I have two micro services A B, In service A, call service B through restTemplate, and service B does some persistence job, like insert data into db.
Here is my question: what if service B execute successfully, data are saved into db, but timeout happen when service B response, so service A‘s API response fails, but data are actually inserted into db, how to rollback transaction?
Sqmple code:
#Service
public class ServiceA {
#Autowired
private RestTemplate restTemplate;
#RequestMapping("/user/save")
public User saveUser(){
ResponseEntity<User> entity = restTemplate.getForEntity("http://{serviceBHost}/insertData", User.class);
return entity.getBody();
}
}
#Service
public class ServiceB {
#AutoWired
UserMapper userMapper;
public User saveUser(User u) {
User result = userMapper.insert(u);
return result;
}
}
process flow
Its not recommended to have distributed transaction in microservice based architecture. It should be avoided as much as possible.
Nevertheless, below article may be helpful to you.
https://walkingtreetech.medium.com/transaction-management-in-microservices-ab09b0cb803b
Related
I have a bean that is annotated with #KafkaListener and inside this bean, I am planning to get the logged-in user credentials through SecurityContextHolder.
However, SecurityContextHolder.getContext().getAuthentication() is giving me a null object probably because this is running in a different thread.
In this case, is there a way to propagate the SecurityContext from ThreadLocal to another thread? Can it easily be done in my Spring Boot configuration?
Below is the sample code:
#Component
#Slf4j
public class MessageConsumer {
private final MessageService messageService;
#Autowired
public MessageConsumer(final MessageService service) {
messageService = service;
}
#KafkaListener(topics = "myTopic")
public void receive(final List<Message> message) {
messageService.consumerAnStoreMessage(message, SecurityContextHolder.getContext().getAuthentication());
}
}
The SecurityContext's authentication represents, for exemple, a user who called a webservice, a website's page... etc...
When you listen to a kafka message, which user's context should be used ?
I don't think what you are trying to do really makes sens.
I am building ReSTful APIs using Spring-boot 1.5.10.RELEASE, Java 8 and MySQL 5.6 and jOOQ(https://www.jooq.org/doc/3.9/manual/). In Service layer, I am using #Transactional annotation offered by Spring framework.
Here is how my UserService class looks like:
#Service
#Slf4j
public class UserService {
//My repository isn't using #Transactional annotation, only Service layer
#Autowired
private UserRepository userRepository;
#Transactional
public User createUser(User user){
...
}
#Transactional
public User updateUser(User user){
...
}
#Transactional
public Boolean deleteUser(Integer userId){
...
}
#Transactional(readOnly = true)
public User findUserByUserId(Integer userId){
...
}
}
Shall I use #Transactional(readOnly=true) or not use #Transactional annotation at all for HTTP GET API calls?
Are there any side effects I should be aware of when not using #Transactional on all CRUD operations above?
Do I have to make jOOQ aware of Transactional capabilities by offering configuration?
I have not used #Transactional from Spring framework in past but do understand what transactions are and why we need them.
I hope I didn't miss any details in question :)
I have a very basic Spring Boot/JPA stack app, with a controller, service layer, and repository that does not persist updates as I understand it should.
A trivial Entity:
#Entity
public class Customer {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String name;
protected Customer() {}
public Customer(String name) { this.name = name; }
// standard getters,setters //
}
A trivial Repository:
#Repository
public interface CustomerRepository extends CrudRepository<Customer, Long> {}
A simple Service layer:
// If the service is #Transactional and the controller is not, the update does NOT occur
#Transactional
#Service
public class CustomerService {
private static final Logger LOG = getLogger(CustomerService.class);
#Autowired
private CustomerRepository customerRepository;
boolean updateCustomerName(Long id, String name) {
Customer customer = customerRepository.findOne(id);
if (customer == null) { return false; }
// Modifies the entity
customer.setName(name);
// No explicit save()
return true;
}
}
And a REST controller that uses it all:
// If the controller is #Transactional and the service is not, the update occurs
#RestController
#RequestMapping("/mvc")
public class CustomerController {
#Autowired
private CustomerService customerService;
#RequestMapping(path = "{id}", method = RequestMethod.PUT)
public ResponseEntity updateCustomerName(#PathVariable Long id, #RequestParam("name") String name) {
customerService.updateCustomerName(id,name);
return ResponseEntity.noContent().build();
}
}
These are wired together with a simple one-liner SpringBootApplication
I have SQL debug logs enabled and see the selects, update, etc.
With the code above: When the service method is invoked by the controller, the modified entity is not persisted. SQL logs show the select of the entity but no update.
There is also no update if nothing is marked #Transactional
However, simply by moving the #Transactional annotation from the service class to the controller class, the SQL update does occur.
If I add an explicit customerRepository.save(customer) to the service method, the update also occurs. But my understanding is that the ORM should automatically save modified persistent entities.
I'm sure the issue has something to do with the EntityManager lifecycle in the web request, but I'm puzzled. Do I need to do additional configuration?
Complete example at https://github.com/monztech/SO-41515160
EDIT: This was solved, see below. Per the Spring spec #Transactional does not work in package-private methods and mistakenly did not make the update service method public.
The update will occur if the method is public and the service class has the #Transactional annotation.
I do have another question, however. Why is the #Transactional annotation necessary? (the update does not occur without it) Shouldn't the entity manager still persist the object because of the open session in view mechanism that Spring uses, independent of any transaction?
Make your updateCustomerName method public.
I'm not fully understanding when to use #SessionAttributes vs #Scope("session") beans.
Currently, I'm doing the following
#ControllerAdvice(assignableTypes = {DashboardController.class, FindingWholeSalersController.class})
public class AuthControllerAdvice {
private IFindWholeSalerService service;
public IFindWholeSalerService getService() {
return service;
}
#Autowired
public void setService(IFindWholeSalerService service) {
this.service = service;
}
//put firstname in session etc..
#ModelAttribute
public void addWholesalerDiscoveryCountToSession(Model model, Principal principal){
if (!model.containsAttribute("firstname")) {
String firstname = service
.findUserFirstName(principal.getName());
model.addAttribute("firstname",
firstname);
}
}
Notice this if test if (!model.containsAttribute("firstname"))
Basically, if the session attribute is already in the model, then I dont want to ask my service layer to make a database request. However, every #RequestMapping call in any of the controllers I'm advising, first makes a call to
#ModelAttribute
public void addWholesalerDiscoveryCountToSession(Model model, Principal principal)
Does the if test, and moves on its marry way.
Is this the right solution for keeping data in the session so you dont have to call your database, OR would #Scope("session") beans be a better choice OR something else?
Thanks for all advice in advance!
I have rest style controller in Spring. In controller I have injected dao interfaces. From controller I persist data. In the other words, I have like REST web service. people sends me data, and I persits it.
/**
* Payment rest controller which receives
* JSON of data
*/
#Controller
#RequestMapping("/data")
public class PaymentTransaction {
#Autowired
private TestDao dao;
#RequestMapping(value = "/test", method = RequestMethod.POST)
#ResponseBody()
public String test(HttpServletRequest request) {
...
}
At the moment I have #transaction annotation in Dao classes. For instance:
import org.springframework.transaction.annotation.Transactional;
#Component
#Transactional
public interface TestDao {
#Transactional(propagation = Propagation.REQUIRED)
public void first();
}
I have read that this is very bad style. Using this answer at stackoverflow , here is explain and examples why is this bad - we must not add this annotation in DAO and in controller too. We must add it in service layer.
But I don't understand what is the service layer? Or where is it? I do not have anything like this.
where should I write #Transactional annotation?
Best regards,
According to the cited post, you should design your classes somehow like this (rather pseudocode):
controller (responsible for handling clients' requests/responses)
#Controller
#RequestMapping("/data")
public class TestREST {
#Autowired
private TestService service;
public void storePayment(PaymentDTO dto) {
service.storePayment(dto); //request from a client
}
public PaymentDTO getPayment(int paymentId) {
return service.getPayment(paymentId); //response to a client
}
}
service layer (also called business layer, responsible for business logic - knows what to do with incoming messages, but does not know where they come from).
public class TestServiceImpl {
#Autowired
private TestDao dao;
#Transactional(propagation=Propagation.REQUIRED) //force transaction
public void storePayment(PaymentDTO paymentDto) {
// transform dto -> entity
dao.storePayment(paymentEntity); //read-write hence transaction is on
}
#Transactional(propagation=Propagation.NOT_SUPPORTED) //avoid transaction
public Payment getPayment(int paymentId) {
return dao.findPayment(paymentId); //read-only hence no transaction
}
}
data access layer (also called persistence layer, responsible for accessing database - knows how to use entity model / ORM, does not know anything about the upper service layer)
public class TestDAOImpl {
#PersistenceContext
private EntityManager em;
public void storePayment(PaymentEntity paymentEntity) {
em.persist(paymentEntity);
}
public PaymentEntity getPayment(int paymentId) {
return em.find(PaymentEntity.class, paymentId);
}
}
By this approach you get separation of concerns mentioned in the post. From the other hand such an approach (business layer vs data access layer) got a little dose of criticism from Adam Bien's on his blog ("JPA/EJB3 killed the DAO"). As you can see there is no a single solution for the problem, but I encourage to read some other opinions and apply the solution you find the most suitable for your needs.
When you call two Dao methods first & second from controller, 2 transactions will be done, one with starts before first method and ends after it's execution and the second one starts before second method starts and ends after it's execution. Whereas you create an additional class in between controller and dao (usually this is called service layer) and annotate it with #Transactional and call multiple Dao methods in it, a transaction is started at the start of service method and all the dao calls will be executed and transaction will be closed, which is what you require. And inject the Service into Controller.
Controller -> Service -> Dao
#Controller
#RequestMapping("/data")
public class PaymentTransaction {
#Autowired
private TestService service;
#RequestMapping(value = "/test", method = RequestMethod.POST)
#ResponseBody()
public String test(HttpServletRequest request) {
...
}
}
#Service
#Transactional
public class TestService {
#Autowired
private TestDao dao;
#Transactional
public void serviceCall(){
dao.first();
dao.second();
}
}