Question

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should you do validation at the service layer, even if you validate at the front-end?

eg struts has validations so you can validate it a lot. (I don’t mean java script validations.)

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are you using hibernate validator or spring validations in your service layer even though you have validations already on front-end?

(front-end validation don’t have to be hibernate or spring one)

Answer 1

Consistent Data are one of the most important thing in Enterprice Applications!

So yes: you need to check it twice: in the frontend and in the Service layer.

In our web applications we have different checks at different levels:
(I am not talking about inconsistent checks, I am talking about granularity and scope of checks.)

1. Java Script checks of inputfields (max length, not empty …)
2. The same checks like (1) and some more complex checks in the Server side web controller
3. The important (and sometimes complex) constraints which would break the application logic are checked in the entities and services
4. Everything a database can check easily (not null, forein key, unique) are checked by the database constraints.

IHO it would be the best to check all and everywhere, but this is not possible. So you need a consistent policy where you check what. And this policy strongly depends on the kind of application your are developing.