Looks like I was able to solve the problem by simply copying the toursDB database directory to a new location. Now App1 and App2 can access the toursDB Cloudscape database with no problem. I discovered that prior to copying the toursDB to a new location the App's were throwing an exception with text that contained something like "can't start database" and ce1.dat in use??
Now that I've copied toursDB to a new location and make connections to that new copy the problem is solved. I guess this must have been due to some sort of file permissions problem on the original database. Thanks for all the comments. I've enclosed the complete description of the problem (not just the question of multiple connections) below for reference.
thanks again,
robert stephens
[EMAIL PROTECTED]
On Nov 24, 2004, at 7:51 PM, Stanley Bradbury wrote:
robert stephens wrote:
I understand that the org.apache.derby.jdbc.EmbeddedDriver does not support simultaneous connections to a Cloudscape database however it appears that even after the Java app that was using the database disconnects and quits. See "Interesting Experiment" in --- 3 --- below.
Problem Example ---------> For example, I can connect to the example "derbyDB" database from App1 and can connecto to the example "toursDB" from App2 but after disconnecting and quiting both App1 and App2.............App2 is never able to start by itself and connect to the "derbyDB" because "once upon a time" App1 had connected to it even though App1 is no longer running.
I'm doing this on MacOS X so there is a possibility that since they (I think) try to share the JavaVM over multiple apps it could be that the Apple JavaVM was still running.
NOTE: See responses by me and others in the Derby User Discussion area
Begin forwarded message:
From: robert stephens <[EMAIL PROTECTED]>
Date: November 24, 2004 5:54:28 PM CST
To: "Derby Discussion" <[email protected]>
Subject: But Why Can't I Connect to toursDB --> Re: Lock on toursDB After App Disconnect Using org.apache.derby.jdbc.EmbeddedDriver
Reply-To: "Derby Discussion" <[email protected]>
ok, but that wasn't my main point - Please read the rest of my posting enclosed again below!! Specifically please have a look at item --- 3 --- and ***** the real interesting part ***** and let me know if you have any comments on what's going on.....................
Problem Example ---------> For example, I can connect to the example "derbyDB" database from App1 and can connecto to the example "toursDB" from App2 but after disconnecting and quiting both App1 and App2.............App2 is never able to start by itself and connect to the "derbyDB" because "once upon a time" App1 had connected to it even though App1 is no longer running.
I'm doing this on MacOS X so there is a possibility that since they (I think) try to share the JavaVM over multiple apps it could be that the Apple JavaVM was still running.
Also note that I am not doing any of this connecting from the command line but always through one of 2 Java/GUI based apps with App1 being DbVisualizer Free 4.1.1. which is a free Java app you can download from http://www.dbvis.com/products/dbvis/index.html and App2 being Sun Java Studio Creator which is downloadable from Sun at http://wwws.sun.com/software/products/jscreator/
However, I did try the following following to make sure all databases and engines were shut down:
--- 1 --- Using DbVisualizer 4.1.1 made a connection (per the Apache/Derby doc) jdbc:derby:;shutdown=true and jdbc:derby:pathTo_toursDB;shutdown=true
--- 2 --- Re-booted MacOS X to make sure no Apple JavaVM was still running
---3 --- Interesting experiment.......using the command line ij tool (java org.apache.derby.tools.ij) I created a new testdb by doing ij> connect 'jdbc:derby:testdb;create=true';
I verified that Sun Java Studio Creator can connect just fine to this newly created Cloudscape database testdb (and it does just fine) - then I quit this application.
I then connected to testdb with DbVisualizer 4.1.1 and it connects to testdb just fine. I then click the DbVisualizer disconnect button and quit the app.
When I start Sun Java Studio again and try to connect to it again I get a "Can't start database" Error message even after doing all the reboot and jdbc:derby:;shutdown=true stuff above
***** the real interesting part ***** prior to connecting to testdb from ANY app if I save a copy of the testdb/log directory, I am able to get Sun Java Studio to connect to testdb if I swap back in the original testdb/log directory and take out the testdb/log directory that was present when the apps each connnected the first time.
I'm thinking there is some info stored in the testdb/log/log1.dat file that isn't getting cleaned up after disconnect somehow and this is making Sun Java Studio Creator think the testdb (or toursDB) is still open (some file is still open) or locked.
On Nov 24, 2004, at 1:46 PM, Daniel John Debrunner wrote:
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robert stephens wrote:
I understand that the org.apache.derby.jdbc.EmbeddedDriver does not
support simultaneous connections to a Cloudscape database
Just to be clear, the embedded driver does support multiple simultaneous
connections from within a single Java virtual machine. Derby supports
multiple users, multiple connections, multiple threads, transactions,
row locking etc.
With the embedded driver the limitation is that only a single Java
virtual machine can connect to the database files. The optional network
server allows multiple connections to the database from multiple java
virtual machines using DB2's JDBC universal driver.
Dan.
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