9 Data Sources and URLs

Overview of Oracle Data Source Support for JNDI

The JNDI standard provides a way for applications to find and access remote services and resources. These services can be any enterprise services. However, for a JDBC application, these services would include database connections and services.

JNDI allows an application to use logical names in accessing these services, removing vendor-specific syntax from application code. JNDI has the functionality to associate a logical name with a particular source for a desired service.

All Oracle JDBC data sources are JNDI-referenceable. The developer is not required to use this functionality, but accessing databases through JNDI logical names makes the code more portable.

Features and Properties of Data Sources

By using the data source functionality with JNDI, you do not need to register the vendor-specific JDBC driver class name and you can use logical names for URLs and other properties. This ensures that the code for opening database connections is portable to other environments.

The DataSource Interface and Oracle Implementation

A JDBC data source is an instance of a class that implements the standard javax.sql.DataSource interface:

public interface DataSource
{
   Connection getConnection() throws SQLException;
   Connection getConnection(String username, String password)
      throws SQLException;
   ...
}

Oracle implements this interface with the OracleDataSource class in the oracle.jdbc.pool package. The overloaded getConnection method returns a physical connection to the database.

To use other values, you can set properties using appropriate setter methods. For alternative user names and passwords, you can also use the getConnection method that takes these parameters as input. This would take priority over the property settings.

Properties of DataSource

The OracleDataSource class, as with any class that implements the DataSource interface, provides a set of properties that can be used to specify a database to connect to. These properties follow the JavaBeans design pattern.

Table 9-1 and Table 9-2 list OracleDataSource properties. The properties in Table 9-1 are standard properties according to the Sun Microsystems specification. The properties in Table 9-2 are Oracle extensions.

The OracleDataSource class implements the following setter and getter methods for the standard properties:

• public synchronized void setDatabaseName(String dbname)

• public synchronized String getDatabaseName()

• public synchronized void setDataSourceName(String dsname)

• public synchronized String getDataSourceName()

• public synchronized void setDescription(String desc)

• public synchronized String getDescription()

• public synchronized void setNetworkProtocol(String np)

• public synchronized String getNetworkProtocol()

• public synchronized void setPassword(String pwd)

• public synchronized void setPortNumber(int pn)

• public synchronized int getPortNumber()

• public synchronized void setServerName(String sn)

• public synchronized String getServerName()

• public synchronized void setUser(String user)

• public synchronized String getUser()

The OracleDataSource class implements the following setXXX and getXXX methods for the Oracle extended properties:

• String getConnectionCacheName()

• java.util.Properties getConnectionCacheProperties()

• void setConnectionCacheProperties(java.util.Properties cp)

• java.util.Properties getConnectionProperties()

• void setConnectionProperties(java.util.Properties cp)

• boolean getConnectionCachingEnabled()

• void setImplicitCachingEnabled()

• String getDriverType()

• void setDriverType(String dt)

• String getURL()

• void setURL(String url)

• String getTNSEntryName()

• void setTNSEntryName(String tns)

• boolean getNativeXA()

• void setNativeXA(boolean nativeXA)

• String getONSConfiguration()

• void setONSConfiguration(String onsConfig)

If you are using the server-side internal driver, that is, the driverType property is set to kprb, then any other property settings are ignored.

If you are using the JDBC Thin or OCI driver, then note the following:

• A URL setting can include settings for user and password, as in the following example, in which case this takes precedence over individual user and password property settings:

  jdbc:oracle:thin:scott/tiger@localhost:1521:orcl
  
  

• Settings for user and password are required, either directly through the URL setting or through the getConnection call. The user and password settings in a getConnection call take precedence over any property settings.

• If the url property is set, then any tnsEntry, driverType, portNumber, networkProtocol, serverName, and databaseName property settings are ignored.

• If the tnsEntry property is set, which presumes the url property is not set, then any databaseName, serverName, portNumber, and networkProtocol settings are ignored.

• If you are using an OCI driver, which presumes the driverType property is set to oci, and the networkProtocol is set to ipc, then any other property settings are ignored.

Also, note that getConnectionCacheName() will return the name of the cache only if the ConnectionCacheName property of the data source is set after caching is enabled on the data source.

Creating a Data Source Instance and Connecting

This section shows an example of the most basic use of a data source to connect to a database, without using JNDI functionality. Note that this requires vendor-specific, hard-coded property settings.

Create an OracleDataSource instance, initialize its connection properties as appropriate, and get a connection instance, as in the following example:

OracleDataSource ods = new OracleDataSource();
ods.setDriverType("oci");
ods.setServerName("dlsun999");
ods.setNetworkProtocol("tcp");
ods.setDatabaseName("816");
ods.setPortNumber(1521);
ods.setUser("scott");
ods.setPassword("tiger");
Connection conn = ods.getConnection();

Or, optionally, override the user name and password, as follows:

Connection conn = ods.getConnection("bill", "lion");

Creating a Data Source Instance, Registering with JNDI, and Connecting

This section exhibits JNDI functionality in using data sources to connect to a database. Vendor-specific, hard-coded property settings are required only in the portion of code that binds a data source instance to a JNDI logical name. From that point onward, you can create portable code by using the logical name in creating data sources from which you will get your connection instances.

Initialize Data Source Properties

Create an OracleDataSource instance, and then initialize its properties as appropriate, as in the following example:

OracleDataSource ods = new OracleDataSource();
ods.setDriverType("oci");
ods.setServerName("dlsun999");
ods.setNetworkProtocol("tcp");
ods.setDatabaseName("816");
ods.setPortNumber(1521);
ods.setUser("scott");
ods.setPassword("tiger");

Register the Data Source

Once you have initialized the connection properties of the OracleDataSource instance ods, as shown in the preceding example, you can register this data source instance with JNDI, as in the following example:

Context ctx = new InitialContext();
ctx.bind("jdbc/sampledb", ods);

Calling the JNDI InitialContext() constructor creates a Java object that references the initial JNDI naming context. System properties, which are not shown, instruct JNDI which service provider to use.

The ctx.bind call binds the OracleDataSource instance to a logical JNDI name. This means that anytime after the ctx.bind call, you can use the logical name jdbc/sampledb in opening a connection to the database described by the properties of the OracleDataSource instance ods. The logical name jdbc/sampledb is logically bound to this database.

The JNDI namespace has a hierarchy similar to that of a file system. In this example, the JNDI name specifies the subcontext jdbc under the root naming context and specifies the logical name sampledb within the jdbc subcontext.

The Context interface and InitialContext class are in the standard javax.naming package.

Open a Connection

To perform a lookup and open a connection to the database logically bound to the JNDI name, use the logical JNDI name. Doing this requires casting the lookup result, which is otherwise a Java Object, to OracleDataSource and then using its getConnection method to open the connection.

Here is an example:

OracleDataSource odsconn = (OracleDataSource)ctx.lookup("jdbc/sampledb");
Connection conn = odsconn.getConnection();

Supported Connection Properties

Table 9-3 provides the detailed list of connection properties that Oracle JDBC drivers support.

^Footnote 1 All these entries are actually strings containing a value of the type listed.

Using Roles for SYS Login

To specify the role for the SYS login, use the internal_logon connection property. To logon as SYS, set the internal_logon connection property to SYSDBA or SYSOPER.

For a bequeath connection, we can get a connection as SYS by setting the internal_logon property. For a remote connection, we need additional password file setting procedures.

Configuring Database Remote Login

Before the JDBC Thin driver can connect to the database as SYSDBA, you must configure the user, because the Oracle Database security system requires a password file for remote connections as an administrator. Perform the following:

1. Set a password file on the server side or on the remote database, using the orapwd password utility. You can add a password file for user sys as follows:

   • In UNIX

     orapwd file=$ORACLE_HOME/dbs/orapw password=sys entries=200
     
     

   • In Microsoft Windows

     orapwd file=%ORACLE_HOME%\database\PWDsid_name.ora password=sys entries=200
     
     

   file must be the name of the password file. password is the password for the user SYS. It can be altered using the ALTER USER statement in SQL Plus. You should set entries to a value higher than the number of entries you expect.

   The syntax for the password file name is different on Microsoft Windows and UNIX.

   See Also:

   Oracle Database Administrator's Guide

2. Enable remote login as sysdba. This step grants SYSDBA and SYSOPER system privileges to individual users and lets them connect as themselves.

   Stop the database, and add the following line to initservice_name.ora, in UNIX, or init.ora, in Microsoft Windows:

   remote_login_passwordfile=exclusive
   
   

   The initservice_name.ora file is located at ORACLE_HOME/dbs/ and also at ORACLE_HOME/admin/db_name/pfile/. Ensure that you keep the two files synchronized.

   The init.ora file is located at %ORACLE_BASE%\ADMIN\db_name\pfile\.

3. Change the password for the SYS user. This is an optional step.

   SQL> alter user sys identified by sys;
   
   

4. Verify whether SYS has the SYSDBA privilege.

   SQL> select * from v$pwfile_users;
   USERNAME                         SYSDB        SYSOP
   ----------------------           ---------    ---------
   SYS                              TRUE         TRUE
   
   

5. Restart the remote database.

//This example works regardless of language settings of the database.
 /** case of remote connection using sys **/
import java.sql.*;
import oracle.jdbc.*;
import oracle.jdbc.pool.*;
// create an OracleDataSource
OracleDataSource ods = new OracleDataSource();
// set connection properties
java.util.Properties prop = new java.util.Properties();
prop.put("user", "sys");
prop.put("password", "sys");
prop.put("internal_logon", "sysoper");
ods.setConnectionProperties(prop);
// set the url
// the url can use oci driver as well as:
// url = "jdbc:oracle:oci8:@inst1"; the inst1 is a remote database
String url = "jdbc:oracle:thin:@//myHost:1521/service_name";
ods.setURL(url);
// get the connection
Connection conn = ods.getConnection();
...

Bequeath Connection and SYS Logon

The following example illustrates how to use the internal_logon and SYSDBA arguments to specify the SYS login. This example works regardless of the database's national-language settings of the database.

/** Example of bequeath connection **/
import java.sql.*;
import oracle.jdbc.*;
import oracle.jdbc.pool.*;
 
// create an OracleDataSource instance
OracleDataSource ods = new OracleDataSource();
 
// set neccessary properties
java.util.Properties prop = new java.util.Properties();
prop.put("user", "sys");
prop.put("password", "sys");
prop.put("internal_logon", "sysdba");
ods.setConnectionProperties(prop);
 
// the url for bequeath connection
String url = "jdbc:oracle:oci8:@";
ods.setURL(url);
 
// retrieve the connection
Connection conn = ods.getConnection();
... 

Properties for Oracle Performance Extensions

Some of the connection properties are for use with Oracle performance extensions. Setting these properties is equivalent to using corresponding methods on the OracleConnection object, as follows:

• Setting the defaultRowPrefetch property is equivalent to calling setDefaultRowPrefetch.

  See Also:

  "Oracle Row Prefetching"

• Setting the remarksReporting property is equivalent to calling setRemarksReporting.

  See Also:

  "DatabaseMetaData TABLE_REMARKS Reporting"

• Setting the defaultBatchValue property is equivalent to calling setDefaultExecuteBatch

  See Also:

  "Oracle Update Batching"

Example

The following example shows how to use the put method of the java.util.Properties class, in this case, to set Oracle performance extension parameters.

//import packages and register the driver
import java.sql.*;
import java.math.*;
import oracle.jdbc.*;
import oracle.jdbc.pool.OracleDataSource;

//specify the properties object
java.util.Properties info = new java.util.Properties();
info.put ("user", "scott");
info.put ("password", "tiger");
info.put ("defaultRowPrefetch","20");
info.put ("defaultBatchValue", "5");

//specify the datasource object 
OracleDataSource ods = new OracleDataSource();
ods.setURL("jdbc:oracle:thin:@//myhost:1521/orcl");
ods.setUser("scott");
ods.setPassword("tiger");
ods.setConnectionProperties(info);
...

Logging and Tracing

The data source facility offers a way to register a character stream for JDBC to use as output for error logging and tracing information. This facility enables tracing specific to a particular data source instance. If you want all data source instances to use the same character stream, then you must register the stream with each data source instance individually.

The OracleDataSource class implements the following standard data source methods for logging and tracing:

• public synchronized void setLogWriter(PrintWriter pw)

• public synchronized PrintWriter getLogWriter()

The PrintWriter class is in the standard java.io package.