This is a .NET Sample Project to accompany Event Sourcing materials from the book by Vaughn Vernon: Implementing Domain-Driven Design.

Event Sourcing pattern was introduced to DDD world by Gregory Young. A+ES appendix in IDDD book and this sample are mainly based on his work in pushing the state of art in this field.

This project includes a sample domain implemented with the event sourcing pattern. Multiple persistence options are provided:

• Microsoft SQL Server
• MySQL
• File storage
• Windows Azure Blob Storage

Start by downloading sources (ZIP, Visual Studio) or by cloning a git repository:

$ git clone git://github.com/Lokad/lokad-iddd-sample.git

Then, open solution in Visual Studio (MonoDevelop might also work) and run the project. The project is auto-configured to use file storage by default, and cleans it on every start.

You should see something like:

Command: Create customer-12 named 'Lokad' with Eur
  customer-12 r0 Event: Customer Lokad created with Eur
  customer-12 r0 Event: Added 'Welcome bonus' 15 EUR | Tx 1 => 15 EUR
  Completed in 145 ms
Command: Rename customer-12 to 'Lokad SAS'
  customer-12 r1 Event: Customer renamed from 'Lokad' to 'Lokad SAS'
  Completed in 27 ms
Command: Charge 20 EUR - 'Forecasting'
  customer-12 r2 Event: Charged 'Forecasting' 20 EUR | Tx 2 => -5 EUR
  Completed in 16 ms

Then, you can dive into the code by starting with Domain folder in this solution. There also is a UnitTests project, which contains unit tests for the domain (in form of Given-When-Then specifications)

You can also try plugging in other types of event stores. Each event store requires connection string and will auto-create all required resources automatically.

If you want more details, here's what you can do next:

• Check out the Domain Driven Design community
• Dive into Lokad.CQRS Sample Project (much more detailed and practical version of this sample)
• Check out CQRS/DDD Pocket Guide and case studies
• Follow @VaughnVernon.
• Follow @abdullin.

If you have any questions, please feel free to ask the contributors.

• Vaughn Vernon, Book author and reviewer.
• Rinat Abdullin, A+ES text and this sample project. Tech Leader at Lokad, Big Data Analytics for Retail.
• Gregory Young, theory and practice of introducing Event Sourcing to Domain-Driven Design.

This sample is based hugely on inspiration and support provided by following outstanding gentlemen:

• Eric Evans - father of Domain-Driven Design
• Jérémie Chassaing - Event Sourcing practitioner from Paris. F# Maniac that built functional ES sample.
• Yves Reynhout - DDD and ES practitioner from Belgium, with really deep understanding.
• DDD/CQRS Google Group

As for bugs in the code and typos in the accompanying texts, please feel free to attribute them to Rinat Abdullin. Reporting them (e.g. by dropping me a tweet or an email) would be extra cool :)