Why to use Spring not JSF (Advantages of spring over JSF)?

i don't know JSF very wel开发者_开发百科l, and i have a friend who is using only JSF and he asked me a very open question, why do you use spring not jsf ? and because of there are a lot of things about spring in my mind i wasn't able to give some straight answers so what are the advantages of spring over JSF ?

Spring and JSF are quite a different frameworks.
JSF is more of a web application framework and you can still use spring with JSF to manage the relationship and creations of the objects.

Spring is more of an entire j2ee application framework/plaform.
Spring MVC and web flow will help you to design web applications similar to JSF.
But spring with its IOC concept also brings a lot of other modules such as dependency injection, aop, DAO, ORM, integration, batch and social tools and much more.

You can also check the JSF-Spring combination - http://www.springsource.org/node/422

JSF is presentation layer, Spring business layer (roughly said), they can be used together and do not compete.

As said before, JSF is a request-driven, MVC web-framework, built around a light-weight IoC container and is designed to simplify and standardize the way UI-layer of a web-application is built.

Spring, on the other hand, is less concerned with UI-layer but its precise definition is hard to formulate. It can be said that the primary function of SF is to tie together different layers of a web application in a standardized way, at the same time abstracting away the implementation details of a particular web technology from the developer. As one of the consequences, the developer is freed from implementing "plumbing" and instead gets working module interconnections which are tested, implemented and used relatively easily. This should provide a boost to productivity and shortens development cycle.

This abstraction can be viewed through various Spring modules - Spring is heavily modularized, so you choose which components of the framework will you be using. Though it features a MVC framework (SpringMVC is mostly written as a reaction to the Jakarta Struts, whom the Spring developers deemed poorly written), Spring lacks a dedicated presentation module so you're free to use most of existing UI technologies (e.g. JSF, GWT-oids, etc.) - once you properly configure them in Spring.

In another words, the "scopes" of JSF and Spring are quite different (though not totally disjunct).