[Zope-DB] Re: Auto-reconnect in DCOracle2

Matthew T. Kromer matt at zope.com
Wed Sep 24 11:26:17 EDT 2003

The DA is only going to know that the connection closed if it gets an 
error sending a command :(

The DA's query method has a lot of try/except wrappers to try to boost 
it around the connection dissapearing and then causing a reconnect to 
take place.

Chris Withers wrote:

> Christian Theune wrote:
>>>> On this last point, has anyone implemented something like an 
>>>> 'auto-reconnect' feature for DCOracle 2 so that the user never sees 
>>>> the DCOracle2 Error: (1012, 'ORA-01012: not logged on') message?
>>> Hmmm, I'm guessing ZSQL methods call the DA/Connection object to get 
>>> the database connection? Is there anything that can be done in 
>>> Shared.DC.ZRDB.Connection.Connection.__call__ to do this 
>>> re-connection if the connection is found to be disconnected?
>>> What would be the best way to find out if the connection is 
>>> disconnected?
>> Only the python database module can know that for sure. 
> And how would it know?
>> Actually the
>> ZRDB API doesn't require anything to be Python DB API compliant, so you
>> can't count on that. Most DAs use _v_connected != None to indicate they
>> (not the python modules) have a connection.
> Indeed, but this doesn't actually tell me whether the connection works 
> or not.
> In this thread, the _v_connected will be not None, but the Oracle 
> connection has gone away and so the user sees unsightly error messages 
> when a ZSQL method tries to use the connection.
> What I'm after is code that will cause the connection to silently 
> re-connect if this happens.
> Anyone got any ideas?
> cheers,
> Chris

Matt Kromer
Zope Corporation  http://www.zope.com/ 

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