Java – Spring Scheduling: @Scheduled vs Quartz

javaquartz-schedulerschedulingspring

I'm reading the Spring 3.0 docs regarding scheduling. I'm leaning towards Spring's JobDetailBean for Quartz. However, the @Scheduled annotation has captured my eye. It appears this is another way of scheduling task using the Spring Framework. Based on the docs, Spring provides three way of scheduling:

@Scheduled
Via Quartz
Via JDK Timer

I have no interest in the JDK Timer. Why should I choose @Scheduled over Quartz? (When I mention Quartz I mean using Spring's bean wrapper for Quartz).

Let's say my use case is complex enough that I will be communicating to a third-party web service to import and export data at specified intervals.

Best Answer

Quartz is an order of magnitude more complex than Spring's built in scheduler, including support for persistent, transactional and distributed jobs. It's a bit of a pig, though, even with Spring's API support.

If all you need to is to execute methods on a bean every X seconds, or on a cron schedule, then @Scheduled (or the various options in Spring's <task> config schema) is probably enough

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Java – What’s the difference between @Component, @Repository & @Service annotations in Spring

From Spring Documentation:

The @Repository annotation is a marker for any class that fulfils the role or stereotype of a repository (also known as Data Access Object or DAO). Among the uses of this marker is the automatic translation of exceptions, as described in Exception Translation.

Spring provides further stereotype annotations: @Component, @Service, and @Controller. @Component is a generic stereotype for any Spring-managed component. @Repository, @Service, and @Controller are specializations of @Component for more specific use cases (in the persistence, service, and presentation layers, respectively). Therefore, you can annotate your component classes with @Component, but, by annotating them with @Repository, @Service, or @Controller instead, your classes are more properly suited for processing by tools or associating with aspects.

For example, these stereotype annotations make ideal targets for pointcuts. @Repository, @Service, and @Controller can also carry additional semantics in future releases of the Spring Framework. Thus, if you are choosing between using @Component or @Service for your service layer, @Service is clearly the better choice. Similarly, as stated earlier, @Repository is already supported as a marker for automatic exception translation in your persistence layer.

Annotation	Meaning
`@Component`	generic stereotype for any Spring-managed component
`@Repository`	stereotype for persistence layer
`@Service`	stereotype for service layer
`@Controller`	stereotype for presentation layer (spring-mvc)

Java – Spring: @Component versus @Bean

@Component and @Bean do two quite different things, and shouldn't be confused.

@Component (and @Service and @Repository) are used to auto-detect and auto-configure beans using classpath scanning. There's an implicit one-to-one mapping between the annotated class and the bean (i.e. one bean per class). Control of wiring is quite limited with this approach, since it's purely declarative.

@Bean is used to explicitly declare a single bean, rather than letting Spring do it automatically as above. It decouples the declaration of the bean from the class definition, and lets you create and configure beans exactly how you choose.

To answer your question...

would it have been possible to re-use the @Component annotation instead of introducing @Bean annotation?

Sure, probably; but they chose not to, since the two are quite different. Spring's already confusing enough without muddying the waters further.

Best Answer

Related Solutions

Java – What’s the difference between @Component, @Repository & @Service annotations in Spring

Java – Spring: @Component versus @Bean

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