Hi Eric et 3D Gurus,

We are  attempting J  to use Domain Driven Design for our banking application, my module mainly pertains to loans.

I would be extremely grateful if you can clarify the following doubts I had with respect to 3D based on that fantastic book.

General DDD Queries

1)      Should creation of object be given to repository, I mean, internally the repository will obviously  call factory for a NEW object ,or should we just deal with a factory and use the repository for inserts/updates/deletes? (should a repository call the factory for additions?)

Anti – Corruption and Enterprise Segment

2)      My Banking subsystems have various domains, like Term Deposits , Loans, Global Domain etc, Is there any point in using an Enterprise Segment and an Anti Corruption Layer?

Example: My Domain (Loans) also needs Objects like “Branch” which belong to the Global Banking Domain , to validate the branch code, hence I created a bank object in my domain(loans) using a Branch Adapter,

BranchExistsSpecificationFactory ->  BranchExistsSpecification.isSatisfiedBy()

BranchExistsSpecificationFactory – uses BranchAdapter  to fetch a Branch Entity

Now should the branch adapter directly speak to Global Domain to obtain the Branch Information, I essentially have one services LoanAccountCreationService?

Or Should We accept a Enterprise Segment in our Loan Account Creation Service with contains all the information needed by all my adapters, then creation of adapter actually then does not make sense since the I can create a Branch Entity from the Enterprise Segment.

3)      Who decides the Structure of an Enterprise Segment ? My Domain or An Application calling Services of my Domain?

Specifications

4)      The same example of Loan Account Opening, I have two kinds of Specifications

-          Business Policies Specifications – These should be configurable for different implementations eg Spec A and Spec B in SITE 1 and Spec A only in SITE 2

-          System Constraints Specifications – These are Mandatory for all SITES, so that loans processing henceforth has no problems.

Have devised the following

ISpecification implemended by AbstractSpecification

MaturityDateSpecificationFactory creates  MaturityDateSpecification  using LoanProductRepository(has details of specs) , hence MaturityDateSpecificationFactory refers to a repository to build its specification.

LoanAccount is passed to MaturityDateSpecification.isStisfiedBy(loanAccount) to be validated.

LoanAccountOpeningSpecification Calls MaturityDateSpecificationFactory which inturn creates MaturityDateSpecification.

LoanAccountOpeningSpecificationFactory creates  LoanAccountOpeningSpecification which infact loops through all such specifications

My Query here is, is this fine? Or have I erred in something?

Secondly, what is  the best way to implement Business Policies Specifications, which may be optional in some sites, since I am anyway using a factory  (LoanAccountOpeningSpecificationFactory) to create LoanAccountOpeningSpecification, maybe the factory can read from a property file I call only certain specifications, but how do I depict this in my model to a business analyst?

Thirdly,  Should System Constraints Specifications (Mandatory for all SITES) be hardcoded in LoanAccountOpeningSpecification?

5)      I have certain validations that need to remain during the lifetime of an Entity object,

Example: my loan balance should never go below the min balance indicated in the loan product.

So how do I implement this Specification in my Loan Account Entity? Should I make a separate MinBalanceSpecification? Should I call that specification in my Loan Account in all its Methods ?

Thanks & Regards

Ashley

Ashley Fernandes

Consultant | Banking Products Division | Goregaon Annex, Mumbai

Direct: +91 22 6718 7421| Mobile: +91 9820842428

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