org.wikimedia.eventutilities.core.event

Class EventStream

java.lang.Object

org.wikimedia.eventutilities.core.event.EventStream

public class EventStream
extends Object

Represents a single event stream. An event stream is a named continuous stream of events. An event is a well typed single datum with a specific timestamp. An event stream in Kafka is composed of 1 or more topics. This class uses Wikimedia specific event stream configuration and schema repositories to abstract looking up stream configuration, schemas, topics and canary events given a stream name.

Field Summary

Fields

Modifier and Type	Field and Description
protected EventSchemaLoader	eventSchemaLoader EventSchemaLoader instance used when getting a schema for this stream.
protected EventStreamConfig	eventStreamConfig EventStreamConfig instance used to lookup stream config settings for this stream.
protected String	streamName

Constructor Summary

Constructors

Constructor and Description
EventStream(String streamName, EventSchemaLoader eventSchemaLoader, EventStreamConfig eventStreamConfig) Consider using EventStreamFactory.createEventStream instead.

Method Summary

Modifier and Type	Method and Description
String	eventServiceName() Gets this EventStream's destination_event_service name.
URI	eventServiceUri() Returns the (discovery) URL to which events belonging to this EventStream should be POSTed.
URI	eventServiceUri(String datacenter) Returns the datacenter specific event service URL to which events belonging to this EventStream should be POSTed.
com.fasterxml.jackson.databind.node.ObjectNode	exampleEvent() Gets the schema for stream and returns the first element in its JSONSchema examples.
com.fasterxml.jackson.databind.node.ObjectNode	exampleEvent(String schemaVersion) Gets the schema for stream and returns the first element in its JSONSchema examples.
com.fasterxml.jackson.databind.JsonNode	getSetting(String settingName) Gets a setting from stream config for this stream.
String	latestSchemaId() Gets the $id from the latest schema.
String	latestSchemaVersion() Infers the latest schema version number from the schema's $id field.
protected com.fasterxml.jackson.databind.JsonNode	loadSchema(URI schemaUri) Loads the schema at the relative schemaUri using our eventSchemaLoader.
com.fasterxml.jackson.databind.JsonNode	messageKeyFields() Get the Kafka message key fields.
com.fasterxml.jackson.databind.JsonNode	schema() Infers the latest relative schemaUri for the stream from its schema_title stream config setting and fetches and returns the schema at that URI using eventSchemaLoader.
com.fasterxml.jackson.databind.JsonNode	schema(String version) Get the version relative schemaUri for the stream from its schema_title stream config setting and fetches and returns the schema at that URI using eventSchemaLoader.
String	schemaTitle() Gets the JSONSchema title configured for this EventStream.
URI	schemaUri() Builds a latest relative schema URI for stream based on WMF conventions.
URI	schemaUri(String version) Builds schema URI for stream based on WMF conventions.
String	streamName() Gets the stream name of this EventStream instance.
List<String>	topics() Gets the list of Kafka topics that compose this stream.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

streamName

protected String streamName

eventSchemaLoader

protected EventSchemaLoader eventSchemaLoader

EventSchemaLoader instance used when getting a schema for this stream.

eventStreamConfig

protected EventStreamConfig eventStreamConfig

EventStreamConfig instance used to lookup stream config settings for this stream.

Constructor Detail

EventStream

public EventStream(String streamName,
                   EventSchemaLoader eventSchemaLoader,
                   EventStreamConfig eventStreamConfig)

Consider using EventStreamFactory.createEventStream instead.

Method Detail

streamName

public String streamName()

Gets the stream name of this EventStream instance.

getSetting

public com.fasterxml.jackson.databind.JsonNode getSetting(String settingName)

Gets a setting from stream config for this stream.

topics

public List<String> topics()

Gets the list of Kafka topics that compose this stream.

eventServiceName

public String eventServiceName()

Gets this EventStream's destination_event_service name. This is an EventStreamConfig setting that should map to the event service URL where events of this stream can be POSTed.

eventServiceUri

public URI eventServiceUri()

Returns the (discovery) URL to which events belonging to this EventStream should be POSTed. E.g. https://eventgate-main.discovery.wmnet/v1/events

eventServiceUri

public URI eventServiceUri(String datacenter)

Returns the datacenter specific event service URL to which events belonging to this EventStream should be POSTed. E.g. https://eventgate-main.svc.eqiad.wmnet/v1/events This assumes that EventStreamConfig is configured locally here with a name to URI map of event_service_name-datacenter. If it isn't, this will return null.

messageKeyFields

public com.fasterxml.jackson.databind.JsonNode messageKeyFields()

Get the Kafka message key fields.

schemaTitle

public String schemaTitle()

Gets the JSONSchema title configured for this EventStream.

schemaUri

public URI schemaUri(String version)

Builds schema URI for stream based on WMF conventions. This expects that the stream's schema_title will easily map to a schema URI namespace hierarchy in a schema repository. E.g. schema_title: my/cool/schema and version 1.0.0 returns /my/cool/schema/1.0.0

Parameters:

version - version of the schema to load

schemaUri

public URI schemaUri()

Builds a latest relative schema URI for stream based on WMF conventions. This expects that the stream's schema_title will easily map to a schema URI namespace hierarchy in a schema repository. E.g. schema_title: my/cool/schema returns /my/cool/schema/latest

schema

public com.fasterxml.jackson.databind.JsonNode schema()

Infers the latest relative schemaUri for the stream from its schema_title stream config setting and fetches and returns the schema at that URI using eventSchemaLoader.

schema

public com.fasterxml.jackson.databind.JsonNode schema(String version)

Get the version relative schemaUri for the stream from its schema_title stream config setting and fetches and returns the schema at that URI using eventSchemaLoader.

Parameters:

version - version of the schema to load

latestSchemaId

public String latestSchemaId()

Gets the $id from the latest schema.

latestSchemaVersion

public String latestSchemaVersion()

Infers the latest schema version number from the schema's $id field.

loadSchema

protected com.fasterxml.jackson.databind.JsonNode loadSchema(URI schemaUri)

Loads the schema at the relative schemaUri using our eventSchemaLoader.

exampleEvent

public com.fasterxml.jackson.databind.node.ObjectNode exampleEvent()

Gets the schema for stream and returns the first element in its JSONSchema examples. If the schema does not have any examples, returns null.

exampleEvent

public com.fasterxml.jackson.databind.node.ObjectNode exampleEvent(String schemaVersion)

Gets the schema for stream and returns the first element in its JSONSchema examples. If the schema does not have any examples, returns null.

Parameters:

schemaVersion - the schemaVersion

toString

public String toString()

Overrides:

toString in class Object