eventstream

eventstream-go-sdk

Go SDK for integrating with AccelByte's event stream

Usage

Install

go get -u github.com/AccelByte/eventstream-go-sdk

Importing

eventstream "github.com/AccelByte/eventstream-go-sdk"

To create a new event stream client, use this function:

client, err := eventstream.NewClient(prefix, stream, brokers, config)

NewClient requires 4 parameters :

• prefix : Topic prefix from client (string)
• stream : Stream name. e.g. kafka, stdout, none (string)
• brokers : List of kafka broker (array of string)
• config : Custom broker configuration from client. This is optional and only uses the first arguments. (variadic *BrokerConfig)

Supported Stream

Currently event stream are supported by these stream:

Kafka Stream

Publish and subscribe an event to / from Kafka stream.

currently compatible with golang version from 1.12+ and Kafka versions from 0.10.1.0 to 2.1.0.

To create a kafka stream client, just pass the stream parameter with kafka.

Custom Configuration

SDK support with custom configuration for kafka stream, that is :

• DialTimeout : Timeout duration during connecting to kafka broker. Default: 10 Seconds (time.Duration)
• ReadTimeout : Timeout duration during consume topic from kafka broker. Default: 10 Seconds (time.Duration)
• WriteTimeout : Timeout duration during publish event to kafka broker. Default: 10 Seconds (time.Duration)
• LogMode : eventstream will print log based on following levels: info, warn, debug, error and off. Default: off (string)
• StrictValidation : If it set true, eventstream will enable strict validation for event fields, Default: False (boolean)

    config := &eventstream.BrokerConfig{
		LogMode:          eventstream.InfoLevel,
		StrictValidation: true,
		DialTimeout:      1 * time.Second,
		ReadTimeout:      1 * time.Second,
		WriteTimeout:     1 * time.Second,
	}

Stdout Stream

This stream is for testing purpose. This will print the event in stdout. It should not be used in production since this will print unnecessary log.

To create a stdout stream client, just pass the stream parameter with stdout.

Blackhole

This is used when client don't want the service to send event data to anywhere.

To create a blackhole client, just pass the stream parameter with none.

Publish Subscribe Event

Publish

Publish or sent an event into stream. Client able to publish an event into single or multiple topic. Publish to kafka stream support with exponential backoff retry. (max 3x)

To publish an event, use this function:

err := client.Publish(
		NewPublish().
			Topic(TopicName).
			EventName(EventName).
			Namespace(Namespace).
			ClientID(ClientID).
			UserID(UserID).
			SessionID(SessionID).
			TraceID(TraceID).
			SpanContext(SpanContext).
			Context(Context).
			EventID(eventID int).
			EventType(eventType int).
			EventLevel(eventLevel int).
			ServiceName(serviceName string).
			ClientIDs(clientIDs []string).
			TargetUserIDs(targetUserIDs []string).
			TargetNamespace(targetNamespace string).
			Privacy(privacy bool).
			AdditionalFields(additionalFields map[string]interface{}).
			Version(Version).
			Payload(Payload).
			ErrorCallback(func(event *Event, err error) {}))

Parameter

• Topic : List of topic / channel. (variadic string - alphaNumeric(256) - Required)
• EventName : Event name. (string - alphaNumeric(256) - Required) * Namespace : Event namespace. (string - alphaNumeric(256) - Required)
• ClientID : Publisher client ID. (string - UUID v4 without Hyphens)
• UserID : Publisher user ID. (string - UUID v4 without Hyphens)
• SessionID : Publisher session ID. (string - UUID v4 without Hyphens)
• TraceID : Trace ID. (string - UUID v4 without Hyphens)
• SpanContext : Opentracing Jaeger Span Context(string - optional)
• Context : Golang context. (context - default: context.background)
• Version : Version of schema. (integer - default: 1)
• EventID : Event ID. Backward compatibility. (integer)
• EventType : Event Type. Backward compatibility. (integer)
• EventLevel : Event Level. Backward compatibility. (integer)
• ServiceName : Service Name. Backward compatibility. (string)
• ClientIDs : List of client IDs. Backward compatibility. ([]string - UUID v4 without Hyphens)
• TargetUserIDs : List of target client IDs. Backward compatibility. ([]string - UUID v4 without Hyphens)
• TargetNamespace : Target Namespace. Backward compatibility. (string)
• Privacy : Privacy. Backward compatibility. (bool)
• AdditionalFields : Additional fields. Backward compatibility. (map[string]interface{})
• Payload : Additional attribute. (map[string]interface{})
• ErrorCallback : Callback function when event failed to publish. (func(event *Event, err error){})

Subscribe

To subscribe an event from specific topic in stream, client should be register a callback function that executed once event received. A callback aimed towards specific topic and event name.

To subscribe an event, use this function:

err := client.Register(
		NewSubscribe().
			Topic(topicName).
			EventName(mockEvent.EventName).
			GroupID(groupID).
			Context(ctx).
			Callback(func(ctx context.Context, event *Event, err error) {}))

Unsubscribe

To unsubscribe a topic from the stream, client should close passed context

To unsubscribe from the topic, use this function:

ctx, cancel := context.WithCancel(context.Background())

err := client.Register(
    NewSubscribe().
        Topic(topicName).
        EventName(mockEvent.EventName).
        GroupID(groupID).
        Context(ctx).
        Callback(func(ctx context.Context, event *Event, err error) {
            if ctx.Error() != nil {
                // unsubscribed
                return
            }           
        }))

cancel() // cancel context to unsubscribe

Parameter

• Topic : Subscribed topic. (string - alphaNumeric(256) - Required)
• EventName : Event name. (string - alphaNumeric(256) - Required)
• Namespace : Event namespace. (string - alphaNumeric(256) - Required)
• GroupID : Message broker group / queue ID. (string - alphaNumeric(256) - default: *)
• Context : Golang context. (context - default: context.background)
• Callback : Callback function when receive event. (func(ctx context.Context,event *Event, err error){} - required)

Callback function passing 3 parameters:

• ctx context to check that consumer unsubscribed
• event is object that store event message.
• err is an error that happen when consume the message.

Event Message

Event message is a set of event information that would be publish or consume by client.

Event message format :

• id : Event ID (string - UUID v4 without Hyphens)
• name : Event name (string)
• namespace : Event namespace (string)
• traceId : Trace ID (string - UUID v4 without Hyphens)
• spanContext : Opentracing Jaeger Span Context (string - optional)
• clientId : Publisher client ID (string - UUID v4 without Hyphens)
• userId : Publisher user ID (string - UUID v4 without Hyphens)
• sessionId : Publisher session ID (string - UUID v4 without Hyphens)
• timestamp : Event time (time.Time)
• event_id : Event id. backward compatibility. (integer)
• event_type : Event type. backward compatibility. (integer)
• event_level : Event level. backward compatibility. (integer)
• service : Service name. backward compatibility. (string)
• client_ids : Client IDs. backward compatibility. ([]string - UUID v4 without Hyphens)
• target_user_ids : Target user IDs. backward compatibility. ([]string - UUID v4 without Hyphens)
• target_namespace : Target namespace. backward compatibility. (string)
• privacy : Privacy. backward compatibility. (bool)
• additional_fields : Set of data / object that given by producer. Each data have own key for specific purpose. Backward compatibility. (map[string]interface{})
• version : Event schema version (integer)
• payload : Set of data / object that given by producer. Each data have own key for specific purpose. (map[string]interface{})

SpanContext usage

• Create Jaeger Span Context from an event

	import "github.com/AccelByte/go-restful-plugins/v3/pkg/jaeger"

    spanContextString := event.SpanContext
	span, ctx := jaeger.ChildSpanFromRemoteSpan(rootCtx, "service-name.operation-name", spanContextString)

• Put existing Jaeger Span Context into an event

	import "github.com/AccelByte/go-restful-plugins/v3/pkg/jaeger"

    spanContextString := jaeger.GetSpanContextString(span)
    
    err := client.Register(
        NewSubscribe().
            Topic(topicName).
            SpanContext(spanContextString).
            // ...