Category: patterns

Modeling Temporal Occurrences

The inquiry arrived: “Are time lapsed events Domain Events?” The question is the result of wrestling with whether YearEnded and similar occurrences are actually useful. The inquirer’s assertion is that rather than capturing the fact that the year ended, just send a Command that requires some outcome as a result of the fact that the year ended. Of

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Actors Are Ok!

I have been using various forms of messaging for more than 30 years. Messaging has become second nature to me, but I empathize when others say that messaging is to them unfamiliar and intimidating. Since the Actor Model is based on message passing, it stands to reason that this programming model is likewise unfamiliar and

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And Then This Happened

Tonight after midnight in Barcelona, I was in a conversation about CQRS and how using Domain Events or not using them can impact the Command Model and the projection of changes into the Query Model. This led to some interesting points raised regarding the intent of Domain Events and some basic “rules” on how they

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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 familiar with it. I have been doing this for more than six years of teaching this curriculum, and as you can probably imagine there are now far more students who raise their

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The XOOM/PLATFORM Architecture: Part 1

Several have requested a document describing the XOOM/PLATFORM architecture. So here it is. This specific article is kept relatively brief. This is in part to emphasize the simplicity of the XOOM/PLATFORM. It’s just not complicated or difficult to describe. The other motivation for brevity is not knowing entirely what architects and developers are looking for in

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XOOM: Our Open Source Reactive Platform

This new platform represents my vision for software development from years ago. I have taken a few side tracks along the way. Previously I felt that I would be better off trying to contribute my vision to heavily funded efforts that have multiple teams, those that would easily out perform me alone. That was a

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Summary of CRDTs

In this article I am going to introduce you to CRDTs, or Conflict-Free Replicated Data Types. You will see under what conditions CRDTs might be useful, why you might want to use such a data type, what kinds of CRDTs are available, and how you can use them.

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EAI Patterns with Actor Model: Message Channel

After a discussion of all those fancy doodahdah filters, routers, and buses, we are back to the plain old Message Channel. Yes, I did skip the Process Manager. We will get back to it, but for now it seems we all need a bit of boredom. Well, not really.

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EAI Patterns with Actor Model: Message Bus

You have a number of disparate business systems, from purchased commodity applications, to custom developed applications that help achieve competitive advantage, to those of integrating business partners. You need all of these systems to work together, although they run on different platforms and have various service interfaces, and each set of service interfaces specifies a

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