jboss-as7-mysql-ds.xml is part of the standalone.xml in which the MySQL datasource is defined. module.xml is the XML file necessary for configuring the MySQL connector module for JBoss AS 7.1.1. This file needs to be stored in $JBOSS_HOME/modules/com/mysql/main along with mysql-connector-java-5.1.25.jar.

jboss-as7-mysql-ds.xml

<subsystem xmlns="urn:jboss:domain:datasources:1.0">
  <datasources>
    <datasource jndi-name="java:jboss/datasources/MySQLDS" pool-name="MySQLDS" enabled="true">
      <connection-url>jdbc:mysql://*hostname*:3306/*dbname*?characterEncoding=UTF-8</connection-url>
      <driver>com.mysql</driver>
      <transaction-isolation>TRANSACTION_READ_COMMITTED</transaction-isolation>
      <pool>
        <min-pool-size>2</min-pool-size>
        <max-pool-size>10</max-pool-size>
        <prefill>true</prefill>
      </pool>
      <security>
        <user-name>*username*</user-name>
        <password>*password*</password>
      </security>
      <validation>
        <check-valid-connection-sql>select 1</check-valid-connection-sql>
      </validation>
      <statement>
        <prepared-statement-cache-size>32</prepared-statement-cache-size>
        <share-prepared-statements>true</share-prepared-statements>
      </statement>
    </datasource>
    <drivers>
      <driver name="com.mysql" module="com.mysql">
        <xa-datasource-class>com.mysql.jdbc.jdbc2.optional.MysqlXADataSource</xa-datasource-class>
      </driver>
    </drivers>
  </datasources>
</subsystem>

module.xml

<?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.1" name="com.mysql">
  <resources>
    <resource-root path="mysql-connector-java-5.1.25.jar"/>
  </resources>
  <dependencies>
    <module name="javax.api"/>
  </dependencies>
</module>