Oracle DB failover in Spring Boot handling

Question

I would like to create annotation based interceptor which will log the current DB details wherever primary db is failing to server the request and secondary db will start to give support for the application.

I found below code from mentioned link but I could not find the specific orcl annotation which has to be used for the annotation like @Aspect for aop in the below , Please help to find this.

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:orcl="http://www.springframework.org/schema/data/orcl"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
       http://www.springframework.org/schema/data/orcl
       http://www.springframework.org/schema/data/orcl/spring-data-orcl-1.0.xsd">

    <aop:config>
        <aop:advisor pointcut="execution(* *..PetStoreFacade.insertOrder(..))" 1 
            advice-ref="racFailoverInterceptor" order="1"/>
        <aop:advisor pointcut="execution(* *..PetStoreFacade.*(..))" 2 
            advice-ref="txAdvice"/>
    </aop:config>

    <orcl:rac-failover-interceptor id="racFailoverInterceptor"/> 3

    <tx:advice id="txAdvice">
        <tx:attributes>
            <tx:method name="insert*"/>
            <tx:method name="update*"/>
            <tx:method name="*" read-only="true"/>
        </tx:attributes>
    </tx:advice>

</beans>

https://docs.spring.io/spring-data/jdbc/old-docs/2.0.0.BUILD-SNAPSHOT/reference/html/orcl.failover.html

I'm not sure if I understood you correctly but from my point of view you can use `@ControllerAdvice` and `@ExceptionHandler` to catch exceptions which can cause database connection lost and update DataSource bean properties with new configuration in spring context. It is only my thoughts, I believe there should be better approach for this case. — Kamil W, Sep 10 '18 at 19:04

Babl · Accepted Answer · 2018-09-13T07:50:22.063

Basically, there is no out of the box "Oracle" annotation which can be used to make rac failover interceptor work. But it is easy to add new custom annotation which will do the work for you.

Provided that the sprig data oracle is at your classpath

Maven pom.xml

<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-oracle</artifactId>
    <version>1.2.1.RELEASE</version>
</dependency>

Just create an marker annotation which you want to use.

package org.example;
public @interface OracleFailover {
// just a marker annotation, no body
}

Configure an advisor for it

<aop:config>
    <aop:advisor 
       pointcut="@annotation(org.example.OracleFailover)" 
        advice-ref="racFailoverInterceptor" order="1"/>
</aop:config>

<orcl:rac-failover-interceptor id="racFailoverInterceptor"/>

And then use it on your business methods

package org.example;

@Service
public class SomeBusinessService {
    @OracleFailover
    void doSomethingWithOracle(){
        // body goes here
    }
}

And remember that the Rac Failover Interceptor should go before your transnational interceptor, that is failover will not work as expected in case failover interception is done when the transaction is already active.

`orcl` is a custom xml namespace which is automatically "imported" if you have the spring-data-oracle on your class path and the XML import is done (See upper part of the XML from your question). Also I have updated my example with the maven pom for spring-data-oracle maven import. — Babl, Sep 13 '18 at 07:52

Oracle DB failover in Spring Boot handling

1 Answers1