Synchronize DataSource Instance?

[kavin clain]

After configuring web.xml & context.xml I am using below code to get Connection. "DBBoard.getConnection()"

Do I need to synchronize on DataSource instance... ?

    
public class DBBoard {
	
	static DataSource dtsrc;
	static Context envCtx;

	public static Connection getConnection(){
		Connection con = null;
		if(dtsrc==null){
			getDataSource();
		}
		try{
			con = dtsrc.getConnection();
		}catch(SQLException es){			
			es.printStackTrace();
		}
		
		return con;
	}

	public static void getDataSource(){
		if(envCtx==null){
			getEnvironmentContext();
		}
		try{			
			dtsrc = (DataSource) envCtx.lookup("jdbc/someDB");
		}catch(NamingException ne){			
			ne.printStackTrace();
		}		
	}

	public static void getEnvironmentContext(){
		try{
			envCtx = (Context) new InitialContext().lookup("java:comp/env");
		}catch(NamingException ne){			
			ne.printStackTrace();
		}		
	}
}

[Peter Johnson]

Is there a reason why you wrote this instead of making use of the database connection pool? Using the pool is the best thing to do within a Java EE app.

[Deepak Bala]

Most containers provide their own connection pool. Tomcat for example can use commons DBCP to manage connections. Which container do you use and why dont you try to use its connection pooling mechanism ?

[kavin clain]

I am using Tomcat 5.5. How to use the connection pool & get connection & after using it how to release it?


In my project folder I created META-INF folder then I wrote context.xml inside the folder.

    
<Context path="/MyProj" docBase="MyProj" debug="5" reloadable="true" crossContext="true">
	<Resource name="jdbc/someDB" 
			  auth="Container"
			  type="javax.sql.DataSource" 
			  removeAbandoned="true"
			  logAbandoned="true"
			  removeAbandonedTimeout="30" 
			  maxActive="100"
			  maxIdle="30" 
			  maxWait="15000" 
			  username="*****"
			  password="******"
			  driverClassName="com.mysql.jdbc.Driver"
			  url="jdbc:mysql://localhost:3306/MyProj" />
</Context>

I was not sure but I wrote the above class(in previous message) to provide access to the datasource.

Then I did one entry in web.xml:

    
<resource-ref>
  <description>DB Connection</description>
  <res-ref-name>jdbc/someDB</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
 </resource-ref>

[Deepak Bala]

Simply close the connection after you are done. The Connection pool is responsible for reclaiming it.

[kavin clain]

Thank you Deepak.

I state three things here: one the DBBoard class providing DataSource access to get Connection. and other is configuration of DataSource.

Could you please tell me is it not the correct way to use Tomcat 5.5 connection pool? If not then what is the correct way?
As in previous message by you and Peter suggesting to use Connection Pool provided by container, I think I made some mistake here the way accessing the connection pool.

[Deepak Bala]

Your first post did not mention a DBCP framework working to back the data source. Which is why we raised the point.

[kavin clain]

Thanks again. It means the configuration part is correct.
And what about the class to getEnvironmentContext, getDataSource & getConnection. Is this implementation correct? please suggest if any changes need to incorporate!

Do I synchronize the getConnection method.

public static syncronized Connection getConnection(){...}