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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE datasources
PUBLIC "-//JBoss//DTD JBOSS JCA Config 1.5//EN"
"http://www.jboss.org/j2ee/dtd/jboss-ds_1_5.dtd">
<datasources>
<local-tx-datasource>
<jndi-name>${ds.jndi.name}</jndi-name>
<use-java-context>true</use-java-context>
<connection-url>${ds.connection.url}</connection-url>
<driver-class>${ds.driver.class}</driver-class>
<user-name>${ds.user.name}</user-name>
<password>${ds.password}</password>
</local-tx-datasource>
</datasources>
<!--
The three transaction types you can use are:
local-tx-datasource : Identifies a data source that uses transactions, even distributed
transactions within the local application server, but does not use
distributed transactions among multiple application servers.
no-tx-datasource : Identifies a data source that does not use transactions. This option is not
shown in the example, but would appear in place of the <local-tx-datasource>
tag.
xa-datasource : Identifies a data source that uses distributed transaction among multiple
application servers. This option is not shown in the example, but would
appear in place of the <local-tx-datasource> tag.
So which transaction type should you use? In most cases you will use
<local-tx-datasource> because it handles transactions within a single
application server. If you are clustering your application servers, or want
to use distributed transactions among multiple application servers, then you
should use <xa-datasource>. Note that both <local-tx-datasource> and
<xa-datasource> handle distributed transactions which involve multiple
datasources. The difference is that <local-tx-datasource> handles them only
within a single running application server, while <xa-datasource> handles
them among many running application servers. On the other end of the
spectrum, if your applications only read from the database, then using
<no-tx-datasource> would be appropriate.
WHAT IS XA?
XA is an API defined by The Open Group's Distributed Transaction Processing
model. This model provides communications mechanisms between a Transaction
Monitor and several resource managers which perform updates against
databases. The Transaction Monitor is responsible for coordinating the
individual transactions handled by the resource managers to ensure
transactional semantics when multiple resource managers are involved in a
single transaction.
Within the transaction type, you can specify a wide variety of configuration options. The following
describes the various configuration options in the *-ds.xml file. A complete set of configuration
options, along with a description of each option, can be found in the docs/dtd/jboss-ds_1_5.dtd file.
jndi-name : The name used to reference the data source in your application configurations.
The name is used to look up the data source in the JNDI namespace. The
"java:" prefix is automatically added to this name, so datasources are not
available outside the virtual machine.
use-java-context : When the value of this element is false, you don't use the java:/ prefix on
the JNDI name.
<use-java-context>true</use-java-context> => JNDI name is java:/dataSourceName
<use-java-context>false</use-java-context> => JNDI name is dataSourceName
Note that when this element is excluded, the default value is true
(in which case you use the java:/ prefix).
connection-url : The database-specific URL to the server.
driver-class : The driver you are using for your database.
xa-datasource-class : The class name for the distributed transaction data source.
Valid only for xa-datasource
user-name : The username that is defined to access this data source. In general,
do not use the root username.
password : The password for the corresponding username.
min-pool-size : The starting pool size for the number of database connections to be allowed
by the application server, default=0. Note that the application server does
not open any connections until the first request for a connection, at which
time it opens this many connections. One way of forcing the connections to be
established when the application server is started is to write a simple
service that does nothing but ask for a connection.
max-pool-size : The maximum number of open connections maintained by the application server,
default=20. If the application server runs out of connections, it allocates
a new connection to fulfill that request, until it hits the maximum number of
connections. At that point it queues the requests until connections are freed.
Therefore, it is very important that applications close any connections that
they obtain.
NOTE: The max-pool-zize value must not exceed the max-connections porperty
value in MySql.
idle-timeout-minutes: The amount of time before the connection times out.
If a surplus connection is not in use for this many minutes, then that
connection is closed. Note that the number of open connections never goes
below the <min-pool-size>, default=0
blocking-timeout-
millis : The amount of time a thread waits on a connection, if all of the connections
are in use and the maximum connections have been allocated. On a timeout
the requestor will gett an exception.
track-statements : A Boolean (true/false) that has the data source monitor for unclosed
Statements or ResultSets when the connection is returned to the pool, this
is a debugging feature that should be turned off in production.
new-connection-sql : An sql statement that is executed against each new connection.
This can be used to set the connection schema, etc.
check-valid-
connection-sql : Identifies a SQL to be executed when the connection is established to
verify that the connection is valid, e.g. SELECT 1
JBoss will run the SQL statement before handing out the connection from
the pool. If the SQL fails, the connection will be destroyed/closed and
new ones will be created.
MySQLValidConnectionChecker is preferred for newer drivers. This will be run
before a managed connection is removed from the pool for use by a client.
See: valid-connection-checker-class-name
valid-connection-
checker-class-name : A class that determines if a connection is valid before it is handed out
from the pool. Should only be used on drivers after 3.22.1 with "ping"
support. The class specified must implement the
org.jboss.resource.adapter.jdbc.ValidConnectionChecker interface. Use this
option instead of check-valid-connection-sql when you want to use more than
a single SQL statement to check the validity of the connection. Be aware
that any application making a connection request that causes a connection to
be established must wait until the connection checker is finished
For MySql the class name is:
org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker
exception-sorter-
class-name : Identifies a class used to determine if an error number returned by the
database is fatal. For MySql the class name is:
org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter
type-mapping : Used by the container-managed persistence (CMP) code to identify the
database and adjust its database handling accordingly. The name use
must match one of the names in the standardjbosscmp-jdbc.xml file.
Additionally, you can add new entries to the standardjbosscmp-jdbc.xml
to customize the database interaction.
NOTE that this is used ONLY for EJB 2.1, NOT for EJB 3.
config-property: Identifies a property to pass to the java.sql.Driver when establishing a
database connection. Refer to the documentation for your JDBC driver for the
valid properties. You can provide multiple config-property entries. Valid
only for local-tx-datasource and no-tx-datasource.
xa-datasource-
property : Identifies a property to pass to the javax.sql.DataSource when establishing
a database connection. Refer to the documentation for the JDBC driver for
the valid properties. You can provide multiple xa-datasource-property
entries. Valid only for xa-datasource.
prepared-statement-
cache-size : The number of prepared statements to hold in the cache, default=0
share-prepared-
statements : If a request creates the same prepared statement more than once in a
given request, should the same prepared statement object be used. Note
that reusing the prepared statement in this case could cause the
application to get unintended results if the application requested the result
set from the first prepared statement after creating the second prepared
statement, default=false
transaction-
isolation : Specifies the java.sql.Connection transaction isolation level to use,
unspecified means use the default provided by the database.
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
Refer to your database JDBC documentation for a description of each level
and which levels your database supports.
Notes for MySql:
* Use UTF8 charset when creating the database:
CREATE DATABASE my_database CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT CHARSET utf8;
* Use InnoDb for tables
In persistence.xml add this property for hbm2ddl:
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
or if you creates the tables by writing the SQL DDL by hand (you little machocist:):
CREATE TABLE `my_database`.`my_table` (
`id` INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
`text` VARCHAR(256) NOT NULL DEFAULT '',
PRIMARY KEY (`id`)
) ENGINE = InnoDB;
MySql example:
<local-tx-datasource>
<jndi-name>seam-refimplDatasource</jndi-name>
<connection-url>jdbc:mysql://localhost/refimpl_db?characterEncoding=UTF-8</connection-url>
<driver-class>com.mysql.jdbc.Driver</driver-class>
<user-name>root</user-name>
<password></password>
<min-pool-size>20</min-pool-size>
// Make sure your MySQL config has that many max_connections!
This is the max_threads in default Tomcat server.xml on JBoss AS. //
<max-pool-size>250</max-pool-size>
<blocking-timeout-millis>5000</blocking-timeout-millis>
// Needs to be smaller than wait_timeout (which is in seconds) in /etc/my.cnf! //
<idle-timeout-minutes>2</idle-timeout-minutes>
// These are the secret ingredients that make it stable! A simple check-valid-connection-sql won't be enough! //
<exception-sorter-class-name>com.mysql.jdbc.integration.jboss.ExtendedMysqlExceptionSorter</exception-sorter-class-name>
<valid-connection-checker-class-name>com.mysql.jdbc.integration.jboss.MysqlValidConnectionChecker</valid-connection-checker-class-name>
</local-tx-datasource>
-->
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