samplegerma.blogg.se - Domain driven design principles

#DOMAIN DRIVEN DESIGN PRINCIPLES MANUAL#
#DOMAIN DRIVEN DESIGN PRINCIPLES SOFTWARE#
#DOMAIN DRIVEN DESIGN PRINCIPLES CODE#

Data Access, where classes that are responsible for saving data to the database and load it from database live.Business Logic, where … business logic should be.Contracts, where DTOs that define data structures exchanged between UI and business logic lives.You can open a solution that contains our loan application processing service implemented this way from here.Įach layer is implemented in a separate project and deployment unit.

#DOMAIN DRIVEN DESIGN PRINCIPLES CODE#

In this approach, code is organized by layer, where each layer has different technical responsibilities. Second, people find it in tutorials from framework and platform vendors. First, it is very simple to understand and implement. There are many reasons for the popularity of this approach. This is still a very popular option and we are going to explore the typical layered app in more detail here. This is a layered architecture with an anemic domain model. We will first have a look at something that is still a very popular style of designing and implementing applications, especially among the enterprise developers. Onions have layers, ogres have layers, and guess what else have layers – enterprise apps have layers too.

The loan monthly installment must not exceed 15% of the customer’s monthly income.

The customer must not be a registered debtor in the national debtors’ registry system.

The customer age at the day of the last loan installment must not exceed 65 years.

The property value must not exceed the requested loan amount.

Let’s review the scoring rules for our application score calculation. The system validates the operator’s competence level.

If the score is GREEN then the operator validates the attached documents and accepts application or rejects it due to discrepancies between provided data and documents.

If the score is RED application is rejected and an explanation is provided.

Operator commands the system to calculate the score based on rules.

The system performs basic validation: required fields, data formats.

The operator submits loan application with property information, customer data, loan information and attached documents provided by the customer.

Let’s see how the business process looks in a more detailed manner. That’s what high-level requirements look like.

#DOMAIN DRIVEN DESIGN PRINCIPLES MANUAL#

Applications that have RED scoring results should be automatically rejected, others would require a manual check of documents sent by the customer and then approval or refusal decision should be recorded. Scoring rules should be relatively easy to add and change. To achieve this goal they want to automate application score calculation and combine information about customers from sources available online. Business wants to increase the efficiency of loan application processing for individual customers. Let’s assume that we are working for a retail bank that is selling mortgage loans. Let’s start with some business requirements.

#DOMAIN DRIVEN DESIGN PRINCIPLES SOFTWARE#

The source code for this post is located here at Altkom Software & Consulting Github. We will start with business requirements, then we will have a look at implementation that does not use domain driven design and has an anemic model, then we will analyze problems related to such approach and compare it with code build with help of domain-driven design tactical patterns. By better code I mean code that is more readable, easier to reason about and maintain. In this post, I am going to present how you can use domain-driven design tactical patterns like value object, entity, repository, domain event, factory, and domain service, to write better code.