RMS and midlets

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leggolas - 14 Mar 2005 12:09 GMT

hello.

a student of mine asked this rather interesting questions. he asked
where the db files are stored (im using the Java's Wireless Toolkit
2.1). after all, RMS is said to be persistent so it means, a db file
should be created and saved in the local machine (im using the default
j2me emulator).

second question, are there any restrictions imposed on how large a db
file can be? how about records? im thinking that since its in bytes,
then each record can only grow as much as the data type imposes. am i
correct?

peace~!

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Darryl Pierce - 14 Mar 2005 13:05 GMT

> a student of mine asked this rather interesting questions. he asked
> where the db files are stored (im using the Java's Wireless Toolkit
> 2.1). after all, RMS is said to be persistent so it means, a db file
> should be created and saved in the local machine (im using the default
> j2me emulator).

$WTKDIR/appdb

> second question, are there any restrictions imposed on how large a db
> file can be?

That depends on the device. Devices are required to provide a *minimum*
of 8k, but there are no *maximums* defined in the MIDP specification.
So, OEMs can give as much as they want, but have to provide at *least* 8k.

> how about records?

The number of records is limited by the indexing scheme, which uses an
int. So you can have from 0 to 2,147,483,647 records, assuming there is
sufficient memory to hold them all. :)

> im thinking that since its in bytes,
> then each record can only grow as much as the data type imposes. am i
> correct?

Each record can, as with the store, hold from 0 to 2,147,483,647 bytes
since it's only limit is the way of indexing the elements in the record.

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Darryl L. Pierce <mcpierce@gmail.com>
Visit my homepage: http://mcpierce.multiply.com
"By doubting we come to inquiry, through inquiry truth." - Peter Abelard

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leggolas - 15 Mar 2005 02:23 GMT

thanks darryl. that cleared up a lot of questions. i finally found
the file but interstingly enough, i didnt expect the file to be
prefixed with "run_by_class_storage".

in either case, would i be able to open this with another program which
reads db files (say microsoft access)?

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Darryl Pierce - 21 Mar 2005 02:59 GMT

> thanks darryl. that cleared up a lot of questions. i finally found
> the file but interstingly enough, i didnt expect the file to be
> prefixed with "run_by_class_storage".
>
> in either case, would i be able to open this with another program which
> reads db files (say microsoft access)?

I doubt it, since the file's not a Microsoft Access file. And, that file
is only using whatever format Sun decided upon for the emulator. It's
not necessarily going to be the format used by a real handset.

Signature

Darryl L. Pierce <mcpierce@gmail.com>
Visit my homepage: http://mcpierce.multiply.com
"By doubting we come to inquiry, through inquiry truth." - Peter Abelard

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leggolas - 22 Mar 2005 02:18 GMT

wow! interesting! thanks!

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