Vaughn Vernon (@VaughnVernon@mastodon.social) @VaughnVernon Twitter profile

Pinned Tweet

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

I finally realized what's been on my mind for the past 15 months.

24

49

537

Last Seen Profiles

@BibbleJhonson

@RANJEET74965231

@RopsonPL

@MilindPariwakam

@babyysuji

@rollins

@TI_metal

@yourfavgymbro

@RarrochaR

@thesouzx

@pinkywtw

@RiyanRi36728744

@HHS_Global

@maryspace__

@carnetBCN

@dai_jove

@YwP00Me4RW7MA5a

@kkpapua1

@sandeepinc_

@LuvenAdelmu

@SeraElen

@OnlineS00831450

@Moohorse

@babyysuji

@Whosentu191208

@Pulse_Rts

@aubsksi

@luckylou_666

@_zTeemper

@BxlentSports

@ph_sizsiz

@parnu_stcroix

@fchs_softball

@KeepUpWithNef

@AFC_Adi06

@keyla_mcclure

Vaughn Vernon (@[email protected])

@VaughnVernon

10 months

Dependency injection has had strange effects on software developers. For example, not using an IoC container or DI at all, I use object constructors that require correct parameters: var proposal = new Proposal(client, expectations); The DI addicted onlookers informed me that

88

141

876

Vaughn Vernon (@[email protected])

@VaughnVernon

5 months

Event Sourcing and Message Streaming are NOT the same things. Kafka is NOT suitable for Event Sourcing. Kafka is suitable for Message Streaming. There are important reasons why these two different things require *different storage mechanics*. I'm going to simplify this by naming

18

121

580

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

"Microservices are very successful in solving the disadvantages of monolithic architecture" No. No, they are not.

37

88

531

Vaughn Vernon (@[email protected])

@VaughnVernon

11 months

Avoid collection-named behaviors where possible: // Meaning is vague void AddStudent(Student student) { ... } // Meaning is explicit void Enroll(Student student) { ... } #dddesign

22

71

480

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

My Vaughn Vernon Signature Series cover design is finalized. The series theme is based on organic systems and techniques. All cover images fit that. Here's the cover (comp, not final) of the book by @tjaskula and me. A cactus is prickly and beautiful, parts large and small. 1/4

18

90

403

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

"Really Simple CQRS"

Really Simple CQRS

Whenever I teach my IDDD Workshop and reach the first section that discusses CQRS (Command-Query Responsibility Segregation) I ask if anyone is already

kalele.io

7

141

380

Vaughn Vernon (@[email protected])

@VaughnVernon

10 months

A common misunderstanding about technical debt is that it's incurred by releasing "bad code." That's incorrect. It's a metaphor for releasing a model that you know is wrong based on new knowledge. The team releases with debt in order to receive feedback earlier than if time were

11

73

298

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

The programming part is pretty easy compared to the thinking part.

12

108

292

Vaughn Vernon (@[email protected])

@VaughnVernon

4 months

The world would be a much better place if every programmer used the Tell-Don't-Ask principle. That means to do this: quote.extendExpirationBy(days); Not this: LocalDateTime dt = quote.getExpirationDateTime(); dt = dt.plusDays(daysToAdd); quote.setExpirationDateTime(dt);

15

57

259

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

I find it amusing that those who claim to be using DDD and teaching others how to use DDD aren't willing to look up the meaning of a word in a dictionary. Takes less time to find than tweet. DDD is not about aggregates and invisible messaging. It's about language in a context.

3

80

251

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

"Events are actions..." Events are *not* actions and don't necessarily represent future actions. A command represents the potential for future action. An event is a factual record that an action took place. Consumers should translate events to commands to react to the events.

15

40

250

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

If you want to understand what #CQRS is and isn't, I suggest reading my years-old blog post that explains CQRS from several angles and helps simplify its use: "Really Simple CQRS" It also corrects much of the current confusing messaging about it.

Really Simple CQRS

Whenever I teach my IDDD Workshop and reach the first section that discusses CQRS (Command-Query Responsibility Segregation) I ask if anyone is already

kalele.io

4

54

224

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Hola amigos, with Google celebrating mariachi today and all, we thought it's a good time to release #DDDesign Distilled in Spanish. Get your copy of "Domain-Driven Design Destilado" here. It's free/gratis to all.

Domain-Driven Design Destilado

Domain-Driven Design Destilado by Vaughn Vernon Register for Your Free Copy

kalele.io

21

91

222

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Hey, my Spanish speaking friends! Available soon: the Spanish translation of my #DDDesign Distilled book provided for FREE/GRATIS on . Everyone who speaks and reads Spanish as the language of their heart should learn #DDD . Please RT for broad reach.

11

141

219

Vaughn Vernon (@[email protected])

@VaughnVernon

6 months

Own 19 great software engineering and software development books for $25.00 (a $671.00 value for $1.31 each), including: - My #DDDesign Distilled - My Strategic #Monoliths and #Microservices - All books in my @pearson Addison Wesley Vaughn Vernon Signature Series Why would

13

56

210

Vaughn Vernon (@[email protected])

@VaughnVernon

2 months

@ardalis The 5 Laws of Estimates: 1. D 2. O 3. N 4. ' 5. T

6

19

189

Vaughn Vernon (@[email protected])

@VaughnVernon

5 months

These two figures from Chapter 8 of "Strategic Monoliths and Microservices" show how simple Hexagonal architecture is. Figure 1 is the whole architecture in one process. Figure 2 shows Inside versatility; lower right shows the Outside Imperative Shell around a Functional Core.

6

45

178

Vaughn Vernon (@[email protected])

@VaughnVernon

4 months

Here's an #EventStorming Cheat Sheet created in @kalele_domo Try Domo. It's free.

4

27

178

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

#MonolithicArchitecture != Tight Coupling #BigBallOfMud == Tight Coupling #ROI is in differentiated strategic innovation, not in a deployable container. Architect for purpose.

1

19

176

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

#DDDesign is not an architecture.

4

19

164

Vaughn Vernon (@[email protected])

@VaughnVernon

2 months

🥺🙄🤨 "Domain-Driven Design: ... of CQRS and Event Sourcing" 🤨🙄🥺 I hope that one day, it will be broadly understood that it's not CQRS/ES (ES for Event Sourcing) and that both CQRS and ES are orthogonal to #DDDesign . DDD is not synonymous with CQRS/ES and DDD required

14

37

165

Vaughn Vernon (@[email protected])

@VaughnVernon

5 months

"Hexagonal Architecture: Common Pitfalls" There are no pitfalls with Hexagonal (Ports & Adapters), only with the people implementing it. Adapter -> Driver-Port -> (Do-Stuff) -> Driven-Port -> Adapter The domain model, anemic/rich, is not part of Hexagonal but can exist inside.

9

30

164

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

When you start with this, monolith to microservices is a few days away. You may even decide not to.

6

65

160

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Y'all, this new book in my signature series will blow your mind. I love software patterns, and this is one of the best I have seen. If you are working with REST, messaging, and/or RPC, you are going to be thrilled. It will be available by December.

Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges (Addison-...

Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges (Addison-Wesley Signature Series (Vernon))

www.amazon.com

5

36

160

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Prove them wrong. - Anemic has more lines of code - Anemic can't emit events - Anemic cannot be (thoroughly) tested - Anemic has invisible clients everywhere - Anemic has no behavior to reason about - Anemic has all the impl overhead with zero benefit

Sebastian

@SebastianBortz

4 years

@VaughnVernon How do i convince a colleague for switching from an anemic model to a domain model? Does anyone have ideas or tools with super power that help with someone having strong opinions about it?

14

1

10

8

60

164

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Complexity bias and why complexity sells better than simplicity. "Cognitive biases occur in order to save mental energy."

Complexity Bias: Why We Prefer Complicated to Simple

Complexity bias is a logical fallacy that leads us to give undue credence to complex concepts. Faced with two competing hypotheses, we are likely to choose the most complex one.

fs.blog

3

60

160

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

People are suddenly complaining about #DDDesign Aggregates. In reality, Aggregate is not a complex pattern. I've been explaining simple designs for 12 yrs. Still, I don't understand why people insist on Aggregates when use cases prove they aren't needed. Basic Entity is fine.

6

11

160

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

Free comedy. A guy that has never used #DDDesign writes about how bad it is by comparing it to a Waterfall project back in the 1990s and then exemplifies someone not using DDD failing at it along with whack "domain experts." You can't make this stuff up.

29

22

159

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

One of the most straightforward and effective design tools is modules. One of the least well-used design tools is modules. How? See: - "Implementing Domain-Driven Design" - "Strategic Monoliths and Microservices" - Correctly applying Java package, C# namespace, Ruby module...

4

24

159

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

This Impact Map template shows (1) the difference between problem/strategic and solution/tactical design, and (2) most Scrum/Agile teams start at the right (tactical) rather than left (strategic) because stories are written before knowing the *why*. #ImpactMapping #DDDesign

3

48

155

Vaughn Vernon (@[email protected])

@VaughnVernon

25 days

Satya Nadella announced that Linux wins the desktop.

Tsarathustra

@tsarnick

25 days

Satya Nadella says Windows PCs will have a photographic memory feature called Recall that will remember and understand everything you do on your computer by taking constant screenshots

5K

4K

11K

14

13

159

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

When you have figured out that common REST usage is very tightly coupled (not that it is by necessity), you really should embrace the next level. I have been promoting message- and event-driven for several years. "Post-REST: Messaging and Eventing"

6

64

143

Vaughn Vernon (@[email protected])

@VaughnVernon

5 months

One of the worst mistakes that people make is trying to get approval for using #dddesign . If you are doing it right, you shouldn't have to ask permission or get backing for #dddesign . Really. Most enterprise software could make major strides forward just by replacing the

13

27

145

Vaughn Vernon (@[email protected])

@VaughnVernon

11 months

No, Strategic Design is not the use of the Strategy design pattern. And, no, DDD is not an architecture style even if someone with a bazillion followers says it is. #dddesign

5

18

143

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

New book in my signature series now available: "Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges" By Olaf Zimmermann, @m_st , @duebke , @uwe_zdun , @pautasso

3

22

137

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Losing one parent is devastating. Losing both parents within 10 months of each other is crushing me. By last evening the last of the two cowboys from @DDD_Corral is gone. As all of my books indicate, my parents were two of my larger-than-life pillars. Writing it honored them.❤

31

1

140

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

A database schema is not a contract. An API is. If management wants to use database integration ("it's what we do"), ask them why they need contracts for the people they hire. Explain that all you need is VPN access and all they need is a mailing address to pay for your work.

11

39

139

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

I was informed that my print copy of "Principles of Web API Design" by @launchany has been shipped. Let me know when you receive(d) yours. The race is on.

6

19

134

Vaughn Vernon (@[email protected])

@VaughnVernon

7 years

Just posted "Reactive Microservices" using #DDDesign for #Reactive #Microservices

6

65

132

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

If you are writing an Entity/Aggregate to a store and then publishing an event afterward, you are doing it wrong. There's no guarantee that the event will be published, with results just as bad as a failed REST call chain. Persist Entity+Event atomically and then publish.

3

19

130

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Read "Microservices and [Micro]services" Taking a lesson from microprocessors can help us better understand the *purpose* of microservices.

Microservices and [Micro]services

The week began as busy as ever. And then I learned that one more task — beyond everything else on my plate — must be accomplished.

kalele.io

5

57

130

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Software development is: 11% mapping stuff 4% figuring out stuff to map 23% being wrong about what to map 62% getting sidetracked on slack

4

27

130

Vaughn Vernon (@[email protected])

@VaughnVernon

21 days

Why do people refer to Node.js as a programming language? I mean, I know it's because nobody understands anything anymore. So my real question is, why doesn't anybody understand anything anymore?

19

10

125

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

The point of single-team Bounded Contexts is that you want a consistent Ubiquitous Language. When multiple teams work on a single Bounded Context they will fracture and jumble the language with resulting incertitude. That's contrary to the goals of DDD.

4

58

124

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

"Decoupling" is way overused. Coupling is unavailable. If A uses B, A is coupled to B. If B changes its interface used by A, A will have to change: A->B You might alleviate the direct dependency: A->B1->B Yet, A is still coupled to B, and now B1 too. A->B is just less obvious.

32

11

124

Vaughn Vernon (@[email protected])

@VaughnVernon

8 years

My new book "Domain-Driven Design Distilled" is available on Amazon for pre-order:

Domain-Driven Design Distilled

www.amazon.com

8

70

119

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Mine arrived today: "Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges" Learn about the MDSL that is so much simpler than the #OpenAPI spec and can be used to generate it.

2

16

117

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Bounded Context: The idea is to accept and embrace differences across a single business enterprise as normal rather than anomalous.

3

35

118

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

Developers are addicted to complexity, as if intentionally complex code is a goal. Team and individual performance reviews should be based on producing simplistic, readable code. Q: How is unnecessary complexity determined with simplicity thinkers being so rare? A: Tools.

8

36

117

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

I've been saying "Management has weaponized Scrum as a means to drive developers for more, more, more, faster." Agile is a mindset. Learn it, iterate, deliver, and don't forget about Knowledge Acquisition. /via @RonJeffries

Ron Jeffries Says Developers Should Abandon "Agile"

Ron Jeffries, author, speaker, one of the creators of Extreme Programming (XP) and a signatory of the Agile Manifesto back in 2001, shared a post on his blog in which he advocates that developers...

www.infoq.com

4

68

118

Vaughn Vernon (@[email protected])

@VaughnVernon

3 months

I hate Scrum. I don't care whether anybody cares, even though they should care *why* I hate Scrum. Quote me. Will I use Scrum if a client uses Scrum? Of course, even though they probably suffer from using it.

Riccardo Causo

@rixlabs

3 months

Do you hate SCRUM? Guess what? Nobody cares. For every person hating something, there are a million loving it. Scrum is just an example. There is so much polarizing content on this platform that it is difficult to have real conversations. I fell for this engagement game too

18

2

18

8

113

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

Developers say that they will "attempt to apply Conway's Law more in the future." When you develop software you are always subject to Conway's Law. You develop software designs which are copies of your organization's communication structures. Good or bad, it's unavoidable.

8

43

115

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

The first book in my Signature Series is published: "Continuous Architecture in Practice: Software Architecture in the Age of Agility and DevOps" It's available now on @InformIT and soon on other US retailers ( @amazon ); a bit longer elsewhere.

6

23

115

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

💥💥💥ebook Now Available💥💥💥

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

"Strategic Monoliths and Microservices" by @tjaskula and me is available for purchase on @InformIT . Hopefully pre-orderers have been notified. The print book is further delayed due to ongoing supply chain issues. The new availability date is 19 November.

5

11

34

2

28

115

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

My new book co-authored with @tjaskula will be published soon and is now available for pre-order for a 45% discount through US Labor Day using this coupon: BACKTOLEARN

4

28

112

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

If you've been developing software for 15 years or so, you've probably realized: New is the new old.

3

23

114

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

The "problem" w TDD is that the second D is for Development, not Design, and software Developers think of Test purpose in terms of unit correctness. Tests to facilitate design are "Acceptance Tests" Tests to assert unit correctness are "Unit Tests" Simple. #DDDesign Distilled

6

15

113

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

A cheat sheet for #EventStorming provided by @0xcafebabe shows a blend of big-picture and design-level techniques.

GitHub - wwerner/event-storming-cheatsheet: Short cheat sheet for preparing and facilitating event...

Short cheat sheet for preparing and facilitating event storming workshops - wwerner/event-storming-cheatsheet

github.com

1

49

114

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

#EventSourcing is now well past the peak of inflated expectations and trough of disillusionment. That means we're entering the slope of enlightenment. Watch this space.

5

19

111

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

The other night a developer argued that anemic models are simpler than rich, fluent, behavioral domain models. Anemic is easier, not simpler, and lazy-easy as a resolve leads to the wonders of mud. Of course getters/setters are easy to produce, but impossible to test how used.

4

46

111

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

Raspberry Pi 4, with 1 GB RAM is $35. Raspberry Pi 4, with 4 GB RAM is $55. I estimate that many business enterprises could be run on this hardware. Suggestion: Start a cloud platform that runs RPi 4 with Debian and sell for 1/3 the cost of AWS/Azure; revenue by the ton.

10

20

101

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

From "Strategic Monoliths and Microservices" ***Migration to Microservices is NOT a Project*** The characteristics of a project include plans, scheduled workload, allocation of resources and developers, a starting date, various milestones, and probably an end date. 1>

5

25

100

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Gregor's Law ( @ghohpe ): "Excessive complexity is nature’s punishment for organizations that are unable to make decisions." You might not understand until you read subhead "Gregor's Law - Making Decisions" I think it is closely related to @conways_law

Here’s why enterprise IT is so complex

Enterprise IT is routinely plagued by excessive complexity. It might be subject to the Second Law of Thermodynamics but it’s certainly subject to Gregor’s Law.

architectelevator.com

1

31

102

Vaughn Vernon (@[email protected])

@VaughnVernon

7 years

I say this often, and it's rejected almost as often.

3

73

100

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

How to fail at Bounded Context collaboration without even trying.

7

54

98

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Congratulations to the authors in my signature series who reached the published-book milestone in 2021. Thank you all for helping make the series a unique knowledge source for modern software development. @muraterder @PGP60 @eoinwoodz @hofstef @hschwentner @launchany @tjaskula

2

18

100

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

#EventStorming

1

34

99

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

In Implementing #DDDesign why use Anticorruption Layer rather than a Repository to integrate with another Bounded Context? Typically the Repository pattern is used as an Adapter in front of a database. In general you could think of a Repository as an AcL over a database. 1/6

4

24

98

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

#DDDesign Bounded Contexts make excellent subsystem boundaries. Separation by language is logical. There's no need for such a boundary to be deployed as one microservice. Yet, if you have a good reason to use microservices, a full Bounded Context is a sensible starting point.

4

25

93

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

Learn why software architecture often hijacks domain modeling, and how to shift to innovative thinking.

Architecture vs Model

One of the biggest problems with business software is that architecture gets promoted more than the domain model. Further, most domain models are

kalele.io

1

30

98

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

Diagramming Processes. Take your pick. 1. Sequence Numbers; difficult to show contexts

2

27

97

Vaughn Vernon (@[email protected])

@VaughnVernon

2 months

@propensive I'm sorry to hear about all this. I had no idea what had happened, only that you disappeared. I thought it must have happened due to the Scala hullabaloo some years ago. I'm glad the root cause has been overcome and that your healing process has begun. I wish you all success

1

5

95

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

Timeline pressures don't cause you cut corners, take quality-compromising shortcuts, and write bad code. Timeline pressures give you an excuse to cut corners, take quality-compromising shortcuts, and write bad code. Don't.

8

39

95

Vaughn Vernon (@[email protected])

@VaughnVernon

4 months

PSA: Trunk-based Development (TBD) is not the new name for Continuous Delivery (CD). Also PSA: Ports & and Adapters (formerly named Hexagonal) Architecture does not mean: DDD, Event Sourcing, CQRS, Kafka, Kubernetes (and whatever else some people can think of). Yet another PSA:

3

19

93

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

A hybrid FP and OO architecture makes sense to me. FP is really great for certain things, but when you must produce effects due to the outside world of mutable state devices, why not hand that over to infrastructure code in OO? It's a mature, unbiased approach. /cc @tjaskula

8

33

94

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Event-Driven Architecture is as much about ownership of data and responsibility as it is distribution. In other words, the distribution is for ownership responsibility, not for copying or reimplementation. Distribution can be within monolithic modules or microservices.

3

19

93

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

Microservices to Monolith. That's what happens when you choose an architecture before understanding whether its benefits will apply. Yet, you must be mature and secure persons and team to change it to the "uncool," yet best architecture for the *purpose*.

2

27

91

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

The new book "Continuous Architecture in Practice: Software Architecture in the Age of Agility and DevOps" by @muraterder @PGP60 & @eoinwoodz is now featured on @InformIT . This first book in my signature series has a print & ebook bundle for only $48.59.

2

13

89

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

Why #reactive ? Software has been implemented against the wrong hardware architecture for the past 16 years. We don't purchase faster CPUs every 18-24 months. We purchase more cores. Software runs inefficiently because it's not designed for multicore & obsolete before it deploys.

1

34

88

Vaughn Vernon (@[email protected])

@VaughnVernon

8 months

There's a mistaken impression that asynchronous communication provides loose coupling between modules. Nope. Async messaging can be direct, meaning the sender is coupled to the receiver's address and receiver to sender by message type. There is a temporal decoupling with async,

3

15

88

Vaughn Vernon (@[email protected])

@VaughnVernon

4 years

Perfection is the enemy of Useful. The "perfection" of people who don't understand agile and continuous improvement cause gigantic overruns. Archaic and backward ways of working is intolerable, and it's never perfect anyway. Ship->Feedback->Improve Simple.

3

38

88

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Every operation that involves persistence boils down to CRUD. Yet, REST over HTTP need not be used from a purely CRUD perspective. Consider the HTTP verb methods to be categories of operations. I've explained this many times, but there are so many who still need to be taught. 1/2

4

19

87

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

I just wrote to someone about an article they wrote RE CQRS. I hope it helps him & I hope posting bits of my thoughts here helps others. First: CQRS is *not* an architecture. CQRS is an architecture pattern. "An Architecture"/"Architecture Style" is about a bigger picture. 1/5

2

19

88

Vaughn Vernon (@[email protected])

@VaughnVernon

6 years

I answered an email asking why I covered ORM in my Aggregates chapter (and paper). It's because most developers that I encounter were and are still on it. Of all my blog posts the most popular is about how to avoid using ORM when stuck in relational. 🤔

5

27

85

Vaughn Vernon (@[email protected])

@VaughnVernon

7 years

Interested in Promise Theory but haven't understood? @markburgess_osl explains in less than 20 minutes in Parts1&2:

0

19

85

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

Generally people think of proactive as always better than reactive. I disagree. Decades ago I became known for saying "let's see what happens." It was usually related to software, but often life in general. Think about it: Waterfall is proactive. Being agile is reactive.

6

21

86

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

Take a first step with #DDDesign by replacing individual primitive/scalar/string attributes/properties with Value Objects that cluster those related to one another. Test new values and use. Assertion: long amount; String currency; Don't mean the same as: Money amount;

8

21

86

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

In case you missed the announcement, the new book in my signature series "Patterns for API Design" is now available in print, one month ahead of schedule. Surprise! (Amazon availability is roughly 10 days out, and the @InformIT pricing is comparable.)

1

11

84

Vaughn Vernon (@[email protected])

@VaughnVernon

7 years

Ok, I just published a blog post on this subject "Microservices with DDD: To Event Source or Not":

1

38

83

Vaughn Vernon (@[email protected])

@VaughnVernon

10 months

But, hey, Java programmers have 10,001 annotations to make bad design much easier and faster to accomplish. Some annotations actually do nothing except make said programmers feel better because they can annotate one more thing.

Martin Müller Software Craftsman

@swcraftsman

10 months

Worrying about the resistence against DDD I was faced within Java community, I started to read @VaughnVernon 's book, hoping to find answers on how to push my teamates into the right direction. Seems there's nothing new under the sun since 12 years...

0

2

22

7

10

83

Vaughn Vernon (@[email protected])

@VaughnVernon

3 years

An agile team could improve delivery so management is introducing SAFe to help them. Help is about to arrive.

4

15

83

Vaughn Vernon (@[email protected])

@VaughnVernon

5 years

I learned today that the book "Domain Storytelling" has been released. I haven't had time to read it but I hope to soon. When I do I'll try to provide a review.

3

17

83

Vaughn Vernon (@[email protected])

@VaughnVernon

7 years

If you need a quick online introduction to #DDDesign you can currently register for mine, free:

2

42

79

Vaughn Vernon (@[email protected])

@VaughnVernon

8 months

A Domain Event that is published outside your Bounded Context should be defined in your Published Language. The public API of your Bounded Context is your Open-Host Service. Open-Host Service and Published Language are generally used together, but they are distinct. #DDDesign

3

12

81

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

Behavior-Driven Development / Specification by Example are considered to have the following disadvantage: - Requires a high level of business engagement and collaboration. . . . *shakes head*

6

19

79

Vaughn Vernon (@[email protected])

@VaughnVernon

4 months

Complete decoupling is impossible for non-trivial software to function. A Domain Event couples at least one consumer service to the producer. Event translation decouples the service inside from its outside, but the outside is still coupled by necessity. Events offer the best

1

13

79

Vaughn Vernon (@[email protected])

@VaughnVernon

10 months

Assuming a #DDDesign Bounded Context requires model persistence, it should have it's own, non-shared database (at least one). That is, no other Bounded Contexts may have operational access to that database. Yet, "database" can be an overly generalized constraint: 1. The point is

5

15

80

Vaughn Vernon (@[email protected])

@VaughnVernon

1 year

Why implement Outbox & Inbox patterns? It requires significant effort, persistence and performance overhead; likely have lurking bugs; by the time you think they are right, you still haven't solved any *business* problems. Take it easy. Model uncertainty.

DDD Today - Modeling Uncertainty • Vaughn Vernon • GOTO 2017

This presentation was recorded at GOTO Berlin 2017. #GOTOcon #GOTOberhttp://gotober.comVaughn Vernon - DDD Expert Consultant & TrainerABSTRACTThe foundation ...

www.youtube.com

5

22

80

Vaughn Vernon (@[email protected])

@VaughnVernon

2 years

The DDD Score Card in "Implementing Domain-Driven Design" provides a means to determine whether you can justify the use of #DDDesign . Use it before trying to selling #DDD to your leadership.

4

15

79