Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer's Guide

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# Chapter 11 Using the JDBC API for Database Access

This chapter describes how to use the JavaTM Database Connectivity (JDBCTM) API for database access with the Sun Java System Application Server. This chapter also provides high level JDBC implementation instructions for servlets and EJBTM components using the Application Server. The Application Server supports the JDBC 3.0 API, which encompasses the JDBC 2.0 Optional Package API.

The JDBC specifications are available at `http://java.sun.com/products/jdbc/download.html`.

A useful JDBC tutorial is located at `http://java.sun.com/docs/books/tutorial/jdbc/index.html`.

For explanations of two-tier and three-tier database access models, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

Note –

The Application Server does not support connection pooling or transactions for an application’s database access if it does not use standard J2EETM `DataSource` objects.

This chapter discusses the following topics:

- General Steps for Creating a JDBC Resource

- Creating Applications That Use the JDBC API

- Configurations for Specific JDBC Drivers

# General Steps for Creating a JDBC Resource

To prepare a JDBC resource for use in J2EE applications deployed to the Application Server, perform the following tasks:

- Integrating the JDBC Driver

- Creating a Connection Pool

- Testing a Connection Pool

- Creating a JDBC Resource

For information about how to configure some specific JDBC drivers, see the Configurations for Specific JDBC Drivers.

## Integrating the JDBC Driver

To use JDBC features, you must choose a JDBC driver to work with the Application Server, then you must set up the driver. This section covers these topics:

- Supported Database Drivers

- Making the JDBC Driver JAR Files Accessible

### Supported Database Drivers

Supported JDBC drivers are those that have been fully tested by Sun. For a list of the JDBC drivers currently supported by the Application Server, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Release Notes. For configurations of supported and other drivers, see Configurations for Specific JDBC Drivers.

Note –

Because the drivers and databases supported by the Application Server are constantly being updated, and because database vendors continue to upgrade their products, always check with Sun technical support for the latest database support information.

### Making the JDBC Driver JAR Files Accessible

To integrate the JDBC driver into a Application Server domain, copy the JAR files into the domain-dir`/lib/ext` directory, then restart the server. This makes classes accessible to any application or module across the domain. For more information about Application Server classloaders, see Classloaders.

## Creating a Connection Pool

When you create a connection pool that uses JDBC technology (a JDBC connection pool) in the Application Server, you can define many of the characteristics of your database connections.

You can create a JDBC connection pool in one of these ways:

- In the Administration Console, open the Resources component, open the JDBC component, and select Connection Pools. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

- Use the `asadmin create-jdbc-connection-pool` command. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Reference Manual.

## Testing a Connection Pool

You can test a JDBC connection pool for usability in one of these ways:

- In the Administration Console, open the Resources component, open the JDBC component, select Connection Pools, and select the connection pool you want to test. Then select the Ping button in the top right corner of the page. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

- Use the `asadmin ping-connection-pool` command. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Reference Manual

Both these commands fail and display an error message unless they successfully connect to the connection pool.

For information about how to tune a connection pool, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Performance Tuning Guide.

## Creating a JDBC Resource

A JDBC resource, also called a data source, lets you make connections to a database using `getConnection()`. Create a JDBC resource in one of these ways:

- In the Administration Console, open the Resources component, open the JDBC component, and select JDBC Resources. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

- Use the `asadmin create-jdbc-resource` command. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Reference Manual.

# Creating Applications That Use the JDBC API

An application that uses the JDBC API is an application that looks up and connects to one or more databases. This section covers these topics:

- Sharing Connections

- Obtaining a Physical Connection from a Wrapped Connection

- Using Non-Transactional Connections

- Using JDBC Transaction Isolation Levels

## Sharing Connections

When multiple connections acquired by an application use the same JDBC resource, the connection pool provides connection sharing within the same transaction scope. For example, suppose Bean A starts a transaction and obtains a connection, then calls a method in Bean B. If Bean B acquires a connection to the same JDBC resource with the same sign-on information, and if Bean A completes the transaction, the connection can be shared.

Connections obtained through a resource are shared only if the resource reference declared by the J2EE component allows it to be shareable. This is specified in a component’s deployment descriptor by setting the `res-sharing-scope` element to `Shareable` for the particular resource reference. To turn off connection sharing, set `res-sharing-scope` to `Unshareable`.

For general information about connections and JDBC URLs, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

## Obtaining a Physical Connection from a Wrapped Connection

The `DataSource` implementation in the Application Server provides a `getConnection` method that retrieves the JDBC driver’s `SQLConnection` from the Application Server’s `Connection` wrapper. The method signature is as follows:

    public java.sql.Connection getConnection(java.sql.Connection con)
    throws java.sql.SQLException

For example:

    InitialContext ctx = new InitialContext();
    com.sun.appserv.DataSource ds = (com.sun.appserv.DataSource)
       ctx.lookup("jdbc/MyBase");
    Connection con = ds.getConnection();
    Connection drivercon = ds.getConnection(con);
    // Do db operations.
    con.close();

## Using Non-Transactional Connections

The `DataSource` implementation in the Application Server provides a `getNonTxConnection` method, which retrieves a JDBC connection that is not in the scope of any transaction. There are two variants, as follows:

    public java.sql.Connection getNonTxConnection() throws java.sql.SQLException

    public java.sql.Connection getNonTxConnection(String user, String password)
    throws java.sql.SQLException

Another way to get a non-transactional connection is to create a resource with the JNDI name ending in `__nontx`. This forces all connections looked up using this resource to be non transactional.

Typically, a connection is enlisted in the context of the transaction in which a `getConnection` call is invoked. However, a non-transactional connection is not enlisted in a transaction context even if a transaction is in progress.

The main advantage of using non-transactional connections is that the overhead incurred in enlisting and delisting connections in transaction contexts is avoided. However, use such connections carefully. For example, if a non-transactional connection is used to query the database while a transaction is in progress that modifies the database, the query retrieves the unmodified data in the database. This is because the in-progress transaction hasn’t committed. For another example, if a non-transactional connection modifies the database and a transaction that is running simultaneously rolls back, the changes made by the non-transactional connection are not rolled back.

Here is a typical use case for a non-transactional connection: a component that is updating a database in a transaction context spanning over several iterations of a loop can refresh cached data by using a non-transactional connection to read data before the transaction commits.

## Using JDBC Transaction Isolation Levels

For general information about transactions, see Chapter 12, Using the Transaction Serviceand the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide. For information about last agent optimization, which can improve performance, see Transaction Scope.

Not all database vendors support all transaction isolation levels available in the JDBC API. The Application Server permits specifying any isolation level your database supports. The following table defines transaction isolation levels.

Table 11–1 Transaction Isolation Levels

Transaction Isolation Level | Description
--- | ---
`TRANSACTION_READ_UNCOMMITTED` | Dirty reads, non-repeatable reads and phantom reads can occur.
`TRANSACTION_READ_COMMITTED` | Dirty reads are prevented; non-repeatable reads and phantom reads can occur.
`TRANSACTION_REPEATABLE_READ` | Dirty reads and non-repeatable reads are prevented; phantom reads can occur.
`TRANSACTION_SERIALIZABLE` | Dirty reads, non-repeatable reads and phantom reads are prevented.

Note that you cannot call `setTransactionIsolation()` during a transaction.

You can set the default transaction isolation level for a JDBC connection pool. For details, see Creating a Connection Pool.

To verify that a level is supported by your database management system, test your database programmatically using the `supportsTransactionIsolationLevel()` method in `java.sql.DatabaseMetaData`, as shown in the following example:

    java.sql.DatabaseMetaData db;
    if (db.supportsTransactionIsolationLevel(TRANSACTION_SERIALIZABLE)
       { Connection.setTransactionIsolation(TRANSACTION_SERIALIZABLE); }

For more information about these isolation levels and what they mean, see the JDBC 3.0 API specification.

Note –

Applications that change the isolation level on a pooled connection programmatically risk polluting the pool, which can lead to errors.

# Configurations for Specific JDBC Drivers

Application Server 8.1 is designed to support connectivity to any database management system with a corresponding JDBC driver. The following JDBC driver and database combinations are supported. These combinations have been tested with Application Server 8.1 and are found to be J2EE compatible. They are also supported for CMP.

- PointBase Type 4 Driver

- Sun Java System JDBC Driver for DB2 Databases

- Sun Java System JDBC Driver for Oracle 8.1.7 and 9.x Databases

- Sun Java System JDBC Driver for Microsoft SQL Server Databases

- Sun Java System JDBC Driver for Sybase Databases

- IBM DB2 8.1 Type 2 Driver

- JConnect Type 4 Driver for Sybase ASE 12.5 Databases

For an up to date list of currently supported JDBC drivers, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Release Notes.

Other JDBC drivers can be used with Application Server 8.1, but J2EE compliance tests have not been completed with these drivers. Although Sun offers no product support for these drivers, Sun offers limited support of the use of these drivers with Application Server 8.1.

- Inet Oraxo JDBC Driver for Oracle 8.1.7 and 9.x Databases

- Inet Merlia JDBC Driver for Microsoft SQL Server Databases

- Inet Sybelux JDBC Driver for Sybase Databases

- Oracle Thin Type 4 Driver for Oracle 8.1.7 and 9.x Databases

- OCI Oracle Type 2 Driver for Oracle 8.1.7 and 9.x Databases

- IBM Informix Type 4 Driver

- MM MySQL Type 4 Driver

- CloudScape 5.1 Type 4 Driver

For details about how to integrate a JDBC driver and how to use the Administration Console or the command line interface to implement the configuration, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

Note –

An Oracle database user running the `capture-schema` command needs ANALYZE ANY TABLE privileges if that user does not own the schema. These privileges are granted to the user by the database administrator. For information about `capture-schema`, see Using the capture-schema Utility.

## PointBase Type 4 Driver

The PointBase JDBC driver is included with the Application Server by default, except for the Solaris bundled installation, which does not include PointBase. Therefore, unless you have the Solaris bundled installation, you do not need to integrate this JDBC driver with the Application Server.

PointBase is intended for evaluation use only, not for production or deployment use.

The JAR file for the PointBase driver is `pbclient.jar`.

Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `PointBase`

- DataSource Classname:Specify one of the following:

      com.pointbase.jdbc.jdbcDataSource
      com.pointbase.xa.xaDataSource

- Properties:

  - `user` - Specify the database user.

  - `password` - Specify the database password.

  - `databaseName` - Specify the URL of the database. The syntax is as follows:

        jdbc:pointbase:server://server:port/dbname,new

## Sun Java System JDBC Driver for DB2 Databases

The JAR files for this driver are `smbase.jar`, `smdb2.jar`, and `smutil.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `DB2`

- DataSource Classname: `com.sun.sql.jdbcx.db2.DB2DataSource`

- Properties:

  - `serverName` - Specify the host name or IP address of the database server.

  - `portNumber` - Specify the port number of the database server.

  - `databaseName` - Set as appropriate.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

- URL: `jdbc:sun:db2://`serverName`:`portNumber`;databaseName=`databaseName

## Sun Java System JDBC Driver for Oracle 8.1.7 and 9.x Databases

The JAR files for this driver are `smbase.jar`, `smoracle.jar`, and `smutil.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Oracle`

- DataSource Classname: `com.sun.sql.jdbcx.oracle.OracleDataSource`

- Properties:

  - `serverName` - Specify the host name or IP address of the database server.

  - `portNumber` - Specify the port number of the database server.

  - `SID` - Set as appropriate.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

- URL: `jdbc:sun:oracle://`serverName`[:`portNumber`][;SID=`databaseName`]`

## Sun Java System JDBC Driver for Microsoft SQL Server Databases

The JAR files for this driver are `smbase.jar`, `smsqlserver.jar`, and `smutil.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `mssql`

- DataSource Classname: `com.sun.sql.jdbcx.sqlserver.SQLServerDataSource`

- Properties:

  - `serverName` - Specify the host name or IP address and the port of the database server.

  - `portNumber` - Specify the port number of the database server.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `selectMethod` - Set to `cursor`.

- URL: `jdbc:sun:sqlserver://`serverName`[:`portNumber`]`

## Sun Java System JDBC Driver for Sybase Databases

The JAR files for this driver are `smbase.jar`, `smsybase.jar`, and `smutil.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Sybase`

- DataSource Classname: `com.sun.sql.jdbcx.sybase.SybaseDataSource`

- Properties:

  - `serverName` - Specify the host name or IP address of the database server.

  - `portNumber` - Specify the port number of the database server.

  - `databaseName` - Set as appropriate. This is optional.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

- URL: `jdbc:sun:sybase://`serverName`[:`portNumber`]`

## IBM DB2 8.1 Type 2 Driver

The JAR files for the DB2 driver are `db2jcc.jar`, `db2jcc_license_cu.jar`, and `db2java.zip`. Set environment variables as follows:

    LD_LIBRARY_PATH=/usr/db2user/sqllib/lib:${j2ee.home}/lib
    DB2DIR=/opt/IBM/db2/V8.1
    DB2INSTANCE=db2user
    INSTHOME=/usr/db2user
    VWSPATH=/usr/db2user/sqllib
    THREADS_FLAG=native

Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `DB2`

- DataSource Classname: `com.ibm.db2.jcc.DB2SimpleDataSource`

- Properties:

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `databaseName` - Set as appropriate.

  - `driverType` - Set to `2`.

  - `deferPrepares` - Set to `false`.

## JConnect Type 4 Driver for Sybase ASE 12.5 Databases

The JAR file for the Sybase driver is `jconn2.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Sybase`

- DataSource Classname:Specify one of the following:

      com.sybase.jdbc2.jdbc.SybDataSource
      com.sybase.jdbc2.jdbc.SybXADataSource

- Properties:

  - `serverName` - Specify the host name or IP address of the database server.

  - `portNumber` - Specify the port number of the database server.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `databaseName` - Set as appropriate. Do not specify the complete URL, only the database name.

  - `BE_AS_JDBC_COMPLIANT_AS_POSSIBLE` - Set to `true`.

  - `FAKE_METADATA` - Set to `true`.

## Inet Oraxo JDBC Driver for Oracle 8.1.7 and 9.x Databases

The JAR file for the Inet Oracle driver is `Oranxo.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Oracle`

- DataSource Classname: `com.inet.ora.OraDataSource`

- Properties:

  - `user` - Specify the database user.

  - `password` - Specify the database password.

  - `serviceName` - Specify the URL of the database. The syntax is as follows:

        jdbc:inetora:server:port:dbname

    For example:

        jdbc:inetora:localhost:1521:payrolldb

    In this example,`localhost` is the host name of the machine running the Oracle server, `1521` is the Oracle server’s port number, and `payrolldb` is the SID of the database. For more information about the syntax of the database URL, see the Oracle documentation.

  - `serverName` - Specify the host name or IP address of the database server.

  - `port` - Specify the port number of the database server.

  - `streamstolob` - If the size of BLOB or CLOB data types exceeds 4 KB and this driver is used for CMP, this property must be set to `true`.

  - `xa-driver-does-not-support-non-tx-operations` - Set to the value `true`. Optional: only needed if both non-XA and XA connections are retrieved from the same connection pool. Might degrade performance.

    As an alternative to setting this property, you can create two connection pools, one for non-XA connections and one for XA connections.

## Inet Merlia JDBC Driver for Microsoft SQL Server Databases

The JAR file for the Inet Microsoft SQL Server driver is `Merlia.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `mssql`

- DataSource Classname: `com.inet.tds.TdsDataSource`

- Properties:

  - `serverName` - Specify the host name or IP address and the port of the database server.

  - `port` - Specify the port number of the database server.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

## Inet Sybelux JDBC Driver for Sybase Databases

The JAR file for the Inet Sybase driver is `Sybelux.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Sybase`

- DataSource Classname: `com.inet.syb.SybDataSource`

- Properties:

  - `serverName` - Specify the host name or IP address of the database server.

  - `portNumber` - Specify the port number of the database server.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `databaseName` - Set as appropriate. Do not specify the complete URL, only the database name.

## Oracle Thin Type 4 Driver for Oracle 8.1.7 and 9.x Databases

The JAR file for the Oracle driver is `ojdbc14.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Oracle`

- DataSource Classname:Specify one of the following:

      oracle.jdbc.pool.OracleDataSource
      oracle.jdbc.xa.client.OracleXADataSource

- Properties:

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `URL` - Specify the complete database URL using the following syntax:

        jdbc:oracle:thin:[user/password]@host[:port]/service

    For example:

        jdbc:oracle:thin:@localhost:1521:customer_db

  - `xa-driver-does-not-support-non-tx-operations` - Set to the value `true`. Optional: only needed if both non-XA and XA connections are retrieved from the same connection pool. Might degrade performance.

    As an alternative to setting this property, you can create two connection pools, one for non-XA connections and one for XA connections.

  Note –

  You must set the `oracle-xa-recovery-workaround` property in the Transaction Service for recovery of global transactions to work correctly. For details, see Transaction Scope.

  When using this driver, it is not possible to insert more than 2000 bytes of data into a column. To circumvent this problem, use the OCI driver (JDBC type 2).

## OCI Oracle Type 2 Driver for Oracle 8.1.7 and 9.x Databases

The JAR file for the OCI Oracle driver is `ojdbc14.jar`. Make sure that the shared library is available through LD_LIBRARY_PATH and that the ORACLE_HOME property is set. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Oracle`

- DataSource Classname:Specify one of the following:

      oracle.jdbc.pool.OracleDataSource
      oracle.jdbc.xa.client.OracleXADataSource

- Properties:

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `URL` - Specify the complete database URL using the following syntax:

        jdbc:oracle:oci:[user/password]@host[:port]/service

    For example:

        jdbc:oracle:oci:@localhost:1521:customer_db

  - `xa-driver-does-not-support-non-tx-operations` - Set to the value `true`. Optional: only needed if both non-XA and XA connections are retrieved from the same connection pool. Might degrade performance.

    As an alternative to setting this property, you can create two connection pools, one for non-XA connections and one for XA connections.

## IBM Informix Type 4 Driver

Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Informix`

- DataSource Classname:Specify one of the following:

      com.informix.jdbcx.IfxDataSource
      com.informix.jdbcx.IfxXADataSource

- Properties:

  - `serverName` - Specify the Informix database server name.

  - `portNumber` - Specify the port number of the database server.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `databaseName` - Set as appropriate. This is optional.

  - `IfxIFXHost` - Specify the host name or IP address of the database server.

## MM MySQL Type 4 Driver

Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `mysql`

- DataSource Classname: one of the following:

      com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource
      com.mysql.jdbc.jdbc2.optional.MysqlXaConnectionPoolDataSource

- Properties:

  - `serverName` - Specify the host name or IP address of the database server.

  - `port` - Specify the port number of the database server.

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `databaseName` - Set as appropriate.

  - `URL` - If you are using global transactions, you can set this property instead of `serverName`, `port`, and `databaseName`.

    The MM MySQL Type 4 driver doesn’t provide a method to set the required `relaxAutoCommit` property, so you must set it indirectly by setting the `URL` property:

        jdbc:mysql://host:port/database?relaxAutoCommit="true"

## CloudScape 5.1 Type 4 Driver

The JAR files for the CloudScape driver are `db2j.jar`, `db2jtools.jar`, `db2jcview.jar`, `jh.jar`, `db2jcc.jar`, and `db2jnet.jar`. Configure the connection pool using the following settings:

- Name: Use this name when you configure the JDBC resource later.

- Resource Type: Specify the appropriate value.

- Database Vendor: `Cloudscape`

- DataSource Classname: `com.ibm.db2.jcc.DB2DataSource`

- Properties:

  - `user` - Set as appropriate.

  - `password` - Set as appropriate.

  - `databaseName` - Set as appropriate.

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- Next: Chapter 12 Using the Transaction Service

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