CQRS & Event-Sourcing Framework for Go.

Last update: Dec 27, 2022

Comments: 17

goes - Event-Sourcing Framework

goes is a collection of interfaces, tools, and backend implementations that allow you to write event-sourced applicatios in Go.

If you have any questions or feedback, feel free to open an issue or start a discussion.

Getting Started

Installation

goes is not yet versioned because the API still changes too often. Install using a specific commit hash and make sure to install nested modules with /...

go get github.com/modernice/goes/...@<commit-hash>

Examples

To-Do App

Introduction

This documentation assumes knowledge of CQRS, event-sourcing, and other related concepts. Please make yourself familiar with these before reading further.

Features

Event Store Implementations (In-Memory, MongoDB)
Distributed Event Bus (NATS Core / NATS JetStream)
Distributed, event-driven Command Bus
Aggregate Framework
Projection Framework
SAGAs
Pre-built Modules
- Authorization Module

Components

goes provides incrementally adoptable components that together form a complete framework for building event-sourced applications. Read a component's README for a guide on how to use it.

Backends

Event Bus

Event Store

Contributing

TBD

License

Apache License, Version 2.0

Owner

modernice.design

https://github.com/modernice/goes

Comments

Review projection APIs

This issue will determine if the different projection APIs are even necessary to solve common problems or if there are better solutions to these problems that don't require these APIs.

HistoryDependent

The HistoryDependent API is used by projection jobs to determine which events a projection needs to properly update itself. If a projection implements HistoryDependent, it can hint to a projection job that it requires the full history of the events that are configured in the job, instead of just the (published) events that triggered the job.

ProgressAware

The ProgressAware API is usually used by persistent projections that are stored in a database. When a projection job is triggered, the application fetches the current projection state from the database, applies the events on it and saves it back to the database. A ProgressAware projection keeps track of the last applied event in terms of the event time, to ensure that no event is applied twice to the projection.
chore(deps): bump go.mongodb.org/mongo-driver from 1.10.3 to 1.10.4
Bumps go.mongodb.org/mongo-driver from 1.10.3 to 1.10.4.

Commits

29dffaf Update version to v1.10.4

861364b GODRIVER-2620 Fix hostname parsing for SRV polling. (#1112)

5762c6a GODRIVER-2543 Run make fmt with the latest Go version. #1065

2855941 GODRIVER-2565 Abort transaction before CommitLoop if context errored. (#1101)

3f59691 Update version to v1.10.4-prerelease

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Automated lookups

package user

const Aggregate = "user"
const NameLookup = "name"
const EmailLookup = "email"

const CreatedEvent = "user.created"

type CreatedData struct {
  Name string
  Email string
}

func (evt Created) ProvideLookup(p lookup.Provider)  {
  p.Provide(Aggregate, NameLookup, evt.Name)
  p.Provide(Aggregate, EmailLookup, evt.Email)
}

// somewhere else

var ctx context.Context

var store event.Store
l := lookup.New(store, Created) // create lookup from events in event store

errs, err := l.Run(ctx) // run the lookup projection

var aggregateID uuid.UUID

userID, err := l.Lookup(ctx, Aggregate, EmailLookup, "[email protected]")

only allows string values or use interface{}?
reverse lookups?

chore(deps): bump github.com/nats-io/nats.go from 1.22.0 to 1.22.1
Bumps github.com/nats-io/nats.go from 1.22.0 to 1.22.1.

Release notes

Sourced from github.com/nats-io/nats.go's releases.

Release v1.22.1

Changelog

Changed

Service API:

Monitoring subjects for a service are no longer uppercase (#1166)

Changed RequestHandler signature to no longer return an error (#1166)

Complete Changes

https://github.com/nats-io/nats.go/compare/v1.22.0...v1.22.1

Commits

6600948 Release v1.22.1 (#1168)

e350a6f [CHANGED] Service API adjustments (#1166)

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chore(deps): bump github.com/nats-io/nats.go from 1.21.0 to 1.22.0
Bumps github.com/nats-io/nats.go from 1.21.0 to 1.22.0.

Release notes

Sourced from github.com/nats-io/nats.go's releases.

Release v1.22.0

Changelog

Overview

This release adds a beta implementation of micro package, which provides API for creating and monitoring microservices on top of NATS connection.

Added

Service API beta implementation (#1160)

Getters for connection callbacks (#1162)

Complete Changes

https://github.com/nats-io/nats.go/compare/v1.21.0...v1.22.0

Commits

61a9345 Release v1.22.0 (#1165)

32b9daa [ADDED] Service api improvements (#1160)

95a7e50 [ADDED] Getters for connection callbacks (#1162)

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chore(deps): bump go.mongodb.org/mongo-driver from 1.11.0 to 1.11.1
Bumps go.mongodb.org/mongo-driver from 1.11.0 to 1.11.1.

Release notes

Sourced from go.mongodb.org/mongo-driver's releases.

MongoDB Go Driver 1.11.1

The MongoDB Go Driver Team is pleased to release version 1.11.1 of the official Go driver.

Release Notes

This release contains a bug fix for heartbeat buildup with streaming protocol when the Go driver process is paused in an FAAS environment (e.g. AWS Lambda). This release also includes a bug fix for handling sequential "NoWritesPerformed" labeled operation errors, in that they should still return the "previous indefinite error".

P.S. We want to hear about how Go developers use MongoDB and the MongoDB Go Driver! If you haven't already, please take the 2022 MongoDB Go Developer Survey.

For a full list of tickets included in this release, please see the links below:

Improvements

Bugs

Documentation for the Go driver can be found on pkg.go.dev and the MongoDB documentation site. BSON library documentation is also available on pkg.go.dev. Questions and inquiries can be asked on the MongoDB Developer Community. Bugs can be reported in the Go Driver project in the MongoDB JIRA where a list of current issues can be found. Your feedback on the Go driver is greatly appreciated!

Commits

88c138b Update version to v1.11.1

1f525ec Merge branch 'release/1.11' of github.com:mongodb/mongo-go-driver into releas...

fc7ebbb Revert "Release/1.11 (#1146)"

bf833d5 Release/1.11 (#1146)

cd79115 resolve merge conflicts

ed484be GODRIVER-2577 Retry heartbeat on timeout to prevent pool cleanup in FAAS paus...

30805e4 GODRIVER-2333 Assert that Ping op succeeds initial DNS spec tests (#1124)

19f3fb9 GODRIVER-2651 Break NoWritesPerformed-Only Error Sequence (#1135)

4803b59 Update version to v1.11.1-prerelease

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chore(deps): bump github.com/nats-io/nats.go from 1.20.0 to 1.21.0
Bumps github.com/nats-io/nats.go from 1.20.0 to 1.21.0.

Release notes

Sourced from github.com/nats-io/nats.go's releases.

Release v1.21.0

Changelog

Added

ConnectHandler connect option to detect that initial connection was established. This is especially useful when combined with RetryOnFailedConnect (#1133 )

IgnoreAuthErrorAbort connect option to prevent aborting reconnect attempts after receiving the same authentication error twice (#1141)

SkipTLSHandshake option to CustomDialer. SkipTLSHandshake method can be implemented on a custom dialer to prevent TLS handshake if not needed (#1147)

KV:

Return ErrKeyExists error when attempting to Create() a KV pair for an existing key (#1135, #1136)

JetStream:

Add ErrLeadershipChanged error, returned when consumer leadership has changed during a pull request on a consumer. Thanks to @sata-form3 for the contribution (#1151)

Improved

Remove deprecated usages of io/ioutil. Thanks to @cesarvspr for the contribution (#1150)

Remove experimental notice from KV implementation (#1154)

Complete Changes

https://github.com/nats-io/nats.go/compare/v1.20.0...v1.21.0

Commits

6c6add8 Release v1.21.0 (#1156)

7ca331a chore: remove deprecated usage of "io/ioutil" (#1150)

8241797 Remove experimental notice from KeyValue (#1154)

af3503a Merge pull request #1151 from sata-form3/sata-create-consumer-leadership-chan...

b2ad744 PR Review feedback

a52a9ec Provide a way to handle 409 Leadership Changed errors in client

907b219 Merge pull request #1147 from nats-io/custom-dialer-skip-tls

65b7870 Add SkipTLSHandshake small interface to CustomDialer

c9b2fd8 This adds an option to skip the TLS connection wrapper

398a1ec [ADDED] IgnoreAuthErrorAbort option on Connect (#1141)

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chore(deps): bump google.golang.org/grpc from 1.50.1 to 1.51.0
Bumps google.golang.org/grpc from 1.50.1 to 1.51.0.

Release notes

Sourced from google.golang.org/grpc's releases.

Release 1.51.0

Behavior Changes

xds: NACK EDS resources with duplicate addresses in accordance with a recent spec change (#5715)

Special Thanks: @erni27

grpc: restrict status codes that can be generated by the control plane (gRFC A54) (#5653)

New Features

client: set grpc-accept-encoding header with all registered compressors (#5541)

Special Thanks: @jronak

xds/weightedtarget: return a more meaningful error when all child policies are in TRANSIENT_FAILURE (#5711)

gcp/observability: add "started rpcs" metric (#5768)

xds: de-experimentalize the google-c2p-resolver (#5707)

balancer: add experimental Producer types and methods (#5669)

orca: provide a way for LB policies to receive OOB load reports (#5669)

Bug Fixes

go.mod: upgrade x/text dependency to address CVE 2022-32149 (#5769)

client: fix race that could lead to an incorrect connection state if it was closed immediately after the server's HTTP/2 preface was received (#5714)

Special Thanks: @fuweid

xds: ensure sum of the weights of all EDS localities at the same priority level does not exceed uint32 max (#5703)

Special Thanks: @erni27

client: fix binary logging bug which logs a server header on a trailers-only response (#5763)

balancer/priority: fix a bug where unreleased references to removed child policies (and associated state) was causing a memory leak (#5682)

xds/google-c2p: validate URI schema for no authorities (#5756)

Commits

eeb9afa Change version to 1.51.0 (#5782)

72812fe gcp/observability: filter logging from cloud ops endpoints calls (#5765)

0ae33e6 xdsclient: remove unused test code (#5772)

824f449 go.mod: upgrade x/text to v0.4 to address CVE (#5769)

7f23df0 xdsclient: switch xdsclient watch deadlock test to e2e style (#5697)

32f969e o11y: Added started rpc metric in o11y plugin (#5768)

b597a8e xdsclient: improve authority watchers test (#5700)

e41e894 orca: create ORCA producer for LB policies to use to receive OOB load reports...

36d14db Fix binary logging bug which logs a server header on a trailers only response...

fcb8bdf xds/google-c2p: validate url for no authorities (#5756)

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chore(deps): bump github.com/nats-io/nats.go from 1.19.1 to 1.20.0
Bumps github.com/nats-io/nats.go from 1.19.1 to 1.20.0.

Release notes

Sourced from github.com/nats-io/nats.go's releases.

Release v1.20.0

Changelog

Changed

JetStream:

[BREAKING CHANGE] Extract nats: Consumer Deleted server error to ErrConsumerDeleted variable. This error is returned when consumer is deleted while waiting on pull request and was introduced in nats-server v2.9.6 (#1125)

Improved

JetStream:

Fix broken comments on ErrConsumerNameAlreadyInUse and StreamNameBySubject(). Thanks to @subtle-byte for the contribution (#1128)

Core NATS:

Improve comment on RetryOnFailedConnect connect option (#1127)

Complete Changes

https://github.com/nats-io/nats.go/compare/v1.19.1...v1.20.0

Commits

5c57d4b Release v1.20.0 (#1129)

d80925c Fix some comments (#1128)

4d7d951 [ADDED] Extract ErrConsumerDeleted in Fetch() (#1125)

be36353 [IMPROVED] Comment on RetryOnFailedConnect (#1127)

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chore(deps): bump github.com/nats-io/nats.go from 1.19.0 to 1.19.1
Bumps github.com/nats-io/nats.go from 1.19.0 to 1.19.1.

Release notes

Sourced from github.com/nats-io/nats.go's releases.

Release v1.19.1

Changelog

Added

JetStream:

Expose StreamNameBySubject method on JetStreamContext interface for looking up stream by subject (#1114)

Return stream alternates when fetching stream info (#1118)

Changed

KV:

Use BindStream for watcher so it works with mirrors (#1116)

Fixed

KV:

Delete key not working correctly across mirrors (#1115)

Complete Changes

https://github.com/nats-io/nats.go/compare/v1.19.0...v1.19.1

Commits

980f955 Release v1.19.1 (#1123)

fbeee79 Merge pull request #1118 from nats-io/stream-alternates

6bd7837 Support stream alternates

e227e17 Merge pull request #1116 from nats-io/kv-mirror-watcher

416c895 Use BindStream for watcher so it works with mirrors.

48285d7 Merge pull request #1115 from nats-io/kv-mirror-fix-delete

7ac1087 [CHANGED] Make lookupStreamBySubject public (#1114)

9d7afb4 [FIX] KV delete not working correctly accross mirrors

6e4828a Merge pull request #1113 from nats-io/release/v1.19.0

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chore(deps): bump go.mongodb.org/mongo-driver from 1.10.3 to 1.11.0
Bumps go.mongodb.org/mongo-driver from 1.10.3 to 1.11.0.

Release notes

Sourced from go.mongodb.org/mongo-driver's releases.

MongoDB Go Driver 1.10.4

The MongoDB Go Driver Team is pleased to release version 1.10.4 of the official Go driver.

Release Notes

This release contains several bugfixes. One of the bugfixes removes a severe bug in SRV polling which may prevent changes in SRV records from updating the servers that the Go Driver attempts to connect to when the MongoDB connection string includes a username and password.

For a full list of tickets included in this release, please see the links below:

Bugs

Tasks

Documentation for the Go driver can be found on pkg.go.dev and the MongoDB documentation site. BSON library documentation is also available on pkg.go.dev. Questions and inquiries can be asked on the MongoDB Developer Community. Bugs can be reported in the Go Driver project in the MongoDB JIRA where a list of current issues can be found. Your feedback on the Go driver is greatly appreciated!

Commits

ea2a55c Update version to v1.11.0

1123dac GODRIVER-1530 GODRIVER-1213 Fix the enterprise auth test runner. (#1118)

7586dd7 GODRIVER-2621 use batchtime for fuzz tests (#1117)

9567271 GODRIVER-2631 - Always close internal.DefaultHTTPClient on Client.Disconnect ...

4a22ce6 GODRIVER-2050 - Add settable http.Clients and gracefully close provided defau...

edfc51c GODRIVER-2565 Abort transaction before CommitLoop if context errored. (#1101)

e4853fb GODRIVER-2620 Fix hostname parsing for SRV polling. (#1112)

f5312df GODRIVER-2487 No useMultipleMongoses false in findOneAndUpdate errorResponse ...

423be54 GODRIVER-2174 Bump minimum Go version to 1.13. (#1100)

39194dd GODRIVER-2604 Add ErrServerSelectionTimeout and WaitQueueTimeoutError to ...

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Google PubSub backend implementation for the event.Bus

Summary

Provide an Event Bus backend implementation backed by Google PubSub event broker.

Motivation

We are deploying our application GCE and we need an event bus to publish events so the application can use an event driven architecture. One of the uses is as for Event Sourcing and to allow the projectors to see events from aggregates.

We evaluated Google PubSub and saw that it supports Event Ordering. An event can provide an Ordering Key and the infrastructure will warrant the events for the same Ordering Key will be provided in order. Our intent is to use the Aggregate ID as the ordering key.

Proposal

The idea is to implement the event.Bus interface using the cloud.google.com/go/pubsub package. This implementation will take the nats.bus implementation as a base.

Using topicFunc (like subjectFunc in nats implementation), all events of a given aggregate type can be published on the same PubSub topic.

Also the Aggregate ID in the event can be used as an Ordering Key.

Note

I'm using this implementation to learn about goes and its capabilities. Any suggestion or guidence us wellcome.

Query Cache

Implement a flexible cache for event queries.

Features

Automatic cache key based on the query filters
Time-based and manual expiry
Optional cache storage

Examples

Basic usage

package example

import (
  "github.com/modernice/goes/event"
  "github.com/modernice/goes/event/query"
)

func example(store event.Store, q event.Query) {
  cache := query.NewCache(store)

  result, err := cache.Result(context.TODO(), q)
  // handle err

  if result.Cached {
    log.Println("cache returned cached result")
  } else {
    log.Println("cache executed query")
  }

  events, err := streams.Drain(context.TODO(), result.Events, result.Errs)
  // handle err

  // alternatively

  str, errs, err := cache.Run(context.TODO(), q)
  // handle err

  events, err := streams.Drain(context.TODO(), str, errs)
}

[contrib/auth] Add `QueryClient.Roles()` method

Allow querying of user roles:

package example

func example(client auth.QueryClient) {
  userID := uuid.New()
  roleIDs, roleNames, err := client.RolesOf(context.TODO(), userID)
}

Projection finalizers

Currently, projection finalization is implemented like this:

package example

type Foo struct { ... }

func (*Foo) ApplyEvent(event.Event) {}

func (f *Foo) finalize(ctx context.Context, dep SomeDependency) error {
  // do stuff
  if err := dep.Do(ctx, "..."); err != nil {
    return err
  }
  // do more stuff
  return nil
}

func example(s projection.Schedule) {
  var dep SomeDependency

  s.Subscribe(context.TODO(), func(ctx projection.Job) error {
    refs, errs, err := ctx.Aggregates(ctx)
    if err != nil {
      return fmt.Errorf("extract aggregates: %w", err)
    }

    return streams.Walk(ctx, func(ref aggregate.Ref) error {
      foo := NewFoo(ref.ID)

      if err := ctx.Apply(ctx, foo); err != nil {
        return err
      }

      return foo.finalize(ctx, dep)
    }, refs, errs)
  })
}

Finalization is done for each individual projection after the job applies its events. A nice addition would be if finalization could be batched and deferred to the end of the projection job, like this:

package example

func example(s projection.Schedule) {
  var dep SomeDependency

  s.Subscribe(context.TODO(), func(ctx projection.Job) error {
    refs, errs, err := ctx.Aggregates(ctx)
    if err != nil {
      return fmt.Errorf("extract aggregates: %w", err)
    }

    return streams.Walk(ctx, func(ref aggregate.Ref) error {
      foo := NewFoo(ref.ID)

      if err := ctx.Apply(ctx, foo); err != nil {
        return err
      }

      return ctx.Defer(func() error {
        // this call will be deferred to after this projection update
        return foo.finalize(ctx, dep)
      })
    }, refs, errs)
  })
}

Concurrent command handling

Add options to enable concurrent command handling.

Standalone command handler

package example

func example(bus command.Bus) {
  h := command.NewHandler(bus)

  h.Handle(context.TODO(), "foo", func(ctx command.Context) error { ... }, command.Workers(4))
}

Aggregate-based command handler

package example

type Foo struct {
  *aggregate.Base
  *handler.BaseHandler
}

func NewFoo(id uuid.UUID) *Foo { ... }

func example(bus command.Bus, repo aggregate.Repository) {
  h := handler.New(NewFoo, repo, bus)

  h.Handle(context.TODO(), command.Workers(4))
}

How to use `SoftRestorer`?

Problem

When the event stream of an aggregate contains a SoftDeleter event, the aggregate can neither be queried nor fetched from the aggregate repository. How can an aggregate be restored if it cannot be fetched to raise the SoftRestorer event?

Example

package example

type RestoredEvent struct {}

func (RestoredEvent) SoftRestore() bool { return true }

func example(repo aggregate.Repository) {
  var foo aggregate.Aggregate // soft-deleted aggregate

  if err := repo.Fetch(context.TODO(), foo); err != nil {
    // fails with repository.ErrDeleted
  }

  // we want to do this
  aggregate.Next(foo, "restored", RestoredEvent{})
  repo.Save(context.TODO(), foo)
}

Proposal – `context.Context` API

The repository package could provide a "hidden" API using context.Context.WithValue() to disable soft-deletion checks:

package example

func example(repo aggregate.Repository) {
  var foo aggregate.Aggregate

  ctx := repository.WithSoftDeleted(context.TODO())

  repo.Fetch(ctx, foo)
  aggregate.Next(foo, "restored", RestoredEvent{})
  repo.Save(context.TODO(), foo)
}

Drawbacks

hiding options behind a Context is considered bad design

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CQRS & Event-Sourcing Framework for Go.

goes - Event-Sourcing Framework

Getting Started

Installation

Examples

Introduction

Features

Components

Backends

Event Bus

Event Store

Contributing

License

Owner

modernice.design

Comments

Review projection APIs

HistoryDependent

ProgressAware

chore(deps): bump go.mongodb.org/mongo-driver from 1.10.3 to 1.10.4

Automated lookups

chore(deps): bump github.com/nats-io/nats.go from 1.22.0 to 1.22.1

Release v1.22.1

Changelog

Changed

Complete Changes

chore(deps): bump github.com/nats-io/nats.go from 1.21.0 to 1.22.0

Release v1.22.0

Changelog

Overview

Added

Complete Changes

chore(deps): bump go.mongodb.org/mongo-driver from 1.11.0 to 1.11.1

MongoDB Go Driver 1.11.1

Release Notes

chore(deps): bump github.com/nats-io/nats.go from 1.20.0 to 1.21.0

Release v1.21.0

Changelog

Added

Improved

Complete Changes

chore(deps): bump google.golang.org/grpc from 1.50.1 to 1.51.0

Release 1.51.0

Behavior Changes

New Features

Bug Fixes

chore(deps): bump github.com/nats-io/nats.go from 1.19.1 to 1.20.0

Release v1.20.0

Changelog

Changed

Improved

Complete Changes

chore(deps): bump github.com/nats-io/nats.go from 1.19.0 to 1.19.1

Release v1.19.1

Changelog

Added

Changed

Fixed

Complete Changes

chore(deps): bump go.mongodb.org/mongo-driver from 1.10.3 to 1.11.0

MongoDB Go Driver 1.10.4

Release Notes

Google PubSub backend implementation for the event.Bus

Summary

Motivation

Proposal

Note

Query Cache

Features

Examples

Basic usage

[contrib/auth] Add `QueryClient.Roles()` method

Projection finalizers

Concurrent command handling

Standalone command handler

Aggregate-based command handler

How to use `SoftRestorer`?

Problem

Example

Proposal – context.Context API

Proposal – `context.Context` API