events

Documentation

Index

• type Callbacks
• type Capabilities
• type ChangeEventListener
• type Plugin
• type PluginAll
• type SubscriptionMatcher

Types

type Callbacks

type Callbacks interface {

	// RegisterConnection can be fired as often as requied.
	// Dispatchers will be started against this connection for all persisted subscriptions that match via the supplied function.
	// It can be fired multiple times for the same connection ID, to update the subscription list
	// For a "connect-out" style plugin (MQTT/AMQP/JMS broker), you might fire it at startup (from Init) for each target queue, with a subscription match
	// For a "connect-in" style plugin (inbound WebSocket connections), you fire it every time the client application connects attaches to a subscription
	RegisterConnection(connID string, matcher SubscriptionMatcher) error

	// EphemeralSubscription creates an ephemeral (non-durable) subscription, and associates it with a connection
	EphemeralSubscription(connID, namespace string, filter *fftypes.SubscriptionFilter, options *fftypes.SubscriptionOptions) error

	// ConnnectionClosed is a notification that a connection has closed, and all dispatchers should be re-allocated.
	// Note the plugin must not crash if it receives PublishEvent calls on the connID after the ConnectionClosed event is fired
	ConnnectionClosed(connID string)

	// DeliveryResponse responds to a previous event delivery, to either:
	// - Acknowledge it: the offset for the associated subscription can move forwards
	//   * Note all gaps must fill before the offset can move forwards, so this message might still be redelivered if streaming ahead
	//   * If a message is included in the response, then that will be automatically sent with the correct CID
	// - Reject it: This resets the associated subscription back to the last committed offset
	//   * Note all message since the last committed offet will be redelivered, so additional messages to be redelivered if streaming ahead
	DeliveryResponse(connID string, inflight *fftypes.EventDeliveryResponse)
}

type Capabilities

type Capabilities struct {
	// ChangeEvents is whether change events are supported
	ChangeEvents bool
}

type ChangeEventListener

type ChangeEventListener interface {
	// ChangeEvent delivers a change event - no ack for these
	ChangeEvent(connID string, ce *fftypes.ChangeEvent)
}

ChangeEventListener is an optional interface for delivering database change events, only supported for ephemeral connections

type Plugin

type Plugin interface {
	fftypes.Named

	// InitPrefix initializes the set of configuration options that are valid, with defaults. Called on all plugins.
	InitPrefix(prefix config.Prefix)

	// Init initializes the plugin, with configuration
	// Returns the supported featureset of the interface
	Init(ctx context.Context, prefix config.Prefix, callbacks Callbacks) error

	// Capabilities returns capabilities - not called until after Init
	Capabilities() *Capabilities

	// GetOptionsSchema returns a JSON schema for the transport specific options
	GetOptionsSchema(context.Context) string

	// ValidateOptions verifies a set of input options, prior to storage of a new subscription
	// The plugin can modify the core subscription options, such as overriding whether data is delivered.
	ValidateOptions(options *fftypes.SubscriptionOptions) error

	// DeliveryRequest requests delivery of work on a connection, which must later be responded to
	// Data will only be supplied as non-nil if the subscription is set to include data
	DeliveryRequest(connID string, sub *fftypes.Subscription, event *fftypes.EventDelivery, data []*fftypes.Data) error
}

Plugin is the interface implemented by event interface - Delivery to generic application code - WebSockets, Webhooks, AMQP etc. - Integration of frameworks for coordination of multi-party compute - Hyperledger Avalon, etc.

type PluginAll

type PluginAll interface {
	Plugin
	ChangeEventListener
}

PluginAll is a combined interface for easy mocking, with all optional features

type SubscriptionMatcher

type SubscriptionMatcher func(fftypes.SubscriptionRef) bool