Spring 데이터 카우치베이스의 카우치베이스 트랜잭션 지원

Transaction support has been recently added to the Couchbase SDKs. Starting in Spring Data Couchbase 5.0.0-M5, support for transactions has been added to Spring 데이터 카우치베이스. In this blog, we will describe using the Spring Data @Transactional annotation to leverage Couchbase Transactions.

그리고 스프링 데이터 카우치베이스 repository contains a spring-data-testapp which exercises transactions. It relies on the 여행 샘플 bucket on a local Couchbase server. (any bucket with a primary index will suffice).

Beans supporting transaction management have been added to 추상 카우치베이스 구성. To allow the built-in transaction interceptor class to be overridden with the CouchbaseTransactionInterceptor, ensure the following line is in the application.properties file:

application.properties

The transaction configuration can be modified by overriding the configureEnvironment() method in your class which extends 추상 카우치베이스 구성.  Here we set the durabilityLevel 에 없음 so we can work in our single-node cluster.

Config.java

In the class which will use them, we need to define the template as usual and a reference to the service object. It’s important to note that the 오토와이어드 annotation  populates a variable with a proxy object. This is an important detail as the proxy objects perform processing before and after calling the actual method. Directly creating the service object from its constructor will result in the @Transactional annotation having no effect.

CmdRunner.java

The service is defined with an 서비스 annotation. The constructor takes arguments which are @Bean objects, such that the infrastructure can create a proxy object for 오토와이어드.

AirlineGateService.java

AirlineGateService.java (cont’d)

Now use everything we have constructed:

1. save two AirlineGates documents, each of which indicates 200 gates
2. verify they have been saved.
3. execute the transferGates() method of the service to transfer 50 gates from one airline to the other in a transaction.
4. verify that the transfer has taken place.
5. attempt to execute transferGates() again, this time with an exception occurring after the first document has been saved.
   
   CmdRunner.java

How it works:

• 그리고 TransactionInterceptor @Bean in 추상 카우치베이스 구성 overrides the built-in TransactionInterceptor for @Transactional annotated methods.  
• The @Transactional annotation causes the proxy for AirportGatesService 를 사용하여 TransactionInterceptor to call the annotated method using the CouchbaseCallbackTransactionManager.  
• 그리고 CouchbaseCallbackTransactionManager initializes a transaction and then calls the actual service method in the context of the transaction. 
• If the method call is successful, the CouchbaseCallbackTransactionManager commits the transaction. 
• If the commit is successful, the call returns. 
• If the commit fails with a retryable exception, the CouchbaseCallbackTransactionManger will retry the complete process of initializing a new transaction, executing the actual service method and then committing the transaction. 

그리고 CouchbaseCallbackTransactionManager will repeat this until either the commit succeeds, or the maximum number of retries has been reached.

Options for next steps

• Couchbase transactions can be leveraged in Spring 데이터 카우치베이스 by using the TransactionalOperator – see the Spring Data docs here.
• Transactions can also be directly used by the Couchbase Java SDK – see the Java ACID transaction docs here.