I'm the same sort of newbie but a self-taught amateur rather than a
student, so take my response with appropriate pinches of salt.
I think it depends on how many simultaneous users/sessions you expect.
You might get away with it by making sure that you only create and close
Connection objects with session scope, but this is the hard way. The
easy way is to use connection pooling; the pool manager creates enough
Connection objects for the application and reuses them as required. Each
Connection object uses resources on the database side of the jdbc bridge
so you don't want to be creating too many of them; before I started
using pooling I found I was getting errors from the db server because my
code was calling DriverManager.getConnection(...) so often that I broke
the server limits on the number of simultaneous connections.
Obviously you don't want different sessions accessing the same open
connection and manipulating the ResultSet - recipe for disaster.
So use connection pooling and your application should scale better.
Apache Commons provide connection pooling packages.
--
Edward Barrow
Copyright Consultant
Copyright and Licensing blog: http://www.copyweb.co.uk/
***Important: see http://www.copyweb.co.uk/space/email for important
information
about the legal status of this email
Graeme McLaren wrote:
> Hi there Richard, thank you for your reply. I'll give the final keyword a
> go. With respect to:
>
>> If this is so, your application is not going to be thread-safe b/c the
>> connection is static and can be used by different threads. If this is
>> for a
>> web application, you should use a connection pool and a datasource
>
> I have been doing a java course and this is my first web app outwith the
> course material (thread safe connections have never been mentioned in the
> course). I don't know anything about connection pools/datasources where
> can
> I find a good tutorial or good newbie info on this?
>
> What problems will be be caused by using the non thread safe connection as
> it is at the moment? I'm thinking performance problems.
>
>
> Thank you again for your reply.
>
> Graeme :)
>
>
>> From: Richard Yee <ryee@(protected)>
>> Reply-To: A mailing list about Java Server Pages specification and
>> reference <JSP-INTEREST@(protected)>
>> To: JSP-INTEREST@(protected)
>> Subject: Re: DB Connection prob
>> Date: Mon, 19 Mar 2007 21:44:14 -0700
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>> Mar 2007 21:44:13 -0700
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>>
>> Graeme,
>> Since you mention that you are using a deployment descriptor, I am
>> assuming this is for a web application. If this is so, your application
>> is not going to be thread-safe b/c the connection is static and can be
>> used by different threads. If this is for a web application, you should
>> use a connection pool and a datasource. In your current problem, your
>> variables should not be final.
>>
>> -Richard
>>
>> Graeme McLaren wrote:
>>> Hi all, I have a prob connecting to my Oracle DB. I have a class called
>>> "DBConnection" and have various setter methods which set values found
>>> in the
>>> deployment descriptor, for example:
>>>
>>> public static void setDriver (String val) {
>>> driver = val;
>>> System.out.println("driver 2= "+driver); // I get the value
>>> displayed here so all is good at this point
>>> }
>>>
>>> I then have a getConnection method within this class:
>>>
>>> public static Connection getConnection(){
>>> try{
>>> Class.forName( driver ); // load the JDBC "driver" class
>>> connection = DriverManager.getConnection( dbURL, username,
>>> password );
>>> // get connection
>>>
>>> /*
>>> more code here
>>> */
>>>
>>> } // end of getConnection
>>>
>>>
>>>
>>> When I try to call getConnection() I get a nullpointerexception at
>>> Class.forName( driver ); as "driver" is set to null, why is this when
>>> the
>>> setter method sets the value?
>>>
>>> All variables are declared set to null and are static so they should
>>> be able
>>> to be set by the setter method shouldn't they? Just thinking about it
>>> now
>>> I'm thinking that when the variables are initialised to "null" that is
>>> them
>>> set and cannot be changed because they are static (and final), would
>>> that be
>>> right?
>>>
>>> How should I fix this?
>>>
>>>
>>> Cheers
>>>
>>> Graeme :)
>>>
>>> ===========================================================================
>>>
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>>>
>>
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