VO's + DAO's implementation or only Entity model [ With Pojo's and entitymanager ]

Hi,
I am designing a web application where i need to consider between below two approaches, Any help in suggesting which one is better for a scalable application.

Approach 1: Using VO's [Pojo layer] ---> DAO's[Data access layer] ----> service layer

Approach2: Using Entity model [ Pojos and Data access layer are merged into a single layer] ----> Service layer
In this approach i use entitymanager and annotations

Thanks in advance,
Bhargav

IMHO adding the DAO layer is always a good choice. Even for very small projects.

I agree to that,
But don't you think, now most of the DAO logic is being abstracted by Spring.
And having one more layer wouldn't fetch me anything there.
Instead if i take out the layer it may increase the processing speed, less objects.

:confused:

Quote:

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Originally Posted by bhargav

I agree to that,
But don't you think, now most of the DAO logic is being abstracted by Spring.
And having one more layer wouldn't fetch me anything there.

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I would use a DAO just to keep the persistence logic separated from the rest of the app. This way it could be advised differently, monitored separately, changed, etc.

Quote:

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Originally Posted by bhargav

Instead if i take out the layer it may increase the processing speed, less objects.

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That depends on how many and how large the DAOs are. I have worked on spring projects that have hundreds of DAOs with dozens of methods each and the applications ran just fine.