1. JDBC Data source and Connection pooling 1 JDBC Data sources and Connection pooling

2. JDBC Data source and Connection pooling 2 Getting a connection, 33 "Old" way of getting a connection –DriverManager.getConnection(url, user, pw); "New" way of getting a connection –DataSource ds = … –ds.getConnection(); Data source has URL, username, password –interface javax.sql.DataSourceJDK 1.4 –Example DataSourceExample.java

3. JDBC Data source and Connection pooling 3 Different connections, 34 A data source object may produce 3 kinds of connections –basic connections –pooled connections more on that little later –connections for distributed connections no more on that subject now!

4. JDBC Data source and Connection pooling 4 Long or short lived connections? Problems –It takes a relatively long time to open / close a connection Naive solution: Keep the connection open "forever" –A DBMS can have N open connections Naive solutions: Close connections as soon as possible –Naive solutions are conflicting –Combined solution Connection pool!

5. JDBC Data source and Connection pooling 5 Connection pool, 38 Ideas –The application (server) allocates a pool of connections to the database (e.g. 10 connections) –Applications programmers don't create connections, but borrows a connection the from the pool. Advantages –Connections are "recycled" –Few physical connections Implemented by driver –Old days: implemented by application programmer Example PooledConnection1.java

6. JDBC Data source and Connection pooling 6 JDBC vs. Oracle API JDBC, javax.sql –DataSource produces Connection –ConnectionPoolDataSource produces PooledConnection Oracle, oracle.jdbc.pool –OracleDataSource produces Connection –OracleConnectionPoolDataSource produces PooledConnection –Oracle factories produces "Sun objects".

7. JDBC Data source and Connection pooling 7 Data source and connection pool Mainly used with servers –J2EE / EJB application server –Web-server (e.g. Apache Tomcat) Data source object –deployed with the server –used by application programmers Usage in Servlets / JSP –deploy with Apache Tomcat –doGet(…) acquire connection from pool query database "close" connection (back to pool)