Hi Sebastian,
With SQL Server I use something like follows:
<jdbc-connection-descriptor ... >
<connection-pool
maxActive="10"
testOnBorrow="true"
testOnReturn="false"
testWhileIdle="true"
timeBetweenEvictionRunsMillis="10000"
minEvictableIdleTimeMillis="20000"
numTestsPerEvictionRun="10"
validationQuery="SELECT 1" />
<sequence-manager>
...
</jdbc-connection-descriptor>
The key is to specify a fast, simple query so as to not suffer a great
performance penalty.
Wally
-----Original Message-----
From: news [mailto:[EMAIL PROTECTED] On Behalf Of Sebastian
Sent: Monday, May 03, 2004 11:05 AM
To: [EMAIL PROTECTED]
Subject: Re: How to test db connection on application startup
How would a generic ValidationQuery look then, that simply reviews,
whether with a certain DB instance can be established communication?
Gelhar, Wallace Joseph wrote:
> Hi Sebastian,
>
> I think it would be wiser to specify a validation query in the
> database repository descriptor to check if the connection is valid
> *each* time it is used. This will deal with not only the database
> being unavailable at startup, but throughout the operation of the
> application.
>
> BTW, I suspect that the service method did nothing because your code
> did nothing that required opening a connection (i.e. opening a broker
> does not open a connection until it is needed). Also note that
> Brokers are pooled separately from Connections.
>
> Wally
>
> -----Original Message-----
> From: news [mailto:[EMAIL PROTECTED] On Behalf Of Sebastian
> Sent: Monday, May 03, 2004 10:31 AM
> To: [EMAIL PROTECTED]
> Subject: Re: How to test db connection on application startup
>
>
> I changed the code to obtain the connection from the
> serviceConnectionManager, but the problem remains, I can't catch the
> thrown java.sql.SQLException. Any ideas?
>
> try
> {
> pb = PersistenceBrokerFactory.defaultPersistenceBroker();
> pb.serviceConnectionManager().getConnection();
> }
> catch (Exception e)
> {
> throw new DatabaseOpenException(e);
> }
>
> Sebastian wrote:
>
>
>>Hi,
>>
>>when launching my ojb app I'd like to test if the db connection is
>>available. I thought I can do something like this:
>>
>>try
>>{
>> pb = PersistenceBrokerFactory.defaultPersistenceBroker();
>> pb.beginTransaction();
>> pb.commitTransaction();
>>}
>>catch (Exception e)
>>{
>> throw new DatabaseOpenException(e);
>>}
>>
>>When launching the app with turned off db I get exception stacktrace
>>appended to the end of this post, but the SQLException is actually not
>
>
>>catched by my catch block. I guess that is because opening the db
>>connection is done in a separate thread?
>>
>>My question is, what is the best generic way to test the db connection
>>when launching an ojb enabled app?
>>
>>java.sql.SQLException: Unable to connect to any hosts due to
>>exception:
>>java.net.ConnectException: Connection refused: connect
>> at com.mysql.jdbc.Connection.createNewIO(Connection.java:1797)
>> at com.mysql.jdbc.Connection.<init>(Connection.java:562)
>> at
>>
>
> com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:
> 36
> 1)
>
>> at java.sql.DriverManager.getConnection(Unknown Source)
>> at java.sql.DriverManager.getConnection(Unknown Source)
>> at
>>
>
> org.apache.ojb.broker.accesslayer.ConnectionFactoryAbstractImpl.newCon
> ne
> ctionFromDriverManager(Unknown
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.accesslayer.ConnectionFactoryPooledImpl$ConPoolF
> ac
> tory.makeObject(Unknown
>
>>Source)
>> at
>>
>
> org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObj
> ec
> tPool.java:816)
>
>> at
>>
>
> org.apache.ojb.broker.accesslayer.ConnectionFactoryPooledImpl.getConne
> ct
> ionFromPool(Unknown
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.accesslayer.ConnectionFactoryAbstractImpl.lookup
> Co
> nnection(Unknown
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.accesslayer.ConnectionManagerImpl.getConnection(
> Un
> known
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.accesslayer.ConnectionManagerImpl.localBegin(Unk
> no
> wn
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.core.PersistenceBrokerImpl.beginTransaction(Unkn
> ow
> n
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.core.DelegatingPersistenceBroker.beginTransactio
> n(
> Unknown
>
>>Source)
>> at
>>
>
> org.apache.ojb.broker.core.DelegatingPersistenceBroker.beginTransactio
> n(
> Unknown
>
>>Source)
>> at test.DBTest.<init>(DBTest.java:26)
>
>
>
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