jacqueskang/eventsourcing

.NET Core event sourcing framework

eventsourcing's Issues

CQRS and Event Projection Samples

Examples for CQRS and Event Projection would make this library more completed.

support using Azure Cosmos DB as event store

TextFileSnapshotStore.FindLastSnapshotAsync crashes when unrelated snapshots are present

When there are aggregates with a snapshot, and you call the method FindAggregateAsync(id, ignoreSnapshots, version) with ignoreSnapshots set to false, the TextFileSnapshotStore.FindLastSnapshotAsync method fails.
The logic for getting the last snapshot of an aggregate doesn't check if the snapshot is for the relevant aggregate.

Event store should fire events that are used by external systems

Typical use of events published by event store are to maintain materialized views and integration with other systems.

Handling concurrency

Does this sample handle concurrency ?

Let's say I created a gift card with an initial value of 100 and executed two request at the same time to debit 40 points for the first request and 50 points for the second request.
I might end up with a gift card value of 60 or 50 after the two operations have been processed. Is this possible ?

Thanks in advance

Support using Azure Table Storage as event store

Support using AWS DynamoDB as event store

Great library! Should the DateTimes be changed to DateTimeOffset?

Wow! Thank you so much for developing this and making it publicly available. I only started researching event sourcing and CQRS this week, having looked at DDD more generally a few months back. Your library has been really educational in helping me understand the concepts and is starting to become useful now that I'm working through examples of my own.

One small point (maybe you think it's pedantic). Seeing as timestamps are so important to the auditability of the system, which could be deployed across servers (and accessed by clients) in different time-zones, shouldn't your DateTime objects be DateTimeOffset instead.

If I understand correctly, this is the standard recommended for most use cases by Microsoft:

The uses for DateTimeOffset values are much more common than those for DateTime values. As a result, consider DateTimeOffset as the default date and time type for application development.

https://docs.microsoft.com/en-us/dotnet/standard/datetime/choosing-between-datetime

Maybe I'm totally wrong, in which case, sorry. But if I'm right, it should be an easy fix, right?

Support rehydrating an entity at specific version

Update AggregateRepository.FindAggregateAsync() adding a new version parameter

Snapshots

Hi Jacques,

I recently stumbled upon your library when going through stackoverflow, and I must say I'm very impressed. Great work!

I was wondering whether you're planning to include snapshot capability to the library.

Cheers

What is the difference between Caching and Snapshot?

Great stuff here! Thanks :)

What is the difference between Caching and Snapshot?
I imagine snapshot is a kind of caching no;

Provide an abstract aggregate repository which supports distributed caching

TakeSnapshot Problem

Can provide option for TakeSnapshot method replace old snapshot rather than add new version snapshot

Hot to make the aggregate thread-safe (suggestions)?

As far as I understand the aggregates are not thread-safe.

I am looking to see how we could implement a thread-safe aggregate without introducing some distributed locking using DynamoDB or Redis.

An example scenario is if you have an ASP.NET REST API and consider the following endpoints for the same user aggregate invoked in parallel from a front end client it can result in weird results in event data (skipped version, dynamodb streams INSERT and MODIFY events writing the same aggregate ID and Version for different events).

1. /create
2. /set-email
3. /set-preferences
4. /set-profile-picture

Any ideas?