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1answer
37 views

Event Sourcing , sagas, bus and eventual consistency

I am currently learning about Event Sourcing via the book Microsoft .NET - Architecting Applications for the Enterprise. Event sourcing is, in my own words, an architectural pattern of storing ...
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0answers
40 views

DDD and read models - where to use? [closed]

I'm coding an application using DDD and EventSourcing (therefore CQRS) for the first time. My aggregates are stored in an event stream, so they are not good for querying. That's why I'm building a ...
1
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2answers
118 views

What are the differences between Event Sourcing and Service Layer pattern?

I am reading a book on architecting enterprise applications. In this book the Event Sourcing pattern is introduced which can be used as the "command" part of a Command and Query Responsibility ...
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0answers
27 views

Propagating events between applications [closed]

For a long time our time is discussing about propagating global events between applications that could (but don't have to) be on different servers. We have few solutions but we can't find perfect one. ...
4
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2answers
105 views

CQRS: How to restore read model

It's very interesting how to restore read model in system based on CQRS. In regular mode system processes commands, creates domain events and posts them to message bus. Then another part of system ...
0
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1answer
40 views

Event sourcing – finding aggegate by different property than ID

Is there any mechanism or best practise for finding aggregates by different property than aggregate ID? I'll try to explain my question on example. There is Cart aggregate (event-sourced) and ...
1
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1answer
106 views

Domain driven design with eventual consistency

My domain aggregate is struggling with simple business logic so I feel like I have modeled it incorrectly. The architecture I have right now uses domain driven design with event sourcing. The domain ...
0
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1answer
38 views

How to model complex event in event sourcing?

Lets say that we have a user (like super-hero) that want to see all wars that is going on in a world so that he can stop them. He can't prevent them all, because he needs to sleep sometimes and so on. ...
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0answers
65 views

Is Event sourcing a good fit for database sync (master-multiple-slaves)?

I'm looking for a good way to maintain in sync local sqlite databases that could be offline to a master one, for a invoice app. Then I read about EventSourcing and Log structured storage and wonder ...
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0answers
122 views

How to handle duplicate events when replaying event store?

If two aggregates are listening to the same event; then the event will be stored in an event store twice, once for each aggregate. class ItemLoaded implements Event { LocationId location; ...
6
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1answer
374 views

Event sourcing and REST

I came across Event Sourcing design and I would like to use in an application where a REST client is needed (RESTful to be precise). However I fail to connect these together as REST is quite CRUD-like ...
2
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2answers
126 views

Which events to store with event-sourcing?

I'm planning out the events that my application will be creating, but am running into problems with my design. I believe I'm not applying the event-sourcing concepts correctly. Take the bank account ...
2
votes
1answer
415 views

Event sourcing - performance penalty? [closed]

I am trying to convince people in my company that we should switch to event sourcing. Our software is a product that consist of many modules - like a module for wiki, blogs, documents, etc. I would ...
4
votes
2answers
251 views

At what granularity are events recorded in Event Sourcing?

I'm growing my understanding of event sourcing. My understanding is that it provides a means of recording events as they happen so that given a common beginning state and an audit log of recorded ...
1
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1answer
120 views

What should the payload of a “domain event” generated through “change data capture” include?

Using domain driven design and event sourcing ... Given I have a table of 3 columns: (A, B, C) with an existing row of data: (1, 2, 3), when I update the row to contain values (1000, 2, 3) and I run ...
3
votes
1answer
791 views

Fire domain events after transaction completes

I am trying to implement a domain event system that only fires its events when the associated unit-of-work commits successfully. The main reason why I want to do this is because I have other ...
1
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1answer
197 views

Version hash to solve Event Sourcing problems

The basic examples I have seen about Event Sourcing do not deal with out of order events, clock offsets in different systems and late events from system partitions. I am wondering if more polished ...
1
vote
1answer
128 views

In event sourcing, is it ok to introduce a dependency in my message class?

Following Martin Fowler's explanation on event sourcing, I have a message class that looks something like this: ShippingEvent { Process(Ship ship) {} } However, in my case, I need to talk to ...
1
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0answers
110 views

Event Sourcing for Enterprise Applications [duplicate]

Is it viable to store information a la event sourcing when dealing with large enterprise applications ? I know lokad has been using it for a long time, but they are not in the ERP business I have ...
3
votes
1answer
876 views

How Add/Create* commands should be handled in CQRS + Event Sourcing architecture

I want to implement my first application using CQRS pattern along with Event Sourcing. I am wondering how creation of aggregate roots should be handled properly. Let's say someone sends CreateItem ...
1
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1answer
323 views

Should I really need to implement event sourcing is this case?

An example of use case when event sourcing is applicable here whose excerpt is: Say, something went wrong in your app and as a result, a user gets blocked for abuse but that user claims to not ...
4
votes
3answers
279 views

Where should an object in CQRS+ES be fully initialized: in the constructor, or when applying the first event?

There appears to be widespread agreement in the OOP community that the class constructor should not leave an object partly or even fully uninitialized. What do I mean by "initialization"? Roughly ...
1
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2answers
1k views

Audit trails and recording actions

Background A discussion that has come up at work recently is how we handle audit logging and the recording of events. We are integrating with a 3rd party app so triggers are a no no from the off so ...
6
votes
5answers
328 views

design for interruptable operations

I couldn't find a better topic but here it is; 1) When user clicks a button, code starts t work, 2) When another button is clicked, it would stop doing whatever it does and start to run the second ...
7
votes
3answers
2k views

Event sourcing and persistence

I'm reading up on event sourcing and have a question regarding persistence. I can still have a DB with all entities, right? Or should the events be replayed every time the application is started to ...
3
votes
2answers
653 views

Inheritance, commands and event sourcing

In order not to redo things several times I wanted to factorize common stuff. For Instance, let's say we have a cow and a horse. The cow produces milk, the horse runs fast, but both eat grass. ...
4
votes
2answers
990 views

Distributed application using RabbitMQ

I am on my way to create an application with 4 bounded context using CQRS & event sourcing. In order to make these bounded context talk to each other I was planning on using Rabbit MQ. My ...
3
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1answer
1k views

CQRS + Event Sourcing: (is it correct that) Commands are generally communicated point-to-point, while Domain Events are communicated through pub/sub?

Didn't know how to shorten that title. I'm basically trying to wrap my head around the concept of CQRS ( http://en.wikipedia.org/wiki/Command-query_separation) and related concepts. Although CQRS ...
9
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2answers
4k views

DDD, Saga & Event-sourcing: Can a Compensate Action simply be a delete on the event store?

I realize the above question probably raises a few 'what??'s, but let me try to explain : I'm trying to wrap my head on a couple of related concepts, basically the Saga-pattern ( ...
6
votes
1answer
713 views

Is event sourcing ready for prime time? [closed]

Event Sourcing was popularized by LMAX as a means to provide speed, performance scalability, transparent persistence and transparent live mirroring. Before being rebranded as Event Sourcing, this type ...
11
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3answers
2k views

Are Domain Objects in Domain Driven Design only supposed to be write-only?

I've been reading about Domain Driven Design for almost two years and have been cautiously been introducing some concepts in to my daily work or at least making plans for how things I do regularly ...
2
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2answers
242 views

Backward compatibility with event-sourcing

How do you stay backward compatible with event-sourcing? Let say you release a version that has one kind of event, let call it X. You know how to handle that event in all the systems that extracts the ...
2
votes
2answers
422 views

How do you end up with event-sourcing if you use a xDD approach?

When working in a TDD or BDD manner your unit tests are supposed to drive your design. But how do you end up with event-sourcing using a xDD techniques? As I see it event sourcing is something you ...