JNDI・JDBC・JTA

dataSource:
  "jdbc/app":
    url: "jdbc:postgresql://db.example.invalid:5432/app"
    driverClass: org.postgresql.Driver
    user: app
    password: "CHANGE-ME"
    maxConnections: 8
    maxIdle: 8
    borrowTimeoutMillis: 30000
    validationQuery: "SELECT 1"
    queryLog: "off"
    connectionProperty:
      ApplicationName: kohaku-app

<resource-ref>
  <res-ref-name>jdbc/app</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
  <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

<kohaku-web xmlns="urn:kohaku:web" version="1.0">
  <data-source name="jdbc/app">
    <url>jdbc:postgresql://db.example.invalid:5432/app</url>
    <driver-class>org.postgresql.Driver</driver-class>
    <user>app</user>
    <password>CHANGE-ME</password>
    <max-connections>8</max-connections>
    <max-idle>8</max-idle>
    <borrow-timeout-millis>30000</borrow-timeout-millis>
    <validation-query>SELECT 1</validation-query>
    <connection-properties>
      <ApplicationName>kohaku-app</ApplicationName>
    </connection-properties>
  </data-source>
</kohaku-web>

javax.sql.DataSource ds = (javax.sql.DataSource)
    new javax.naming.InitialContext().lookup("java:comp/env/jdbc/app");
try (java.sql.Connection connection = ds.getConnection();
     java.sql.PreparedStatement statement = connection.prepareStatement("SELECT 1");
     java.sql.ResultSet result = statement.executeQuery()) {
    if (result.next()) {
        int value = result.getInt(1);
        // value を処理する
    }
}

javax.transaction.UserTransaction tx = (javax.transaction.UserTransaction)
    new javax.naming.InitialContext().lookup("java:comp/UserTransaction");
tx.setTransactionTimeout(30); // 秒。次のbeginに適用
tx.begin();
// この後でDataSourceから接続を取得し、SQLを実行する。
// 成功時はtx.commit()、失敗時は状態を確認してtx.rollback()。
// どちらの場合もJDBC資源を閉じる。