I am learning AOP and came to know that is useful for separation of concern, for example, logging, transaction management, security etc.
So far good to know AOP.
Now, I read about Spring transaction management in Spring framework we can have annotation #Transactional.
It is this point which is make me confused why should we use AOP in which we have to create Aspects rather than using the annotation which Spring provides.
For example:
#Transactional
public void dataAccessTrans() {
}
When Spring is already having transaction related functionality, then why should we use AOP to do transaction management?
If we use AOP, then don't we have to create Aspect and create advice which would act on the method; does't this make us to do manual work, rather than handling it by spring framework itself by its own annotations.
Can anyone help me understand this which I am not able to understand clearly.
Spring relies on AOP to implement declarative transactions.
The Spring Framework’s declarative transaction management is made
possible with Spring aspect-oriented programming (AOP), although, as
the transactional aspects code comes with the Spring Framework
distribution and may be used in a boilerplate fashion, AOP concepts do
not generally have to be understood to make effective use of this
code.
So as you use the #Transactional annotation :
#Transactional
public void dataAccessTrans() {
...
}
you use indirectly AOP.
So in the very most of cases, you never need to declare any custom aspects to handle the transaction management.
Related
I am new in spring transaction management. I have learn in hibernate there is locking concept for transaction management.
Does spring have such internal working Mechanism.
Yes there are locking concepts implemented in Spring. So if you are using Spring Data JPA you can simply use the #Lock annotation to decide on how you want to lock within your transaction. You can find further information here. In this example the Annotation is only used on the Repository interface methods, but as far as I know you can also use this on Service methods annotated with #Transactional.
I'm gradually introducing Spring Boot to a Spring JPA project. My intent was to first introduce Spring Boot, than at some later stage Spring Data, but I was not able to find any examples (nor a suitable starter) that uses Spring Boot + JPA without Spring Data.
How come? Is there any benefit of introducing Spring Boot to Spring JPA project, without Spring Data, or does it make sense only with Spring Data in place.
Any article link or example code would be helpfull and appreciated, thanks
More context
I'm working with a live project so every change introduces risk. We're discussing of moving from XML to JAVA based configuration, and I'm advocating adopting Spring Boot at a same time, but I lack persuasive selling points.
Personally, I want to include Spring Boot on all layers to boost future productivity, but I need to argue better the direct immediate benefits of using it in our Service/DAO module which is at the moment based on Spring/JPA/Hibernate with the good old manual CRUD implementations.
So I need selling points for using Spring Boot on a persistence layer, but ones that span beyond Spring Data (e.g. configuration gains, maintenance, testing...anything)
As folks have said above, there is no Spring Boot JPA. It's either Spring Boot Data JPA, or JPA on its own.
The immediate benefits that I could think of:
With Spring Data JPA you don't write the Dao layer. For all CRUD operations, the CrudRepository interface gives you all you need. When that is not enough, all you have to use is the #Query annotation to fine-tune your SQLs
Configuration by convention. For example, with Spring Boot, just having the H2 dependency in the classpath gets Spring to use the H2 in-memory database, gives you Datasource configuration and transaction management (only at the JPA repository level) by default
Ability to create micro-services. With Spring Boot, you can create micro services that can be deployed and run on a number of boxes with java -jar ...
You can enable annotation-based transaction with one simple annotation: #EnableTransactionManagement
Java configuration over XML. This advantage is not to be underestimated
A lot less code (the DAO layer) means also a lot less maintenance
The native ability to provide a RESTful API around data: https://spring.io/guides/gs/accessing-data-rest/
It all depends where your company is heading for. If they want to deliver business value faster and move towards more a DevOps operating model, then the above advantages should be enough selling points for any organisation
Spring wiht JPA (for example Hibernate) but without Spring-Data-Jpa means that you direct interact with the JPA Entity manager and. Typical you use it to implement your own DAO from it and use the #Respository annotation.
#Respository
public class UserDao {
#PersistenceContext EntityManager em;
public User findUserByLogin(Sting login) {
....
}
}
Even if there is no starter project, you could use a Spring-Data-JPA project, and implement the Repository in this old fashion style. (And then you could show how simple it become when you just write Spring-Data-JPA interfaces)
As far as I known, spring-boot means more convenient not any independent business feature.
In other words, spring-boot helps you to start, configure your application in some automatically way. But you can do that without spring-boot with your own specific configuration.
So, you are going to use spring-boot in your application means you are going to use spring-boot's auto configuration feature with your original application.
Actually, Spring JPA implemented in spring-data-jpa is what you are looking for not spring-boot. Of course, spring-boot can simplify your work dramatically.
I want to understand what is the exact meaning of term "autowiring" and AOP in Spring Framework.
From the official Spring Framework Reference:
The Spring container can autowire relationships between collaborating
beans. You can allow Spring to resolve collaborators (other beans)
automatically for your bean by inspecting the contents of the
ApplicationContext.
Which basically means you can leave it up to the Spring Framework to initialize your beans and ensure they're there when you need them. For example, lets say I have a number of Things in my app. Now, if I want to get all the Things and have them placed in a List<Thing>, in Spring (assuming I've configured it properly), I can simply use this code:
#Autowired
private List<Thing> things;
With no additional effort on my part I have the list I needed.
The question concerning Aspect Oriented Programming (AOP) as it relates to Spring would be quite a bit to put in a post. The simple explanation can be seen in the official Spring Framework Reference:
Aspect-Oriented Programming (AOP) complements Object-Oriented
Programming (OOP) by providing another way of thinking about program
structure. The key unit of modularity in OOP is the class, whereas in
AOP the unit of modularity is the aspect. Aspects enable the
modularization of concerns such as transaction management that cut
across multiple types and objects. (Such concerns are often termed
crosscutting concerns in AOP literature.)
One of the key components of Spring is the AOP framework. While the
Spring IoC container does not depend on AOP, meaning you do not need
to use AOP if you don’t want to, AOP complements Spring IoC to provide
a very capable middleware solution.
That section is very detailed and worth a read if you're interested in AOP.
Autowiring is a mechanism of resolving dependencies in Spring IoC container, as per Spring Reference. So instead of directly specifying the dependency (in XML or in Java configuration), you can depend on container itself to provide you with candidate(s). Spring itself should abort if you find more than one matching dependency (unless you are looking for a collection of beans).
I am learning Spring and am new to it, I want to skip learning the AOP and continue with learning how to work with DAO .Can I have a good understanding of DAO without even knowing the AOP?
Yes, you can. Spring AOP is not required for learning DAO. AOP is a different concept. But according to requirements, you can integrate both of them.
we have decided to use spring for declaratively transcation management in our application.We are using hibernate (Independently not spring template approach) for the persistance layer but want to use spring's power to manage transcation demarcations.
I was going though Spring refrence material to get an idea about the Transcation management,since its using AOP for managing the things.I just get an basic ideas about the pointcuts and its expressions but not a complete or deep understanding of Spring's AOP.
My question is how much one need to know about the AOP in order to use spring's Transcation managment,since what i understood is the only thing matters in the transcations is the pointcut expression.
any help/suggestion will be much appriciated
You don't need to know that much beyond pointcuts. Spring makes it relatively easy for you. A deep understanding is not required. They use Spring AOP, not AspectJ, which is more powerful and complex.