Domain-Driven Data at SunshinePHP

There are many types of databases and data analysis tools from which to choose today. Should you use a relational database? How about a key-value store? Maybe a document database? Or is a graph database the right fit for your project? What about polyglot persistence? Help! Applying principles from Domain-Driven Design such as strategic design and bounded contexts, this session will help you choose and apply the right data layer for your application's model or models. We'll explore traditional relational databases, graph databases, document databases, key/value stores, polyglot persistence, CQRS, event sourcing, and data layers for microservices.

Transcript

1. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Domain-Driven Data — Bradley Holt Developer Advocate Senior Software Engineer
4. A fully-managed database-as-a-service (DBaaS) based on Apache CouchDB with additional full text and geospatial search capabilities IBM Cloud / February 9, 2018 / © 2018 IBM Corporation
5. Open for Data Dome (outside) by Bradley Holt.
6. Brent Spiner with Zoltar from Big by Bradley Holt, on Twitter <https://twitter.com/BradleyHolt/status/702311271002087424>. Big Data
7. IBM Cloud Data Services IBM Cloud / February 9, 2018 / © 2018 IBM Corporation
8. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation A Brief History of Data
9. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation The Relational Database order *order_id customer_id date customer line_item *customer_id email_address name *order_id *item_id price quantity database 2 by Tim Morgan, on Flickr <https://flic.kr/p/7Frdi> (CC BY 2.0).
10. Relational databases guarantee atomicity, consistency, isolation, and durability (ACID) IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Hard Disk by Jeff Kubina, on Flickr <https://flic.kr/p/uS4zk> (CC BY-SA 2.0).
11. The ACID guarantees provided by relational databases were (and often still are) critical for systems of record IBM Cloud / February 9, 2018 / © 2018 IBM Corporation IBM 360 Announcement center by Robert Nix, on Flickr <https://flic.kr/p/bu2gfG> (CC BY 2.0).
12. The introduction of the Web brought new types of applications with different constraints than systems of record IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Dialing Up Web History by Mike Licht, on Flickr <https://flic.kr/p/cacNad> (CC BY 2.0).
13. The introduction of mobile apps added to the growing number of systems of engagement IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Instagram and other Social Media Apps by Jason Howie, on Flickr <https://flic.kr/p/d41HES> (CC BY 2.0).
14. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Changing Constraints
15. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Always On Dynamo, un siècle de lumière et de mouvement dans l'art, 1913 – 2013 by Yann Caradec, on Flickr <https://flic.kr/p/ebpwib> (CC BY-SA 2.0).
16. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Big Data World travel and communications recorded on Twitter by Eric Fischer, on Flickr <https://flic.kr/p/b7ntgR> (CC BY 2.0).
17. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation The CAP Theorem Consistency Availability Partition Tolerance
18. Horizontal scaling through the addition of commodity hardware IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Server grill with blue light by David Precious, on Flickr <https://flic.kr/p/cfXKY1> (CC BY 2.0).
19. Every node in an eventually consistent distributed system will eventually arrive at a consistent state if given no new updates IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Spider Web by Alden Chadwick, on Flickr <https://flic.kr/p/z4hgz1> (CC BY 2.0).
20. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Enter “Not only SQL” (NoSQL)
21. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation key-value graph document …more database by Tim Morgan, on Flickr <https://flic.kr/p/7DUk5> (CC BY 2.0).
22. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation
23. Key-value stores provide opaque data accessed through unique keys IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Keys for the Stanley Hotel by Mike Silva, on Flickr <https://flic.kr/p/z6P3RM> (CC BY 2.0).
24. Document databases are a variation on key- value stores with strictly defined values (e.g. JSON objects) IBM Cloud / February 9, 2018 / © 2018 IBM Corporation paper by malik, on Flickr <https://flic.kr/p/aZjTXv> (CC BY-ND 2.0).
25. Graph databases provide nodes and properties of nodes connected via edges IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Edinburgh Road Network analysis by Steven Kay, on Flickr <https://flic.kr/p/ao19br> (CC BY-ND 2.0).
26. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Domain-Driven Design (DDD)
28. Domain-Driven Design is a collaboration between domain experts and software practitioners IBM Cloud / February 9, 2018 / © 2018 IBM Corporation IMG_2619 by Jason Pelletier, on Flickr <https://flic.kr/p/k7Mp2C> (CC BY-SA 2.0).
29. Complexity is in the domain, not in the technology IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Sounds_of_Complexity11.jpg by Enzo Varriale, on Flickr <https://flic.kr/p/4pC77a> (CC BY-ND 2.0).
30. Models are tools used to solve problems within the domain IBM Cloud / February 9, 2018 / © 2018 IBM Corporation model by MaZzuk, on Flickr <https://flic.kr/p/3fUREM> (CC BY 2.0).
31. Don't confuse models with reality—the map is not the territory IBM Cloud / February 9, 2018 / © 2018 IBM Corporation taking the subway to find the rents by Eli Duke, on Flickr <https://flic.kr/p/2z4udd> (CC BY-SA 2.0).
32. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Building Blocks of DDD and Domain Object Life Cycle
33. Entities are defined by their identity IBM Cloud / February 9, 2018 / © 2018 IBM Corporation DSC_3407 by Mad House Photography, on Flickr <https://flic.kr/p/7EUfbx> (CC BY 2.0).
34. Value objects encode attributes that describe things IBM Cloud / February 9, 2018 / © 2018 IBM Corporation red numbers by DaveBleasdale, on Flickr <https://flic.kr/p/6hkJWo> (CC BY 2.0).
35. Aggregates group related entities to minimize complexity IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Social graph by Dmitry Grigoriev, on Flickr <https://flic.kr/p/fnzLPk> (CC BY 2.0).
36. Repositories provides the illusion of in- memory data stores IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Catalog. by Adam Mayer, on Flickr <https://flic.kr/p/282Bh> (CC BY-SA 2.0).
37. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Domain Layer Order Aggregate «interface» OrderRepository + insertOrder(order:Order) + updateOrder(order:Order) + findOrderById(id:int) : Order + recentOrders([limit:int]) : Order[0..*] Customer … Infrastructure Layer LineItem … Order - id : int - customer : Customer - date : Date - lineItems : LineItem[1..*] + total() : Money InMemoryOrderRepository + insertOrder(order:Order) + updateOrder(order:Order) + findOrderById(id:int) : Order + recentOrders(limit:int) : Order[0..*] RelationalMapperOrderRepository + insertOrder(order:Order) + updateOrder(order:Order) + findOrderById(id:int) : Order + recentOrders(limit:int) : Order[0..*]
38. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Choosing the Right Data Layer
39. A repository cannot completely abstract the constraints of your data store IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Lina Bo Bardi, SESC Pompéia by paulisson miura, on Flickr <https://flic.kr/p/a8dwVr> (CC BY 2.0).
40. Object-oriented programming and relational databases use different models, resuting in the object-relational impedance mismatch IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Financial District Classical Building Reflection Distortion, San Francisco, California, USA by Wonderlane, on Flickr <https://flic.kr/p/5rnE8S> (CC BY 2.0).
41. “This is the world of NoSQL to me, that we can choose a tool that fits well with the problem we’re trying to solve.” Eric Evans (author of Domain-Driven Design) Software Engineering Radio Episode 226: Eric Evans on Domain-Driven Design at 10 Years, 2015 IBM Cloud / February 9, 2018 / © 2018 IBM Corporation http://www.se-radio.net/2015/05/se-radio-episode-226-eric-evans-on-domain-driven-design-at-10-years/
42. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Strategic Design
43. Bounded contexts allow different models to be used within different domain contexts IBM Cloud / February 9, 2018 / © 2018 IBM Corporation rectangles by Dean Hochman, on Flickr <https://flic.kr/p/iPpAs8> (CC BY 2.0).
44. Each bounded context should have its own data layer, and should not directly access a data layer belonging to a different bounded context IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Hexagons by Henry Burrows, on Flickr <https://flic.kr/p/e9sTjU> (CC BY-SA 2.0).
45. A data layer may be a database, or it can be a data system consisting of multiple databases— sometimes called polyglot persistence IBM Cloud / February 9, 2018 / © 2018 IBM Corporation FLOWERS Mixed Boquet by kazandrew, on Flickr <https://flic.kr/p/4a3Yyk> (CC BY-SA 2.0).
46. Each bounded context may be represented as a microservice or a cluster of microservices IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Rainforest Biome by BMiz, on Flickr <https://flic.kr/p/fpLRzV>.
47. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Catalog Document Database Key/Value Store Graph Database Full Text Search Shopping Cart Document Database Key/Value Store Orders Relational Database Big Data Analytics
48. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Alternative Architectures
49. Rather than update an entity in place, Command Query Responsibility Segregation (CQRS) provides separate read and write models IBM Cloud / February 9, 2018 / © 2018 IBM Corporation rectangles-10 by Karen Cropper, on Flickr <https://flic.kr/p/wHWeTA> (CC BY 2.0).
50. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Domain Layer Read Model «interface» OrderQueryHandler + findOrderById(id:int) : OrderDetails + recentOrders([limit:int]) : OrderSummary[0..*] Write Model OrderDetails + getId() : int + getCustomer() : Customer + getDate() : Date + getLineItems() : LineItem[1..*] + getTotal() : Money «interface» OrderCommandHandler + handle(command:CreateOrder) + handle(command:AddLineItem) CreateOrder - customer : Customer - date : Date - lineItems : LineItem[1..*] OrderSummary + getId() : int + getDate() : Date + getTotal() : Money AddLineItem - orderId : int - lineItem : LineItem
51. Event sourcing is an architecture in which application state is computed from a sequence of events IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Rusty Chain by veggiefrog, on Flickr <https://flic.kr/p/4tfcMy> (CC BY 2.0).
52. IBM Cloud Data Services IBM Cloud / February 9, 2018 / © 2018 IBM Corporation
53. Thank you IBM Cloud / February 9, 2018 / © 2018 IBM Corporation Bradley Holt Developer Advocate Senior Software Engineer — ibm.com
54. IBM Cloud / February 9, 2018 / © 2018 IBM Corporation