I love this quote by Andy Hunt
“I find aiming to make things “replaceable” far better than making things reusable. Reusable means you’re fortune-telling, trying to divine an unknowable future.”
This is what I’m aiming for as well especially when you bring in the Sacrificial Architecture. Love it.
As you create your architecture, design all components to be replaceable, not reusable. This is a whole lot easier nowadays with AWS and Lambda creating serverless masterpieces, for example.
In this video I will show you the different types of projections in an event-based microservice architecture and how you can use them.
Projections can be created in code in your microservice or in read-models when domain events are received and processed, for example, you process a published domain event and then store the result of the analysis in Oracle, MySQL, SQL Server, etc.
I just finished uploading the final video on YouTube of the little mini-series “Microservices”. Take a look here:
1. Microservices – Part 1 of 4 – What Is A Microservice?
2. Microservices – Part 2 of 4 – DDD
3. Microservices – Part 3 of 4 – Big Ball of Mud
4. Microservices – Part 4 of 4 – Event Driven
These videos are all available on my YouTube channel at: Creating Great Software
I have just published my FREE course: “Why You Need Serverless Microservices, Yesterday“. Enroll for FREE!
In this course I will walk you through the many benefits of creating serverless microservices instead of the traditional node / instance approach including the use of containers. There are more than enough things to worry about when you want to create a new cloud system or transform a legacy system to operate in the cloud.
From a business point of view, there are huge benefits in going serverless rather than instance based (including containers). A very large jump in business agility can be achieved through focusing on the problems and opportunities rather than the technical jungle of traditional computing solutions.
From a technical point of view, it is almost nirvana where you can eliminate many points of failures in the architecture.
Update 04/03/2019: I have completed the FREE course: “Why you need serverless microservices, yesterday!“. Enroll for FREE!
At the moment, I’m working on four online courses in the following order:
“Why You Need Serverless Microservices, Yesterday“, FREE Course
In this course I will walk you through the many benefits of creating serverless microservices instead of the traditional node / instance approach including the use of containers. There are more than enough things to worry about when you want to create a new cloud system or transform a legacy system to operate in the cloud.
From a business point of view, there are huge benefits in going serverless rather than instance based (including containers). A very large jump in business agility can be achieved through focusing on the problems and opportunities rather than the technical jungle of traditional computing solutions.
From a technical point of view, it is almost nirvana where you can eliminate many points of failures in the architecture.
“How To Build An Event Store”, Paid Course
Your event store is the heart of an event sourced system. The event store is the source of truth for all business events. It needs to be able capture and replay all domain events in your system reliably and with great performance.
In this course, I will walk you through building an event store that you can re-use in your own projects. In addition, I will walk you through building a read model that allows you to query domain events from the read model.
I will also go through why building your own event store has many more advantages over using a third-party event store.
We will be building the event store in AWS DynamoDB but you can apply the design to a traditional RDMS SQL storage just as well. I will go over the pros and cons in doing so.
“Architecting And Designing Event Based Microservices”, Paid Course
Learn the details on how to design and architect event based microservices using Domain Driven Design (DDD), Event Storming, CQRS, and EventSourcing techniques. I will show you how best combine many principles, patterns, and techniques to create an architecture with as few points of failures as possible and still deliver a great solution.
What you will learn can be applied to cloud based systems but also to traditional, on-premise systems. The benefits are great in either environments.
Whether you are designing a new system in a greenfield environment or transforming a legacy system, I will show tips & tricks that you can use depending which type of project you are in.
“Implementing A Serverless Microservice in AWS”, Paid Course
Learn the details on how to implement a serverless microservice in AWS using Domain Driven Design (DDD), CQRS, and EventSourcing techniques.
We will build a fully functioning billing system in AWS using Visual Studio and C# .NET Core. Even if you are not familiar with C# and .NET Core, you will learn a lot of practical tips on using the different AWS services including building fully automated CI/CD pipelines.
I’m still working on these courses but I’m planning on publishing “Why You Need Serverless Microservices, Yesterday” and “How To Build An Event Store” first.
I just created my new YouTube channel “Creating Great Software”. Have a look.
I will be publishing videos about creating great software including serverless computing in AWS. In addition, I will be publishing my STRONG opinions about the state of the software industry from time to time.
I’m super excited about this new channel and I’m looking forward in seeing your feedback. See you there!
In the past 27 professional years, I have been fortunate enough to gain a lot of experience and wisdom in 10 different software industries. These experiences are not just successful accomplishments but also plenty of failures and mistakes made along the way. It is ok to make mistakes as long as you learn from them, only then you will gain true wisdom in anything you do.
Over the years, I have always thought, “If I could gather a small team, I could share my knowledge and we can create great things“. Due to many circumstances, I never had the opportunity to mentor a small team and being in full control on what we would create. By full control I mean free from politics and other constraints. The sort of freedom you need to create and explore ideas without worrying about budgets, timelines, etc. When you can foster such an environment, great things get invented. Just look at the past successes in Silicon Valley.
How can I share my experiences and wisdom most efficiently and help you achieve your goals much more rapidly rather than doing it alone? I have decided it is time to create an online school where I can share all my knowledge and wisdom from the software industry. Well, how about an online course that is very deep in all aspects. An online course that would teach you the birds eye view of concepts and then drills down into the very deep aspects of it. A course that could show you actually how to put the conceptual components together in a very cohesive way. All the different pieces put together in an architecture that makes real sense and is practical and maintainable. We’ll leave the fluff out and concentrate on the entire system starting from a users perspective and walk backwards into the technical implementation details. In short, a
Serverless System Master Class
This master class would be extensive and we will go into a lot of details until we have built a working system that you could use in your future projects. As a minimum, you would learn a lot of concepts and software architecture. Since technology is always changing, I believe that the concepts will be more valuable then the implementation details in the course. In addition, how you bring these concepts together and why are extremely important because in your day-to-day work, you will have constraints that you need to work with and make compromises. There is no perfect architecture and even in this master class, you will touch on many different options one could take and why.
Please let me know if you are interested in the Serveless System Master Class. I would love to hear your feedback as I work on the course. I plan to post regular updates on my blog here.
Leave a comment below or contact me directly at thomasjaeger at gmail dot com and let me know your level of interest, please!
Here are a few notes I wanted to point out when you are trying to model aggregates in domain driven design (DDD). Many times I can’t find the right words or I simply forget what the technical definitions are when you model your domain model or any parts of a domain model such as aggregates. I always go back to the fantastic book “Implementing Domain Driven Design” by Vaughn Vernon. He is a master in showing and explaining it in such a way that I can not do a better job. As I’m currently doing some modeling work over the weekend, here is a summary from how Vaughn is explaining it:
“When trying to discover the Aggregates in a Bounded Context, we must understand the model’s true invariants. Only with that knowledge can we determine which objects should be clustered into a given Aggregate.“
He talks of how you should design your aggregates. What does an aggregate consist of. So, he goes on with another perfect explanation:
“An invariant is a business rule that must always be consistent.”
Followed by another super explanation:
“Aggregate is synonymous with transactional consistency boundary.”
In the past, I made the mistake of clustering aggregates via composition: “This object A contains object B” which is wrong. Once you understand the bounded context and the aggregate’s true invariants (the business rules), you got it. You hit the jackpot. The light will come on.
Anyways, I wanted to publish this for some time now but never bothered since I always go through Vaughn’s book. But, I thought others might find this useful information especially if you are doing domain driven design and microservices.
I have updated my C# reference implementation and included FluentValidation on some of the DTO objects. I also updated the ErrorMap to include validations on the server side as well as on the WPF client side. This version also includes a sample SQL Server Persistence Provider. As always, you can get the latest code on my GitHub repo.
Wednesday, March 25th, 20015, I will be presenting “Object Persistence in C#” at the Sacramento .NET User Group (SAC.NET) at the Microsoft Office at 1415 L Street, Suite 200, Sacramento, CA 95814 starting at 6:00 pm. Maria Martinez, Co-Organizer, Sacramento .NET User Group, was kind enough in helping to get this organized. Thank you Maria. I will see you there.
Thomas Jaeger 