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Posted to users@tomcat.apache.org by Natasha N Wright <nn...@Cs.Nott.AC.UK> on 2007/03/16 11:07:55 UTC
Servlet Caching
Hi,
I have a servlet which connects to a database; once the connection is
made I pass a connection object into another class which uses this
object to execute queries on the database.
When i run the servlet my queries are executed fine, when i try to run
the application for a second time my class executing the queries doesn't
work - it appears that it doesnt recieve the connection object properly
it bombs out at the stage
stmt = conn.createStatement();
I am creating a connention within the inint() method of my servlet.
When i re-start tomcat everything works fine again - this leads me to
believe hat i have connection caching issuse.
I have set the context param in server.xml to reloadable = true (not
sure if this makes any difference)
I am also not using a connection pool to connect to my database.
I am using tomcat v.4.0 with Java 1.4
Any advice is appreciated
Cheers
Natasha
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Re: Servlet Caching
Posted by Pid <p...@pidster.com>.
Tim Lucia wrote:
>
>> -----Original Message-----
>> From: Natasha N Wright [mailto:nnw03u@Cs.Nott.AC.UK]
>> Sent: Friday, March 16, 2007 6:08 AM
>> To: Tomcat Users List
>> Subject: Servlet Caching
>>
>> Hi,
>>
>> I have a servlet which connects to a database; once the connection is
>> made I pass a connection object into another class which uses this
>> object to execute queries on the database.
>> When i run the servlet my queries are executed fine, when i try to run
>> the application for a second time my class executing the queries doesn't
>> work - it appears that it doesnt recieve the connection object properly
>> it bombs out at the stage
>> stmt = conn.createStatement();
>
> What exception are you getting? Connection closed? Odds are very good you
> closed the connection somewhere. Per the servlet spec, init() is called
> once when the servlet is initialized. It is generally a bad idea to use a
> single connection in a servlet as all threads running in that instance will
> be forced to use that connection, which leads to synchronization issues. It
> is far better to have a connection per request, allocated from a connection
> pool.
...which is dead easy to configure via JNDI
http://tomcat.apache.org/tomcat-4.1-doc/jndi-datasource-examples-howto.html
I think we'd all recommend pretty strongly that you upgrade your version
of Tomcat to something newer if you can. If you're stuck with Java 1.4,
then go for 5.0.latest (4.0 is oooolllldddd, 4.1.n is better).
If you can install Java 1.5+ and go for 5.5 or 6.0 then all the better.
The J1.5+ TC5.5+ combo is faster, better...
> Tim
>
>> I am creating a connention within the inint() method of my servlet.
>> When i re-start tomcat everything works fine again - this leads me to
>> believe hat i have connection caching issuse.
>> I have set the context param in server.xml to reloadable = true (not
>> sure if this makes any difference)
>> I am also not using a connection pool to connect to my database.
>>
>> I am using tomcat v.4.0 with Java 1.4
>>
>> Any advice is appreciated
>>
>> Cheers
>>
>> Natasha
>>
>> This message has been checked for viruses but the contents of an
>> attachment
>> may still contain software viruses, which could damage your computer
>> system:
>> you are advised to perform your own checks. Email communications with the
>> University of Nottingham may be monitored as permitted by UK legislation.
>>
>>
>> ---------------------------------------------------------------------
>> To start a new topic, e-mail: users@tomcat.apache.org
>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
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>
>
>
>
>
> ---------------------------------------------------------------------
> To start a new topic, e-mail: users@tomcat.apache.org
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>
>
RE: Servlet Caching
Posted by Tim Lucia <ti...@yahoo.com>.
> -----Original Message-----
> From: Natasha N Wright [mailto:nnw03u@Cs.Nott.AC.UK]
> Sent: Friday, March 16, 2007 6:08 AM
> To: Tomcat Users List
> Subject: Servlet Caching
>
> Hi,
>
> I have a servlet which connects to a database; once the connection is
> made I pass a connection object into another class which uses this
> object to execute queries on the database.
> When i run the servlet my queries are executed fine, when i try to run
> the application for a second time my class executing the queries doesn't
> work - it appears that it doesnt recieve the connection object properly
> it bombs out at the stage
> stmt = conn.createStatement();
What exception are you getting? Connection closed? Odds are very good you
closed the connection somewhere. Per the servlet spec, init() is called
once when the servlet is initialized. It is generally a bad idea to use a
single connection in a servlet as all threads running in that instance will
be forced to use that connection, which leads to synchronization issues. It
is far better to have a connection per request, allocated from a connection
pool.
Tim
> I am creating a connention within the inint() method of my servlet.
> When i re-start tomcat everything works fine again - this leads me to
> believe hat i have connection caching issuse.
> I have set the context param in server.xml to reloadable = true (not
> sure if this makes any difference)
> I am also not using a connection pool to connect to my database.
>
> I am using tomcat v.4.0 with Java 1.4
>
> Any advice is appreciated
>
> Cheers
>
> Natasha
>
> This message has been checked for viruses but the contents of an
> attachment
> may still contain software viruses, which could damage your computer
> system:
> you are advised to perform your own checks. Email communications with the
> University of Nottingham may be monitored as permitted by UK legislation.
>
>
> ---------------------------------------------------------------------
> To start a new topic, e-mail: users@tomcat.apache.org
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
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