorrectly formatted request from \\INDV3. (INDV3 is one of the client computers)

I suspect the following factors:
1. The NT server was not installed/configured properly. Due to the server is incorporated with other party, I cannot simply reinstall the server.
2. Visual Foxpro has bug, however is not found in bug list.
3. Network cabling (although 3rd and 6th wire had been twisted as one pair, and resistance test has been done).

Could anyone help me? Thank you very much for any advice.

lsm

 

[TomasDill]

1. Assure you do not open database in exclusive mode. I doubt about this for ODBC, however, but check this out. To check, just connect from 1 client. Open VFP development environment and try to open this database in VFP as well. When it opened in exclusive mode in ODBS, you will have error like 'Sharing Violation' or something like this.
2. ADO -> VFP not good combination, AFAIK. Too many complains. However, check if you use latest version of ADO. Note that ADO is part of VB6, but it is completely separate set of objects, that may be used without VB6. These are just set of DLL files. You may see version in the date/time of these DLL files, like for most other MS products.
3. Assure you do not have structures in VFP database that are not allowed when using database through ODBC. For example, filters for indexes not supported by ODBC. UDFs in indexes not supported too. Referential integrity in VFP database does not works well through ODBC.
4. There are many limitatioins for SQL statements when working with VFP database through ODBC. I did not seen a list of these limitation, but I suggest you may find it in the technical documentation for VFP Database ODBC driver. Maybe ADO uses one of the not-working methods in certain cases, so causes internal error.

Finally, I wondered about combination VB6 -> ADO - > ODBC - VFP Database. IMHO combination VFP6 -> VFP Database is much more better, reliable and flexible. VFP6 is more powerful programming tool than VB6, MS tells about this.
[sig]<p>Vlad Grynchyshyn<br><a href=mailto:vgryn@softserve.lviv.ua>vgryn@softserve.lviv.ua</a><br>[/sig]