Modernizing an existing system to take a more domain-driven approach - William Penberthy

Domain-driven design seems “straight-forward” when looking at green field development. Implementing that in an existing enterprise system, however, is daunting.

In this session we will go over some of the refactoring patterns that support this change and we will demonstrate the steps necessary to refactor a non-DDD SOA-based system using DDD approaches. We will talk about the kinds of decisions that have to be made, when they need to be made, and what those decisions look like in the grand scheme of your refactor.

Check out more of our talks at:

[luckyashnar]

Thank you, It was very engaging, clear and concise overview of how DDD could be applied. It helped me to understand the concept, and get some basic information in less than 1h.

[jan]

The two mentioned talks can be found here:
Implementing your first Event Driven Design - Sarah and Ann
Practical DDD with EF Core - Hossam Barakat

[andrewferguson]

This presenters speaking style is very good for playing on 1.5x speed. he doesn't speak quickly then pause but instead has uniform space between sounds and it trims super nicely

[evilsdexter]

Good talk, apart from that unnecessary comment about javascript, maybe it would be better to use "swing" to build UI's ...
Anyway, what puzzles me about using the message queue is how do we make sure that the appropriate contexts handle all the messages that they should, how do we document that and share this info between various teams in charge of these? Let's say we have an order and an inventory bounded context. The order b.c. publishes a message with something has been ordered, which gets picked up by the inventory system and the system decrements the quantities. Now let's assume that something happened to that order and the order system publishes an order cancelled message. Again the inventory system is designed to pick up and handle that (incrementing back the quantities), so all is good. Now, after an year, we get this need to have partial cancellations, and we implement it in the order bc, thus the order system will now publish a different message, a partial order cancel... but what if the guys in the inventory context didn't implement it yet? This is a simple example, however, if you have a system with many many bounded contexts, this kind of desync will happen. How does one deal with this?

[lior]

52:45 - "hippie language javascript" 😂🤣

[bepkororoti]

Ahem, having a separate way to read and write, aka CQRS, can easily be applied to the whole system, what he probably meant to say is that using event sourcing as a top level architecture can be problematic because it's a lot of effort that doesn't pay off with many types of systems that don't really need custom code for very strong domain invariants, event replay, perfect auditing etc, say, CRUD systems, where the DB already enforces most of the modeling goals. Nothing new here, watch Jimmy Bogard's talks, he always has some interesting new insight that hasn't been regurgitated to death

[mahbuburrahmanrahman]

Do you tell me Is it possible to control AC FAN dimmer (with zero cross detection) both By two Physical push BUtton (speed increasing and decreasing) manually and also By Blynk app slider button for controlling speed through wifi. I ask the question because facing very difficulties to write the code for integrating push button function with only wifi controlled code (By blunk app slider button) . do you know is it possible or not ?

[AB-fpxo]

Microservices have a lot more cons than pros. You will not be able to use transactions beyond a single microservice, latency of your app will be greatly increased, you will need a separate DevOps guy to monitor and administrate the entire infrastructure, development process will be much more complicated with microservices... etc etc etc. But at least after many companies failed at introducing microservices, now people started realizing how bad microservices are.

[yasser]

Will never work on AWS
It's crappy and expensive
And microservices honeymoon is a myth
Monolithic design is still valid, it's all about how you design it

[MrVipulLal]

Totally dry and theoretical chat. No examples used at all