func Example() {
// Support Wercker testing with MongoDB.
host := os.Getenv("MONGO_PORT_27017_TCP_ADDR")
port := os.Getenv("MONGO_PORT_27017_TCP_PORT")
url := "localhost"
if host != "" && port != "" {
url = host + ":" + port
}
// Create the event store.
eventStore, err := eventstore.NewEventStore(url, "demo")
if err != nil {
log.Fatalf("could not create event store: %s", err)
}
// Create the event bus that distributes events.
eventBus := eventbus.NewEventBus()
eventBus.AddObserver(&domain.Logger{})
// Create the aggregate repository.
repository, err := eh.NewEventSourcingRepository(eventStore, eventBus)
if err != nil {
log.Fatalf("could not create repository: %s", err)
}
// Create the aggregate command handler.
handler, err := eh.NewAggregateCommandHandler(repository)
if err != nil {
log.Fatalf("could not create command handler: %s", err)
}
// Register the domain aggregates with the dispather. Remember to check for
// errors here in a real app!
handler.SetAggregate(domain.InvitationAggregateType, domain.CreateInviteCommand)
handler.SetAggregate(domain.InvitationAggregateType, domain.AcceptInviteCommand)
handler.SetAggregate(domain.InvitationAggregateType, domain.DeclineInviteCommand)
// Create the command bus and register the handler for the commands.
commandBus := commandbus.NewCommandBus()
commandBus.SetHandler(handler, domain.CreateInviteCommand)
commandBus.SetHandler(handler, domain.AcceptInviteCommand)
commandBus.SetHandler(handler, domain.DeclineInviteCommand)
// Create and register a read model for individual invitations.
invitationRepository, err := readrepository.NewReadRepository(url, "demo", "invitations")
if err != nil {
log.Fatalf("could not create invitation repository: %s", err)
}
invitationRepository.SetModel(func() interface{} { return &domain.Invitation{} })
invitationProjector := domain.NewInvitationProjector(invitationRepository)
eventBus.AddHandler(invitationProjector, domain.InviteCreatedEvent)
eventBus.AddHandler(invitationProjector, domain.InviteAcceptedEvent)
eventBus.AddHandler(invitationProjector, domain.InviteDeclinedEvent)
// Create and register a read model for a guest list.
eventID := eh.NewUUID()
guestListRepository, err := readrepository.NewReadRepository(url, "demo", "guest_lists")
if err != nil {
log.Fatalf("could not create guest list repository: %s", err)
}
guestListRepository.SetModel(func() interface{} { return &domain.GuestList{} })
guestListProjector := domain.NewGuestListProjector(guestListRepository, eventID)
eventBus.AddHandler(guestListProjector, domain.InviteCreatedEvent)
eventBus.AddHandler(guestListProjector, domain.InviteAcceptedEvent)
eventBus.AddHandler(guestListProjector, domain.InviteDeclinedEvent)
// Clear DB collections.
eventStore.Clear()
invitationRepository.Clear()
guestListRepository.Clear()
// Issue some invitations and responses.
// Note that Athena tries to decline the event, but that is not allowed
// by the domain logic in InvitationAggregate. The result is that she is
// still accepted.
athenaID := eh.NewUUID()
commandBus.HandleCommand(&domain.CreateInvite{InvitationID: athenaID, Name: "Athena", Age: 42})
commandBus.HandleCommand(&domain.AcceptInvite{InvitationID: athenaID})
err = commandBus.HandleCommand(&domain.DeclineInvite{InvitationID: athenaID})
if err != nil {
log.Printf("error: %s\n", err)
}
hadesID := eh.NewUUID()
commandBus.HandleCommand(&domain.CreateInvite{InvitationID: hadesID, Name: "Hades"})
commandBus.HandleCommand(&domain.AcceptInvite{InvitationID: hadesID})
zeusID := eh.NewUUID()
commandBus.HandleCommand(&domain.CreateInvite{InvitationID: zeusID, Name: "Zeus"})
commandBus.HandleCommand(&domain.DeclineInvite{InvitationID: zeusID})
// Read all invites.
invitations, _ := invitationRepository.FindAll()
for _, i := range invitations {
if i, ok := i.(*domain.Invitation); ok {
log.Printf("invitation: %s - %s\n", i.Name, i.Status)
fmt.Printf("invitation: %s - %s\n", i.Name, i.Status)
}
}
// Read the guest list.
l, _ := guestListRepository.Find(eventID)
if l, ok := l.(*domain.GuestList); ok {
log.Printf("guest list: %d guests (%d accepted, %d declined)\n",
l.NumGuests, l.NumAccepted, l.NumDeclined)
fmt.Printf("guest list: %d guests (%d accepted, %d declined)\n",
l.NumGuests, l.NumAccepted, l.NumDeclined)
}
// records := eventStore.FindAllEventRecords()
// fmt.Printf("event records:\n")
// for _, r := range records {
// fmt.Printf("%#v\n", r)
// }
// Output:
// invitation: Athena - accepted
// invitation: Hades - accepted
// invitation: Zeus - declined
// guest list: 3 guests (2 accepted, 1 declined)
}
// Run runs the test scenario with the given EventStore and CommandBus.
// EventStores and ReadRepositories are created as needed with the given functions.
func Run(eventBus eventhorizon.EventBus, commandBus eventhorizon.CommandBus,
newEventStore NewEventStoreFunc,
newReadRepository NewReadRepositoryFunc) {
eventBus.AddGlobalHandler(&loggerSubscriber{})
if remoteEventBus, ok := eventBus.(eventhorizon.RemoteEventBus); ok {
fmt.Println("event registered")
remoteEventBus.RegisterEventType(&InviteCreated{}, func() eventhorizon.Event { return &InviteCreated{} })
remoteEventBus.RegisterEventType(&InviteAccepted{}, func() eventhorizon.Event { return &InviteAccepted{} })
remoteEventBus.RegisterEventType(&InviteDeclined{}, func() eventhorizon.Event { return &InviteDeclined{} })
defer remoteEventBus.Close()
}
if remoteCommandBus, ok := commandBus.(eventhorizon.RemoteCommandBus); ok {
fmt.Println("command registered")
remoteCommandBus.RegisterCommandType(&CreateInvite{}, func() eventhorizon.Command { return &CreateInvite{} })
remoteCommandBus.RegisterCommandType(&AcceptInvite{}, func() eventhorizon.Command { return &AcceptInvite{} })
remoteCommandBus.RegisterCommandType(&DeclineInvite{}, func() eventhorizon.Command { return &DeclineInvite{} })
defer remoteCommandBus.Close()
}
// Create the event store.
eventStore, err := newEventStore()
if err != nil {
log.Fatalf("could not create event store: %s", err)
}
if remoteEventStore, ok := eventStore.(eventhorizon.RemoteEventStore); ok {
remoteEventStore.RegisterEventType(&InviteCreated{}, func() eventhorizon.Event { return &InviteCreated{} })
remoteEventStore.RegisterEventType(&InviteAccepted{}, func() eventhorizon.Event { return &InviteAccepted{} })
remoteEventStore.RegisterEventType(&InviteDeclined{}, func() eventhorizon.Event { return &InviteDeclined{} })
remoteEventStore.Clear()
defer remoteEventStore.Close()
}
// Create the aggregate repository.
repository, err := eventhorizon.NewCallbackRepository(eventStore)
if err != nil {
log.Fatalf("could not create repository: %s", err)
}
// Register an aggregate factory.
repository.RegisterAggregate(&InvitationAggregate{},
func(id string) eventhorizon.Aggregate {
return &InvitationAggregate{
AggregateBase: eventhorizon.NewAggregateBase(id),
}
},
)
// Create the aggregate command handler.
handler, err := eventhorizon.NewAggregateCommandHandler(repository)
if err != nil {
log.Fatalf("could not create command handler: %s", err)
}
// Register the domain aggregates with the dispather. Remember to check for
// errors here in a real app!
handler.SetAggregate(&InvitationAggregate{}, &CreateInvite{})
handler.SetAggregate(&InvitationAggregate{}, &AcceptInvite{})
handler.SetAggregate(&InvitationAggregate{}, &DeclineInvite{})
// Create the command bus and register the handler for the commands.
commandBus.SetHandler(handler, &CreateInvite{})
commandBus.SetHandler(handler, &AcceptInvite{})
commandBus.SetHandler(handler, &DeclineInvite{})
// Create and register a read model for individual invitations.
invitationRepository, err := newReadRepository("invitations")
if err != nil {
log.Fatalf("could not create invitation repository: %s", err)
}
if remoteRepository, ok := invitationRepository.(eventhorizon.RemoteReadRepository); ok {
remoteRepository.SetModel(func() interface{} { return &Invitation{} })
remoteRepository.Clear()
defer remoteRepository.Close()
}
invitationProjector := NewInvitationProjector(invitationRepository)
eventBus.AddHandler(invitationProjector, &InviteCreated{})
eventBus.AddHandler(invitationProjector, &InviteAccepted{})
eventBus.AddHandler(invitationProjector, &InviteDeclined{})
// Create and register a read model for a guest list.
eventID := uuid.New()
guestListRepository, err := newReadRepository("guest_lists")
if err != nil {
log.Fatalf("could not create guest list repository: %s", err)
}
if remoteRepository, ok := guestListRepository.(eventhorizon.RemoteReadRepository); ok {
remoteRepository.SetModel(func() interface{} { return &GuestList{} })
remoteRepository.Clear()
defer remoteRepository.Close()
}
guestListProjector := NewGuestListProjector(guestListRepository, eventID)
eventBus.AddHandler(guestListProjector, &InviteCreated{})
eventBus.AddHandler(guestListProjector, &InviteAccepted{})
eventBus.AddHandler(guestListProjector, &InviteDeclined{})
// Issue some invitations and responses.
// Note that Athena tries to decline the event, but that is not allowed
// by the domain logic in InvitationAggregate. The result is that she is
// still accepted.
athenaID := uuid.New()
commandBus.PublishCommand(&CreateInvite{InvitationID: athenaID, EventID: eventID, Name: "Athena", Age: 42})
commandBus.PublishCommand(&AcceptInvite{InvitationID: athenaID})
err = commandBus.PublishCommand(&DeclineInvite{InvitationID: athenaID})
if err != nil {
fmt.Printf("error: %s\n", err)
}
hadesID := uuid.New()
commandBus.PublishCommand(&CreateInvite{InvitationID: hadesID, EventID: eventID, Name: "Hades"})
commandBus.PublishCommand(&AcceptInvite{InvitationID: hadesID})
zeusID := uuid.New()
commandBus.PublishCommand(&CreateInvite{InvitationID: zeusID, EventID: eventID, Name: "Zeus"})
commandBus.PublishCommand(&DeclineInvite{InvitationID: zeusID})
// TODO: Find a better way to ensure that all events were processed
time.Sleep(1 * time.Second)
// Read all invites.
invitations, _ := invitationRepository.FindAll()
for _, i := range invitations {
fmt.Printf("invitation: %#v\n", i)
}
// Read the guest list.
guestList, _ := guestListRepository.Find(eventID)
fmt.Printf("guest list: %#v\n", guestList)
}
func main() {
// Create the event bus that distributes events.
eventBus := eventhorizon.NewInternalEventBus()
eventBus.AddGlobalHandler(&LoggerSubscriber{})
// Create the event store.
eventStore, err := eventhorizon.NewMongoEventStore(eventBus, "localhost", "demo")
if err != nil {
log.Fatalf("could not create event store: %s", err)
}
eventStore.RegisterEventType(&InviteCreated{}, func() eventhorizon.Event { return &InviteCreated{} })
eventStore.RegisterEventType(&InviteAccepted{}, func() eventhorizon.Event { return &InviteAccepted{} })
eventStore.RegisterEventType(&InviteDeclined{}, func() eventhorizon.Event { return &InviteDeclined{} })
// Create the aggregate repository.
repository, err := eventhorizon.NewCallbackRepository(eventStore)
if err != nil {
log.Fatalf("could not create repository: %s", err)
}
// Register an aggregate factory.
repository.RegisterAggregate(&InvitationAggregate{},
func(id eventhorizon.UUID) eventhorizon.Aggregate {
return &InvitationAggregate{
AggregateBase: eventhorizon.NewAggregateBase(id),
}
},
)
// Create the aggregate command handler.
handler, err := eventhorizon.NewAggregateCommandHandler(repository)
if err != nil {
log.Fatalf("could not create command handler: %s", err)
}
// Register the domain aggregates with the dispather. Remember to check for
// errors here in a real app!
handler.SetAggregate(&InvitationAggregate{}, &CreateInvite{})
handler.SetAggregate(&InvitationAggregate{}, &AcceptInvite{})
handler.SetAggregate(&InvitationAggregate{}, &DeclineInvite{})
// Create the command bus and register the handler for the commands.
commandBus := eventhorizon.NewInternalCommandBus()
commandBus.SetHandler(handler, &CreateInvite{})
commandBus.SetHandler(handler, &AcceptInvite{})
commandBus.SetHandler(handler, &DeclineInvite{})
// Create and register a read model for individual invitations.
invitationRepository, err := eventhorizon.NewMongoReadRepository("localhost", "demo", "invitations")
if err != nil {
log.Fatalf("could not create invitation repository: %s", err)
}
invitationRepository.SetModel(func() interface{} { return &Invitation{} })
invitationProjector := NewInvitationProjector(invitationRepository)
eventBus.AddHandler(invitationProjector, &InviteCreated{})
eventBus.AddHandler(invitationProjector, &InviteAccepted{})
eventBus.AddHandler(invitationProjector, &InviteDeclined{})
// Create and register a read model for a guest list.
eventID := eventhorizon.NewUUID()
guestListRepository, err := eventhorizon.NewMongoReadRepository("localhost", "demo", "guest_lists")
if err != nil {
log.Fatalf("could not create guest list repository: %s", err)
}
guestListRepository.SetModel(func() interface{} { return &GuestList{} })
guestListProjector := NewGuestListProjector(guestListRepository, eventID)
eventBus.AddHandler(guestListProjector, &InviteCreated{})
eventBus.AddHandler(guestListProjector, &InviteAccepted{})
eventBus.AddHandler(guestListProjector, &InviteDeclined{})
// Clear DB collections.
eventStore.Clear()
invitationRepository.Clear()
guestListRepository.Clear()
// Issue some invitations and responses.
// Note that Athena tries to decline the event, but that is not allowed
// by the domain logic in InvitationAggregate. The result is that she is
// still accepted.
athenaID := eventhorizon.NewUUID()
commandBus.HandleCommand(&CreateInvite{InvitationID: athenaID, Name: "Athena", Age: 42})
commandBus.HandleCommand(&AcceptInvite{InvitationID: athenaID})
err = commandBus.HandleCommand(&DeclineInvite{InvitationID: athenaID})
if err != nil {
fmt.Printf("error: %s\n", err)
}
hadesID := eventhorizon.NewUUID()
commandBus.HandleCommand(&CreateInvite{InvitationID: hadesID, Name: "Hades"})
commandBus.HandleCommand(&AcceptInvite{InvitationID: hadesID})
zeusID := eventhorizon.NewUUID()
commandBus.HandleCommand(&CreateInvite{InvitationID: zeusID, Name: "Zeus"})
commandBus.HandleCommand(&DeclineInvite{InvitationID: zeusID})
// Read all invites.
invitations, _ := invitationRepository.FindAll()
for _, i := range invitations {
fmt.Printf("invitation: %#v\n", i)
}
// Read the guest list.
guestList, _ := guestListRepository.Find(eventID)
fmt.Printf("guest list: %#v\n", guestList)
// records := eventStore.FindAllEventRecords()
// fmt.Printf("event records:\n")
// for _, r := range records {
// fmt.Printf("%#v\n", r)
// }
}