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Rather than configuring the connection manager factory related MBeans discussed in the previous section via a mbean services deployment descriptor, JBoss provides a simplified datasource centric descriptor. This is transformed into the standard jboss-service.xml
MBean services deployment descriptor using a XSL transform applied by the org.jboss.deployment.XSLSubDeployer
included in the jboss-jca.sar
deployment. The simplified configuration descriptor is deployed the same as other deployable components. The descriptor must be named using a *-ds.xml
pattern in order to be recognized by the XSLSubDeployer
.
The schema for the top-level datasource elements of the *-ds.xml
configuration deployment file is shown in Figure 13.1, “The simplified JCA DataSource configuration descriptor top-level schema elements”.
Multiple datasource configurations may be specified in a configuration deployment file. The child elements of the datasources root are:
mbean
: Any number mbean elements may be specified to define MBean services that should be included in the jboss-service.xml
descriptor that results from the transformation. This may be used to configure services used by the datasources.
no-tx-datasource
: This element is used to specify the (org.jboss.resource.connectionmanager
) NoTxConnectionManager
service configuration. NoTxConnectionManager
is a JCA connection manager with no transaction support. The no-tx-datasource
child element schema is given in Figure 13.2, “The non-transactional DataSource configuration schema”.
local-tx-datasource
: This element is used to specify the (org.jboss.resource.connectionmanager
) LocalTxConnectionManager
service configuration. LocalTxConnectionManager
implements a ConnectionEventListener
that implements XAResource
to manage transactions through the transaction manager. To ensure that all work in a local transaction occurs over the same ManagedConnection
, it includes a xid to ManagedConnection
map. When a Connection is requested or a transaction started with a connection handle in use, it checks to see if a ManagedConnection
already exists enrolled in the global transaction and uses it if found. Otherwise, a free ManagedConnection
has its LocalTransaction
started and is used. The local-tx-datasource
child element schema is given in Figure 13.3, “The non-XA DataSource configuration schema”
xa-datasource
: This element is used to specify the (org.jboss.resource.connectionmanager
) XATxConnectionManager
service configuration. XATxConnectionManager
implements a ConnectionEventListener
that obtains the XAResource
to manage transactions through the transaction manager from the adaptor ManagedConnection
. To ensure that all work in a local transaction occurs over the same ManagedConnection
, it includes a xid to ManagedConnection
map. When a Connection
is requested or a transaction started with a connection handle in use, it checks to see if a ManagedConnection
already exists enrolled in the global transaction and uses it if found. Otherwise, a free ManagedConnection
has its LocalTransaction
started and is used. The xa-datasource
child element schema is given in Figure 13.4, “The XA DataSource configuration schema”.
ha-local-tx-datasource
: This element is identical to local-tx-datasource
, with the addition of the experimental datasource failover capability allowing JBoss to failover to an alternate database in the event of a database failure.
ha-xa-datasource
: This element is identical to xa-datasource
, with the addition of the experimental datasource failover capability allowing JBoss to failover to an alternate database in the event of a database failure.
Elements that are common to all datasources include:
jndi-name
: The JNDI name under which the DataSource
wrapper will be bound. Note that this name is relative to the java:/
context, unless use-java-context
is set to false. DataSource
wrappers are not usable outside of the server VM, so they are normally bound under the java:/
, which isn't shared outside the local VM.
use-java-context
: If this is set to false the the datasource will be bound in the global JNDI context rather than the java:
context.
user-name
: This element specifies the default username used when creating a new connection. The actual username may be overridden by the application code getConnection
parameters or the connection creation context JAAS Subject.
password
: This element specifies the default password used when creating a new connection. The actual password may be overridden by the application code getConnection
parameters or the connection creation context JAAS Subject.
application-managed-security
: Specifying this element indicates that connections in the pool should be distinguished by application code supplied parameters, such as from getConnection(user, pw)
.
security-domain
: Specifying this element indicates that connections in the pool should be distinguished by JAAS Subject based information. The content of the security-domain
is the name of the JAAS security manager that will handle authentication. This name correlates to the JAAS login-config.xml
descriptor application-policy/name
attribute.
security-domain-and-application
: Specifying this element indicates that connections in the pool should be distinguished both by application code supplied parameters and JAAS Subject based information. The content of the security-domain
is the name of the JAAS security manager that will handle authentication. This name correlates to the JAAS login-config.xml
descriptor application-policy/name
attribute.
min-pool-size : This element specifies the minimum number of connections a pool should hold. These pool instances are not created until an initial request for a connection is made. This default to 0.
max-pool-size
: This element specifies the maximum number of connections for a pool. No more than the max-pool-size
number of connections will be created in a pool. This defaults to 20.
blocking-timeout-millis : This element specifies the maximum time in milliseconds to block while waiting for a connection before throwing an exception. Note that this blocks only while waiting for a permit for a connection, and will never throw an exception if creating a new connection takes an inordinately long time. The default is 5000.
idle-timeout-minutes
: This element specifies the maximum time in minutes a connection may be idle before being closed. The actual maximum time depends also on the IdleRemover
scan time, which is 1/2 the smallest idle-timeout-minutes of any pool.
new-connection-sql : This is a SQL statement that should be executed when a new connection is created. This can be used to configure a connection with database specific settings not configurable via connection properties.
check-valid-connection-sql
: This is a SQL statement that should be run on a connection before it is returned from the pool to test its validity to test for stale pool connections. An example statement could be: select count(*) from x
.
exception-sorter-class-name
: This specifies a class that implements the org.jboss.resource.adapter.jdbc.ExceptionSorter
interface to examine database exceptions to determine whether or not the exception indicates a connection error. Current implementations include:
org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter
org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter
org.jboss.resource.adapter.jdbc.vendor.SybaseExceptionSorter
org.jboss.resource.adapter.jdbc.vendor.InformixExceptionSorte
valid-connection-checker-class-name
: This specifies a class that implements the org.jboss.resource.adapter.jdbc.ValidConnectionChecker
interface to provide a SQLException isValidConnection(Connection e)
method that is called with a connection that is to be returned from the pool to test its validity. This overrides the check-valid-connection-sql
when present. The only provided implementation is org.jboss.resource.adapter.jdbc.vendor.OracleValidConnectionChecker
.
track-statements
: This boolean element specifies whether to check for unclosed statements when a connection is returned to the pool. If true, a warning message is issued for each unclosed statement. If the log4j category org.jboss.resource.adapter.jdbc.WrappedConnection
has trace level enabled, a stack trace of the connection close call is logged as well. This is a debug feature that can be turned off in production.
prepared-statement-cache-size : This element specifies the number of prepared statements per connection in an LRU cache, which is keyed by the SQL query. Setting this to zero disables the cache.
depends
: The depends
element specifies the JMX ObjectName
string of a service that the connection manager services depend on. The connection manager service will not be started until the dependent services have been started.
type-mapping
: This element declares a default type mapping for this datasource. The type mapping should match a type-mapping/name
element from standardjbosscmp-jdbc.xml
.
Additional common child elements for both no-tx-datasource
and local-tx-datasource
include:
connection-url
: This is the JDBC driver connection URL string, for example, jdbc:hsqldb:hsql://localhost:1701
.
driver-class
: This is the fully qualified name of the JDBC driver class, for example, org.hsqldb.jdbcDriver
.
connection-property
: The connection-property
element allows you to pass in arbitrary connection properties to the java.sql.Driver.connect(url, props)
method. Each connection-property
specifies a string name/value pair with the property name coming from the name attribute and the value coming from the element content.
Elements in common to the local-tx-datasource
and xa-datasource
are:
transaction-isolation
: This element specifies the java.sql.Connection
transaction isolation level to use. The constants defined in the Connection interface are the possible element content values and include:
TRANSACTION_READ_UNCOMMITTED
TRANSACTION_READ_COMMITTED
TRANSACTION_REPEATABLE_READ
TRANSACTION_SERIALIZABLE
TRANSACTION_NONE
no-tx-separate-pools : The presence of this element indicates that two connection pools are required to isolate connections used with JTA transaction from those used without a JTA transaction. The pools are lazily constructed on first use. Its use case is for Oracle (and possibly other vendors) XA implementations that don't like using an XA connection with and without a JTA transaction.
The unique xa-datasource
child elements are:
track-connection-by-tx
: Specifying a true value for this element makes the connection manager keep an xid to connection map and only put the connection back in the pool when the transaction completes and all the connection handles are closed or disassociated (by the method calls returning). As a side effect, we never suspend and resume the xid on the connection's XAResource
. This is the same connection tracking behavior used for local transactions.
The XA spec implies that any connection may be enrolled in any transaction using any xid for that transaction at any time from any thread (suspending other transactions if necessary). The original JCA implementation assumed this and aggressively delisted connections and put them back in the pool as soon as control left the EJB they were used in or handles were closed. Since some other transaction could be using the connection the next time work needed to be done on the original transaction, there is no way to get the original connection back. It turns out that most XADataSource
driver vendors do not support this, and require that all work done under a particular xid go through the same connection.
xa-datasource-class
: The fully qualified name of the javax.sql.XADataSource
implementation class, for example, com.informix.jdbcx.IfxXADataSource
.
xa-datasource-property
: The xa-datasource-property
element allows for specification of the properties to assign to the XADataSource
implementation class. Each property is identified by the name attribute and the property value is given by the xa-datasource-property
element content. The property is mapped onto the XADataSource
implementation by looking for a JavaBeans style getter method for the property name. If found, the value of the property is set using the JavaBeans setter with the element text translated to the true property type using the java.beans.PropertyEditor
for the type.
isSameRM-override-value
: A boolean flag that allows one to override the behavior of the javax.transaction.xa.XAResource.isSameRM(XAResource xaRes)
method behavior on the XA managed connection. If specified, this value is used unconditionally as the isSameRM(xaRes)
return value regardless of the xaRes
parameter.
The failover options common to ha-xa-datasource
and ha-local-tx-datasource
are:
url-delimeter : This element specifies a character used to separate multiple JDBC URLs.
url-property
: In the case of XA datasources, this property specifies the name of the xa-datasource-property
that contains the list of JDBC URLs to use.