events: implement package with memory & nats streams (#1942)

events/events.go

@@ -0,0 +1,46 @@
+// Package events contains interfaces for managing events within distributed systems
+package events
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+)
+
+var (
+	// ErrMissingTopic is returned if a blank topic was provided to publish
+	ErrMissingTopic = errors.New("Missing topic")
+	// ErrEncodingMessage is returned from publish if there was an error encoding the message option
+	ErrEncodingMessage = errors.New("Error encoding message")
+)
+
+// Stream of events
+type Stream interface {
+	Publish(topic string, opts ...PublishOption) error
+	Subscribe(opts ...SubscribeOption) (<-chan Event, error)
+}
+
+// Store of events
+type Store interface {
+	Read(opts ...ReadOption) ([]*Event, error)
+	Write(event *Event, opts ...WriteOption) error
+}
+
+// Event is the object returned by the broker when you subscribe to a topic
+type Event struct {
+	// ID to uniquely identify the event
+	ID string
+	// Topic of event, e.g. "registry.service.created"
+	Topic string
+	// Timestamp of the event
+	Timestamp time.Time
+	// Metadata contains the encoded event was indexed by
+	Metadata map[string]string
+	// Payload contains the encoded message
+	Payload []byte
+}
+
+// Unmarshal the events message into an object
+func (e *Event) Unmarshal(v interface{}) error {
+	return json.Unmarshal(e.Payload, v)
+}