concurrency in local mode

I just found this in someones reply :

>>Programs that access the database are the client threads. Each thread processes a client request (a search or a booking operation).
>>With URLyBird (as with most of the client-server systems), the end-client is the GUI.
>>Of course you can have many clients (many GUI) that want to access the database in local or networked-mode.
>>So you have to make sure that a write operation for a given record at a given time is allowed to one and just one thread.

So as I understood concurrency must be provided in both modes.

But my sun assignment says:
>>Your server must be capable of handling multiple concurrent requests, and as part of this capability, must provide locking functionality as specified in the interface >>provided above. You may assume that at any moment, at most one program is accessing the database file; therefore your locking system only needs to be >>concerned with multiple concurrent clients of your server. Any attempt to lock a resource that is already locked should cause the current thread to give up the CPU, >>consuming no CPU cycles until the desired resource becomes available.

There is nothing about the local mode concurrency, only about servers.
So what do you think I should do ?

Just make sure your Data class can deal with concurrency and you are fine.

Local mode concurrency is really your locking mechanism for your Data class. For example, you need to explicitly call Data's lock method then update/delete then unlock in this order to do any updates/deletes. So say after you sucessfully update the first time, and hang on the second time your locking mechanism is in trouble.

If you can do update/delete in local mode, the network mode is simply allowing multiple threads to access your Data class.