I would like to ask a question about the spring cache annotation and repository creation.
I am trying to cache my values in redis using the Spring boot.
(I have a value, if it is not in cache, I need to cache it, if it is in cache, I need to get it from there)
I have seen a couple of tutorials on line, some using the cache annotations and others simulating the cache repository. (maybe they do not exclude each other, this is my question about)
Here are some of the tutorials that I have read:
Cache annotation tips
Caching Data using Redis
Intro to Redis with Spring Boot
Spring Boot Redis cache
Some of the above use the #Cacheable, #CachePut and #CacheEvict annotations:
#CachePut(value = 'user', key = "#id")
#CacheEvict(value = 'user', key = "#id")
and prefix the supposed-to-be-stored class with the following annotation:
#RedisHash("balance")
They also extend the JPA or CrudRepository. The 3rd one one, however, creates its own repository.
My question is:
If I used the above annotations (#Cacheable, #CachePut and #CacheEvict) should I create a repository for the class objects I am interested in storing by extending the CrudRepository?
Or does spring create it automatically when using the above annotation and manage it automatically?
An if you extend the CrudRepository yourself, how would you retrieve the items by key from Redis?
Thanks
No this is not needed. Notice that the third link does not mention caching up front. There are two projects , spring cache with a redis cache provider and spring data redis. The third link is talking about the larger and more general use case. Spring data redis is meant to support redis as a full fledged persistence layer. However you are certainly free to only use redis as a caching layer. In this case you do not need to do anything nor should you besides using the normal annotations
Related
Is it enough and Hibernate checks methods automatically that are doing stuff with that entity and updates the cache?
Or #Cacheable, #CachePut, #CacheEvict annotations above methods are mandatory for a working cache.
What is cached depends on the configuration. If you enable selective caching, you need to annotate all entities with #Cacheable that should be cached. For queries, you additionally need to provide a cache hint, but all of that can be read in the official documentation: https://docs.jboss.org/hibernate/orm/5.5/userguide/html_single/Hibernate_User_Guide.html#caching
We are currently using Spring 3.2.3 + JPA (Hibernate). We use aspects for transaction support as opposed to annotations. We write out own entity services (read: repositories) to abstract the persistence away from our application.
I've read a lot about Spring Data and feel it would make our code considerably cleaner and more robust. I wonder though, are there any gotchas that I should consider before transitioning?
Thanks
If you're already on JPA the transition should be as easy as it can be: activate the repositories, point the infrastructure to your EntityManagerFactoryBean and off you go.
Transactions should just work fine as well. The annotation based usage within Spring Data is selectively activated for the repository beans only. They are configured to take part in existing transactions by default, so any custom larger scoped transaction setting should be in effect already.
I have a project that supports 10's of concurrent users.
My project is a spring + hibernate project with a MYSQL DB.
I would like to keep a cache for some of my entities (i.e. Player)
I have a couple of questions:
1) how do I exactly work with a cache (when i have one) ? if i have to persist a Player do i change the cache and immediately persist with hibernate?
2) Does spring support a cache mechanism ? if so how does one work with it?
Hibernate
Hibernate has Second level cache. To start work with you need to:
choose some cache provider (EHCache, Infinispan, ...).
configure cache region (and choose corresponding strategy depending on your situation)
enable cache for some entity
It is declarative, most of the time you do not need to change any application code.
Spring
Spring has cache abstraction. There are some common steps (choose chache provider, configure cache regions). But it is more general pourpose cache, not related to Hibernate entities and transactions. So you must do more work (annotate all necessary methods with annotations).
In general if your Player class is a Hibernate entity then it will be better to go with Hibernate cache. It may be not true if you have some special demands.
Hope it helps.
I have a requirement to cache an object that can't be serialized. I am looking for some methodology to cache these kind of objects via a Wrapper. Can it be done?
The objects you want to cache need not to be serialized, but of course the keys you generate to store your corresponding objects must be serialized.
Caching Example with Spring Annotations and Ehcache
Making things #Cacheable
ehcache-spring-annotations (Using Cacheable)
ehcache-spring-annotations (Frequently Asked Questions)
I am planning to implement the Cache in the web application.
I have already used the Hibernate EHCache in one of my previous web application.
Now a days, recently i came to know that in latest Spring release there is Cache Abstraction layer.
Hence i would like to is it just wrapper of Hibernate EHCache or it is Cache features provided by Spring itself.
If different then would like to know which is best or better option to use Cache ?
Also, i came to know from few articles that Hibernate EHCache not supporting clustering, is it ? Because clustering required for big Web Application.
I have used Spring 3.1 and Hibernate 3.3 in Web Application.
Hibernate and EHCache are different things.
EHCache is the cache provider, i.e. the actual implementation of the cache.
Hibernate can use multiple different providers for the L2 cache, including EHCache.
Spring Cache is a framework for caching method calls. It can use multiple different providers, including EHCache.
EHCache offers distribution (clustering) in several modes, from basic JMS-driven synchronization to Terracotta BigMemory distribution. Hibernate L2 cache should support clustering.
Spring Cache has nothing to do with Hibernate, but you can use Hibernate L2 cache and Spring Cache (method caching) in parallel with EHCache as the underlying provider for both.
Just to add, for database-level caching using hibernate, hibernate/JPA second-level cache seems more appropriate. Because it manages data caching at entity level at the persistence context level (JPA APIs), so there are very fewer chances of inconsistency in database and cache, since hibernate manages it well.
But if we use spring cache for database caching, then we always have to ensure every method operating on database need to be annotated with appropriate cache annotation (For example, #CacheEvict for remove), so there are chances of missing annotations and causing inconsistency.
Also, spring cache can only be used on public methods, since it backed my AOP (We can use AspectJ though to solve this).
Hibernate caching continues to work with Spring using EhCache (or another caching provider). It offers a 2nd level cache for storing em.find(key) entities and relationships (#Cache annotations or XML), as well as query caching if you q.setHint("org.hibernate.cacheable",true). These are integrated and well-documented. Spring caching is not needed for this.
But Spring provides method caching which is independent of Hibernate caching, and can still use EhCache as the caching provider (sharing EhCache with Hibernate). This can be a little confusing because the EhCache configurations are overlapping, but essentially Spring Caching allows you to independently cache the results of methods that are marked as #Cacheable.
Note 1: Spring/Method caching is not integrated with Hibernate. Results cached with method caching are not recognized or maintained by Hibernate.
Note 2: Hibernate Query caching is not recommended for highly distributed systems without a good understanding of how the caching is used. It increases the risk of deadlocks due to the use of a shared entity timestamp cache that Hibernate maintains to keep track of when the cached query results should be evicted.