README
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eh-outbox: An implementation of standard outbox pattern.
eh-outbox is the experimental driver of standard message outbox and message relay pattern which is useful to publish the domain events to external service as well as to preapare the different read views. It will help to decouple the write and read side, so even if readside service/db is down, still the write side will be operational.
Note: It is experimental driver and eventually will be merge to eventhorizon(https://github.com/looplab/eventhorizon) once it is stable enough.
Design:
Documentation
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Index ¶
- Constants
- Variables
- func AssignProjectorID(name string, offsetRepo *mongodb.Repo) int32
- func Reset(ctx context.Context, repoOutbox *mongodb.Repo, repoOffset *mongodb.Repo) error
- type DefaultConverter
- type EventOutbox
- type HoldOutboxEvent
- type IConverter
- type IOutbox
- type IProjector
- type ReadProjectorGroup
Constants ¶
const ( Stopped = 0 Paused = 1 Running = 2 )
Possible worker states.
Variables ¶
var ( // ErrInvalidEventData error returned when a events data is invalid ErrInvalidEventData = errors.New("Invalid Event data") // ErrConvertToExternalEvent error returned when converter fails to convert internal event to external event ErrConvertToExternalEvent = errors.New("Failed !! to convert to external event") // ErrSkipThisEvent error returned when custom converter skip this event, while pulishing to read side. ErrSkipThisEvent = errors.New("Info !! event skipped by converter implementation") // ErrProjectorNotInitialized error returned when a projector object not been initialized properly. ErrProjectorNotInitialized = errors.New("Error !! projector not initiallized") )
Functions ¶
func AssignProjectorID ¶
AssignProjectorID will assign a bit position to the concrete projector at the time of projector registration
Types ¶
type DefaultConverter ¶
type DefaultConverter struct {
}
DefaultConverter to publish the internal event as it is
func (*DefaultConverter) ConvertToExternalEvent ¶
func (d *DefaultConverter) ConvertToExternalEvent(ctx context.Context, event eh.Event) (interface{}, error)
ConvertToExternalEvent for defautlt converter
type EventOutbox ¶
type EventOutbox struct {
InProg int32 `json:"inProg" bson:"inProg"`
Done int32 `json:"done" bson:"done"`
EventType eh.EventType `json:"event_type" bson:"event_type"`
Data interface{} `json:"data" bson:"data"`
Timestamp time.Time `json:"timestamp" bson:"timestamp"`
}
EventOutbox is helper to write the events to outbox
func (*EventOutbox) SaveToOutbox ¶
func (eventOutbox *EventOutbox) SaveToOutbox(ctx context.Context, repo *mongodb.Repo, id interface{}, eventType eh.EventType) error
SaveToOutbox save events to outbox.
type HoldOutboxEvent ¶
type HoldOutboxEvent struct {
ID bson.ObjectId `json:"_id" bson:"_id,omitempty"`
InProg int32 `json:"inProg" bson:"inProg"`
Done int32 `json:"done" bson:"done"`
EventType eh.EventType `json:"event_type" bson:"event_type"`
Data interface{} `json:"data" bson:"data"`
Timestamp time.Time `json:"timestamp" bson:"timestamp"`
}
HoldOutboxEvent is helper to read scan events from outbox.
func (*HoldOutboxEvent) FindAndModify ¶
func (holdEvent *HoldOutboxEvent) FindAndModify(ctx context.Context, repo *mongodb.Repo, filter bson.M, change mgo.Change) error
FindAndModify to read a event from outbox follwing filter and change rules. Need ckt breaker to save db call incase there is no more event to be scan by projector
type IConverter ¶
type IConverter interface {
ConvertToExternalEvent(ctx context.Context, event eh.Event) (interface{}, error)
}
IConverter is to inject logic to convert internal to external event
type IOutbox ¶
type IOutbox interface {
FindAndModify(ctx context.Context, repo *mongodb.Repo, filter bson.M, change mgo.Change) error
}
IOutbox interface to scan events from outbox.
type IProjector ¶
type IProjector interface {
Name() string
Bit() int32
AssignProjectorID(offsetRepo *mongodb.Repo)
OutboxRepo() *mongodb.Repo
OffsetRepo() *mongodb.Repo
Converter() IConverter
WriteToReadside(ctx context.Context, key string, data interface{}) error
}
IProjector is the interface for all the projector
type ReadProjectorGroup ¶
type ReadProjectorGroup struct {
// contains filtered or unexported fields
}
ReadProjectorGroup is collection of iWorker
func GetReadProjectorGroup ¶
func GetReadProjectorGroup() *ReadProjectorGroup
GetReadProjectorGroup get the singleton object of ReadProjectorGroup
func (*ReadProjectorGroup) RegisterProjector ¶
func (rpg *ReadProjectorGroup) RegisterProjector(p IProjector)
RegisterProjector to register a new readside projector
func (*ReadProjectorGroup) Start ¶
func (rpg *ReadProjectorGroup) Start()
Start all the projector worker
Source Files
Directories