Spring and EJBs

[Mark Garland]

Hi Craig,

I am studying towards SCBCD, learning for the first time all about EJBs and the new JPA architecture.

I've always seen Spring as something that was written to circumvent the deficiencies in EJB2.x, and now EJB3 has been released I would imagine that the need for Spring is lesser?
A colleague points out that Spring also manages the frontend/web aspect, which EJB3 doesn't (as it is for the business layer), however I would imagine that by using something light like struts, JSF or some other framework you could achieve the same things?
I'm sure I've also read somewhere that Spring is great for smaller projects but isn't as scalable as EJBs etc. which gives me concern over using it for large business systems.

My questions would be
- Where does Spring fit? Does it still have relevance? What can Spring do better than an EJB and Web framework combination?
- Is Spring as Enterprise level as EJBs, especially in terms of clustering and scalability?

Thanks,

MG

[Anil Vupputuri]

Mark Garland wrote:
- Where does Spring fit? Does it still have relevance? What can Spring do better than an EJB and Web framework combination?
- Is Spring as Enterprise level as EJBs, especially in terms of clustering and scalability?

Very good information and answers can be found at webpage

[Alaa Nassef]

Well, I think that this article is a little outdated (June 2005). Anyway, spring's main advantages are

Doesn't need a container

Integrates with lots of technologies easily

Simplifies a lot of APIs when integrating with other technologies (mail for example)

However, EJB 3.1 has a light version that doesn't need a container. Finally, Spring is great with Aspect Oriented Programming (AOP). Don't know if EJB has that.

[Jeanne Boyarsky]

Spring is still ahead of EJB. For example, Spring does dependency injection anywhere and of any interface. J2EE only allows it in session beans, MDBs and Servlets. And even then only certain types of resources. Similarly for AOP. EJB has interceptors; Spring has AOP anywhere.

I think it is true that EJB has an advantage in scalability, but only in specific scenarios. If you are doing relying on your EJB layer to go to different servers to handle load and scalability, EJB is designed for this. However, most people don't use this feature and handle load balancing at the servlet or messaging layer instead.

[Mark Garland]

Hi Anil, Alaa and Jeanne,

Thank you for your replies.

The idea of being able to run without a container is certainly appealing as they can often be quite slow (especially if the machine has limited hardware).

The idea of handling scalability at the messaging layer is a great idea that I hadn't really considered and I guess that this would easily circumvent the need for complex clustering on the side of the container. I guess though that this wouldn't work so well for SFSBs, however I am not sure how often these are actually used in practice due to their poor performance reputation from early containers; and I also suppose that if the interaction is web-based, the HTTPSession could be used here instead.

A very interesting discussion - thank you for your inputs!

MG