On 5/17/2011 6:48 PM, Ed Costello wrote:
Hi,
I've been using the Derby Embedded driver in an environment where it
is unsafe to have the JDBC drivers registered with
java.sql.DriverManager (reasons are later in this email). I'm trying
to use the Network Server to make these embedded databases available
to other processes for inspection.
Hi Ed,
I only skimmed at your patch but if I understand it correctly the actual
way you are accessing the Embedded driver are not revealed in the patch
but is implemented via the plugin point you mentioned. I think in
general use DriverManager has been problematic for users and within
Derby and now here is another case. So I think that it might be a better
general approach to file a Jira to remove DriverManager usage from
Network Server to avoid the OSGI conflicts you mention and then just
remove its usage from Network Server all together. I think it is a good
idea to remove all internal DriverManager references if possible. I am
not sure how many there are left after DERBY-4664. This may be the last
one.
Kathey
I've found that the Network Server doesn't work in such an environment
because NetworkServerControlImpl loads the embedded driver from
DriverManager in order to access the actual databases that it is serving.
Would it be acceptable to introduce a plugin point to allow the
Embedded Driver to be loaded in some other fashion? I've attached a
patch which solves this problem for me but would like to know if this
is consistent with the direction of the project?
The reason we can't use DriverManager is that we're running a OSGi /
J2EE hybrid environment where access to databases (and hence the
drivers) are managed by a particular set of services. Having these
drivers registered with the DriverManager breaks the ability to
re-start and re-deploy these bundles cleanly as it can result in
hanging references to the drivers. Because of this the database
management service explicitly clears all Drivers registered with the
DriverManager. There is an OSGi Service which provides equivalent
methods, but the static access provided by DriverManager is
unavailable in this environment.
Thanks in Advance
Ed
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