Controller layer "between" Resources and DAO

[Fredrik Hörte]

Hi,

I just started with dropwizard (awesome btw) from Spring and I wonder what a suggested approach is for having a controller layer between the resource classes and the dao classes.

For example if I have:

FooResource
FooDAO
BarDAO

I want to be able to have a FooBarController which uses both FooDAO and BarDAO. FooResource doesn't use FooDAO or BarDAO directly but thru FooBarController. Do you have any such examples or use case you could suggest?


Thanks in advance!

[Adam Kaplan]

This seems to be more of a Jersey question than a Dropwizard question.  What you can do is pass the FooBarController (or your 'environment' if you're using DI) to the Resource constructor.

Here is some overly simplified example code in which I pass a controller to a resource during initialization. It's in Scala, but straightforward.

Service:

override def onInitialize(configuration: ServiceConfiguration, environment: Environment) {

  environment.addResource(new Resource(controller)

  ...

}

Resource:

@Path("/")

@Produces(Array(MediaType.APPLICATION_JSON))

protected class Resource(val registry:Controller) {

   ....

}

[Fredrik Hörte]

Thanks Adam,

and then I guess you are passing in your DAO in your Controller when initializing it?

Something like this?

environment.addResource(new Resource(new Controller(new DAO()))

[James Ladd]

Not specifically about a DAO but an Architectural approach that I am
using and works well
for me is the following:

1. I have an Application POJO that models my Application/System.
The methods it exposes are what the application can do.
For example:
Application app ....
app.addCustomer(customer);

2. The Interfaces to the Application are separate and essentially
marshal requests
and responses to and from the Application.

Example interfaces are: Command Line and REST

3. REST access to the Application is provided by Dropwizard (which is
excellent).
This Interface marshals documents (in JSON/+links) between the
client and the server which
result in interactions with the Application (POJO).

For example, when a POST is made with JSON containing new customer
details this Dropwizard layer marshals the JSON into a Customer
object and then
calls the Application.addCustomer() method.

The REST layer is responsible for providing a discoverable and
navigate-able document
structure that represents an allowable interaction state with the
Application.

4. This loose coupling / separation / anti-corruption layer means that
the concerns of interfacing
with the Application are not part of the Application. This enables
the addition of new Interfaces
more easily.

For example, a message queue could be added to marshal request/
response objects to and from
the Application without changing the Application POJO or domain
objects underneath it.

In coming full circle back to the Controller/DAO question, I have
domain objects within my Application
POJO that control facets of the application. You might call these
Controllers. I don't.
The Domain objects have Repository objects that represent a Store
(persistent or otherwise).

- James.

On Aug 2, 4:24 am, Fredrik Hörte <fredrikho...@gmail.com> wrote:
> Thanks Adam,
>
> and then I guess you are passing in your DAO in your Controller when
> initializing it?
>
> Something like this?
>
> environment.addResource(new Resource(new Controller(new DAO()))
>
>
>
>
>
>
>
> On Tuesday, July 31, 2012 10:09:34 PM UTC+2, Adam Kaplan wrote:
>
> > This seems to be more of a Jersey question than a Dropwizard question.
> >  What you can do is pass the FooBarController (or your 'environment' if
> > you're using DI) to the Resource constructor.
>
> > Here is some overly simplified example code in which I pass a controller
> > to a resource during initialization. It's in Scala, but straightforward.
>
> > Service:
> > override def onInitialize(configuration: ServiceConfiguration,
> > environment: Environment) {
> >   environment.addResource(new Resource(controller)
> >   ...
> > }
>
> > Resource:
> > @Path("/")
> > @Produces(Array(MediaType.APPLICATION_JSON))
> > protected class Resource(val registry:Controller) {
> >    ....
> > }
>
> > On Tuesday, July 31, 2012 1:41:51 PM UTC-4, Fredrik Hörte wrote:
>
> >> Hi,
>

> >> I just started with dropwizard (*awesome btw*) from Spring and I wonder