Where to transform a result of WebService, in Repository or ViewModel?

Question

I have an application architectured by: View -> ViewModel -> Repository -> Datasource.

My DataSource is consuming a webservice and then receiving a Soap object, which I want to transform to a custom Pojo object. So, by using RxJava I am calling the DataSource method by following this flow:

ViewModel

    repository.webserviceCall(data)...
            .subscribe();

Repository

public Single<SoapObject> webserviceCall(String data) {
    return dataSource.webserviceCall(data);
}

Datasource

public Single<SoapObject> webserviceCall(String data) {
    WSSoapDAO soapDAO = new WSSoapDAO("webserviceMethodName");
    soapDAO.addProperty("data", data);
    return soapDAO.call();
}

and then I would like to know where should I transform the SoapObject received in the DataSource call, either in the Repository class, in the ViewModel class or in thee DataSource class itself?

Answer 1

In terms of your architecture I'd say the transformation should go to the repository. Let's call the entity that is to do the transformation Mapper. The mapper is supposed to transform a DTO object, SoapObject, to a model object, PojoObject.

For example

public interface Mapper {
    public PojoObject map(SoapObject dto)
}

Now the presentation layer (View and ViewModel) knows nothing about DTO objects exposed by the Datasources.