domain driven design talk
1 like472 views
1. The document discusses architectural concepts for building a REST application including entities, value objects, aggregates, repositories, factories, and separating the application into layers including presentation, domain, and infrastructure. 2. It provides examples of caching at each layer to reduce data formatting time and database hits. 3. Guidelines are given for structuring the codebase with modules for each domain model and separating layers into directories for each concern.
![Cache-Presentation
GET /orders/{orderId}
order_json = cache.get(“/order/#{orderId}”)
if order_json?
order_response = app.get_order_by_id(orderId)
cache.set(“/order/#{orderId}”, convert_to_json(order_response))
{
“userId”: “123abc”,
“id”: “order001”,
“lineItems”: […], #two line items
“address”: {…}
}
POST /orders/{orderId}/lineitems/ #add a new item to the order
{
“id”: “order001”,
“phoneItemIds”: [“e5ab0134b”]
}
order = app.add_line_items(“order001”, “e5ab0134b”)
cache.set(“/order/#{orderId}”, to_json(order))](https://image.slidesharecdn.com/domaindrivendesigntalk-150419223905-conversion-gate01/85/domain-driven-design-talk-8-320.jpg)
domain driven design talk
- 1. Presentation REST Application (thin and no biz logic!) Server API Client Domain (core, biz logic) Factory Repository Entity/VO Aggregate Infrastructure Persistence Push, Mail … Report, Print… CLI HTML
- 2. Entity • An object is distinguished by its identity. • Aggregate root must be an entity. • Eg: PhoneItem, User, Order, LineItem
- 3. Value Object • No identity. • Only care about attributes • Immutable. • Eg: UserProfile, OrderAddress
- 5. Aggregate
- 6. Get Order By Id
- 7. Caching • Presentation Layer Reduce data format conversion time • Service (App Layer/Domain Layer) Reduce multiple infrastructure layer cache hits • Infrastructure Reduce hits on actual persistence service (eg: MySQL)
- 8. Cache-Presentation GET /orders/{orderId} order_json = cache.get(“/order/#{orderId}”) if order_json? order_response = app.get_order_by_id(orderId) cache.set(“/order/#{orderId}”, convert_to_json(order_response)) { “userId”: “123abc”, “id”: “order001”, “lineItems”: […], #two line items “address”: {…} } POST /orders/{orderId}/lineitems/ #add a new item to the order { “id”: “order001”, “phoneItemIds”: [“e5ab0134b”] } order = app.add_line_items(“order001”, “e5ab0134b”) cache.set(“/order/#{orderId}”, to_json(order))
- 9. Cache-Service app.get_order_by_id(id) order_response = cache.get(“get_order_by_id_#{id}”) if order_response.nil? order = order_repository.find_by_id(id) #convert order to order_response cache.set(“get_order_by_id_#{id}”, order_response) return order_response app.app.add_line_items(order_id, phone_item_id) order = order_repository.find_by_id(id) phone_item = phone_item_repository.find_by_id(phone_item_id) order_item = order.add_line_item(phone_item) order = order_repository.store(order) #convert order to order_response cache.set(“get_order_by_id_#{id}”, order_response) return order_response
- 10. Cache-Infrastructure order_access.select_by_id(id) data = cache.get(“select_order_data_by_id_#{id}”) if data.nil? #retrieve from persistence media (eg: mysql) cache.set(“select_order_data_by_id_#{id}”, data) lineitem_access.select_by_order_id(id) data = cache.get(“select_lineitem_data_by_order_id_#{id}”) if data.nil? #retrieve from persistence media (eg: mysql) cache.set(“select_lineitem_data_by_order_id_#{id}”, data) lineitem_access.insert(line_item_data) #insert line_item_data into persistence media (eg: mysql) cache.clean(“select_lineitem_data_by_order_id_#{line_item_data.order_id}”)
- 11. Model vs Module • Domain model is inventory. • Ordering is sub domain model • User, PhoneItem and Order are modules in ordering domain model.
- 12. File Structure lib/ inventory_app.rb order_response.rb lineitem_response.rb inventory_app_server.rb … domain/ <——— domain layer phone_item/ phone_item.rb phone_item_factory.rb phone_item_repository.rb order/ order.rb lineitem.rb order_factory.rb order_repository.rb services/ <services>.rb base/ <——— infrastructure layer order_access.rb lineitem_access.rb order_data lineitem_data.rb … some_service_interface.rb persist/ mysql/ <access implementation>.rb some_service_interface/ views/ <——— presentation layer