What are the benefits and drawbacks of using CDI in servlets with Wildfly?

1 Benefits of CDI

One of the main benefits of using CDI in servlets with Wildfly is that it simplifies the development and testing of web applications. You can use annotations to declare and inject beans, such as services, repositories, controllers, or other components, without relying on XML configuration or manual lookup. You can also use qualifiers, scopes, stereotypes, and producers to customize the behavior and availability of your beans. CDI also provides a unified event model, an interceptor framework, and a portable extension mechanism that enable you to integrate with other Java EE technologies and frameworks.

2 Drawbacks of CDI

However, using CDI in servlets with Wildfly also has some drawbacks that you should be aware of. One of them is the performance overhead of creating and managing beans and contexts. Depending on the scope and complexity of your beans, CDI may introduce some latency and memory consumption to your application. Another drawback is the learning curve and compatibility issues of CDI. You need to understand the CDI specification, its annotations, its services, and its interactions with other Java EE components. You also need to ensure that your CDI implementation, such as Weld, is compatible with your servlet container and application server version.

3 How to use CDI in servlets with Wildfly

To use CDI in servlets with Wildfly, you need to follow some steps and best practices. First, you need to add a beans.xml file to your web module, which enables CDI scanning and processing. Second, you need to annotate your servlets and beans with the appropriate CDI annotations, such as @Named, @Inject, @RequestScoped, or @SessionScoped. Third, you need to configure your Wildfly server to use Weld as the CDI provider, which is the default option since Wildfly 8. Fourth, you need to test and debug your CDI application using tools such as Arquillian, Weld Probe, or CDI Dev Mode.

4 Alternatives to CDI

If you are not convinced by the benefits of using CDI in servlets with Wildfly, or if you encounter some problems or limitations with CDI, you may consider some alternatives. One of them is using plain Java EE annotations, such as @Resource, @EJB, or @PersistenceContext, to inject resources or components into your servlets. Another option is using Spring Framework, which is a widely used dependency injection and application framework for Java. Spring offers similar features as CDI, but with more flexibility and customization options. However, you need to be careful about the integration and compatibility issues between Spring and Wildfly.

5 Tips and tricks for CDI

To make the most out of using CDI in servlets with Wildfly, you may want to follow some tips and tricks that can help you improve your productivity and performance. One of them is using CDI qualifiers to distinguish between different beans that have the same type or name. For example, you can use @Default, @Any, or custom qualifiers to inject different implementations of a service or repository. Another tip is using CDI producers to create and expose beans that are not managed by CDI, such as third-party libraries or legacy code. For example, you can use @Produces to inject a Logger or a DataSource into your beans. A third tip is using CDI events and observers to communicate between beans or modules without coupling them. For example, you can use @Observes to listen to events fired by @Fire.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?