Very Computer

Hello all!

I've implemented a java application, with multi-client server.
the DB is on the server, while many clients can access the database
through the server (each client has a dedicated thread).

The problem is, that I don't know how to prevent lock-downs.
The nature of the work, is that a client gets information from the DB
(through the server), then the person working with the client changes
it a little, and then updates the DB.

The problem starts, when 2 clients need to do this, and the work
needed takes more than a hour to complete. that means that either the
second client needs to wait until the first finishes his update, or
that the second client starts working and then there's the bigger
problem of how and what to save.

As I see it, as long as users need to get information for read-only
purposes, I'm ok. but once a user opens information for
add/update/delete purposes, I cannot let any other user open the same
information for read or write purposes, and further more, if the
information is already opened for read-only, I cannot allow it to be
opened for add/update/delete.

Can this be done through settings in the DB? (I'm using access XP DB).
Or is there another solution already implemented in java or jdbc-odbc?

I thought that transaction would solve this for me, but I don't really
see how.

any thoughts anyone???

Thanks...
Sefi.

Transactions are made for exactly this purpose. I suggest you consult some
appropriate literature on this subject, because a lack of understanding of
related subjects such as locking and isolation levels will cause you
trouble.

Axel Hallez

Sounds like you need a database management system that can support record
level locking - access standalone is not really a great choice for that -
you might try MS SQL Server or another a true RDBMS (or... you can check out
MySQL which is open source and available via download).

Quote:> Hello all!

> I've implemented a java application, with multi-client server.
> the DB is on the server, while many clients can access the database
> through the server (each client has a dedicated thread).

> The problem is, that I don't know how to prevent lock-downs.
> The nature of the work, is that a client gets information from the DB
> (through the server), then the person working with the client changes
> it a little, and then updates the DB.

> The problem starts, when 2 clients need to do this, and the work
> needed takes more than a hour to complete. that means that either the
> second client needs to wait until the first finishes his update, or
> that the second client starts working and then there's the bigger
> problem of how and what to save.

> As I see it, as long as users need to get information for read-only
> purposes, I'm ok. but once a user opens information for
> add/update/delete purposes, I cannot let any other user open the same
> information for read or write purposes, and further more, if the
> information is already opened for read-only, I cannot allow it to be
> opened for add/update/delete.

> Can this be done through settings in the DB? (I'm using access XP DB).
> Or is there another solution already implemented in java or jdbc-odbc?

> I thought that transaction would solve this for me, but I don't really
> see how.

> any thoughts anyone???

> Thanks...
> Sefi.