From: Adam 

Paul Ranson wrote:

> So your code has to check the connection before every call?

Depends. No you don't have to. You can simply call to a pooled connection
& it will give you one from it's hashtable of conns when you need it.

It's an architectural issue as you could simply use some form of ORM
instead (e.g. hibernate or JORM). If you want to get ambitious try:

http://c-jdbc.objectweb.org/

It is in C++ too given you have to write a class which instantiates the
conn & then closes/destructs it when the class has been finished with.
Do you keep that class around & if so how does it deal with network/db
errors etc i.e. re-opening dead conns? Do you create the connection
everytime & in a multithreaded/multi-user env do you then run out of db
handles?

Gee it sounds to me like you'd need to arch the solution dependant upon the
use. Gosh that sounds similar....

> How does the
> pool determine that the connection is not active?
>

All sorts of ways. An oft used method is to use a factory method to get a
conn & within the call to get the object from the factory you provide
an expiry time. There can be an upper limit config'ed into the pool by the
server admin i.e. you might set 10 minutes expiry but the server might go
"sod that mate you're getting 18K milliseconds tops".


> Seems like  you're leaping through hoops to avoid doing it the easy way.
>

Hardly. So are you keeping your object around & what happens if the db
refuses/network is down/slow etc.? Having to jump through hoops in
designing your class to guard against such occurences or simply create a
new connection every time you access the db?

Gee seems to me that you should just get a pooling mech as that's the easy way.


> So why does Java not have destructors?

You can (& should) close connections.

> Somebody must be able to say. I think
> it is because the original designers hadn't considered them in any other
> context than memory management. And now they're stuck...
>

Hardly. No reason at all why you can't deference an object & then call
system.gc() or indeed for something like a dbconn you can call
conn.close().


Adam

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