queues

package
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 Go to latest Published: Apr 4, 2021 License: MIT Imports: 9 Imported by: 0

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Types

type KafkaMessageQueue 

type KafkaMessageQueue struct {
	cqueues.MessageQueue

	//The dependency resolver.
	DependencyResolver *cref.DependencyResolver
	//The logger.
	Logger *clog.CompositeLogger
	//The Kafka connection component.
	Connection *connect.KafkaConnection
	// contains filtered or unexported fields
}

KafkaMessageQueue are message queue that sends and receives messages via Kafka message broker. 

Configuration parameters:

- topic: name of Kafka topic to subscribe - group_id: (optional) consumer group id (default: default) - from_beginning: (optional) restarts receiving messages from the beginning (default: false) - read_partitions: (optional) number of partitions to be consumed concurrently (default: 1) - autocommit: (optional) turns on/off autocommit (default: true) - connection(s):

  • discovery_key: (optional) a key to retrieve the connection from IDiscovery
  • host: host name or IP address
  • port: port number
  • uri: resource URI or connection string with all parameters in it

- credential(s):

  • store_key: (optional) a key to retrieve the credentials from ICredentialStore
  • username: user name
  • password: user password

- options:

  • autosubscribe: (optional) true to automatically subscribe on option (default: false)

  • acks (optional) control the number of required acks: -1 - all, 0 - none, 1 - only leader (default: -1)

  • log_level: (optional) log level 0 - None, 1 - Error, 2 - Warn, 3 - Info, 4 - Debug (default: 1)

  • connect_timeout: (optional) number of milliseconds to connect to broker (default: 1000)

  • max_retries: (optional) maximum retry attempts (default: 5)

  • retry_timeout: (optional) number of milliseconds to wait on each reconnection attempt (default: 30000)

  • request_timeout: (optional) number of milliseconds to wait on flushing messages (default: 30000)

    References:

- *:logger:*:*:1.0 (optional) ILogger components to pass log messages - *:counters:*:*:1.0 (optional) ICounters components to pass collected measurements - *:discovery:*:*:1.0 (optional) IDiscovery services to resolve connections - *:credential-store:*:*:1.0 (optional) Credential stores to resolve credentials - *:connection:kafka:*:1.0 (optional) Shared connection to Kafka service

See MessageQueue See MessagingCapabilities

Example: 

    queue := NewKafkaMessageQueue("myqueue")
    queue.Configure(cconf.NewConfigParamsFromTuples(
      "subject", "mytopic",
      "connection.protocol", "kafka"
      "connection.host", "localhost"
      "connection.port", 1883
    ))

    queue.open("123")

    queue.Send("123", NewMessageEnvelope("", "mymessage", "ABC"))

    message, err := queue.Receive("123")
	if (message != nil) {
		...
		queue.Complete("123", message);
	}

func NewKafkaMessageQueue 

func NewKafkaMessageQueue(name string) *KafkaMessageQueue

Creates a new instance of the queue component.

  • name (optional) a queue name.

func (*KafkaMessageQueue) Abandon 

func (c *KafkaMessageQueue) Abandon(message *cqueues.MessageEnvelope) error

Abandon method are returnes message into the queue and makes it available for all subscribers to receive it again. This method is usually used to return a message which could not be processed at the moment to repeat the attempt. Messages that cause unrecoverable errors shall be removed permanently or/and send to dead letter queue. Important: This method is not supported by Kafka. Parameters:

  • message *cqueues.MessageEnvelope a message to return.

Returns: error 

error or nil for success.

func (*KafkaMessageQueue) Cleanup 

func (c *KafkaMessageQueue) Cleanup(kafka.ConsumerGroupSession) error

Cleanup is run at the end of a session, once all ConsumeClaim goroutines have exited

func (*KafkaMessageQueue) Clear 

func (c *KafkaMessageQueue) Clear(correlationId string) error

Clear method are clears component state. Parameters:

  • correlationId string (optional) transaction id to trace execution through call chain.

Returns error or nil no errors occured.

func (*KafkaMessageQueue) Close 

func (c *KafkaMessageQueue) Close(correlationId string) (err error)

Closes component and frees used resources.

  • correlationId (optional) transaction id to trace execution through call chain.
  • Returns error or nil no errors occured.

func (*KafkaMessageQueue) Complete 

func (c *KafkaMessageQueue) Complete(message *cqueues.MessageEnvelope) error

Complete method are permanently removes a message from the queue. This method is usually used to remove the message after successful processing. Important: This method is not supported by Kafka. Parameters:

  • message *cqueues.MessageEnvelope a message to remove.

Returns: error error or nil for success.

func (*KafkaMessageQueue) Configure 

func (c *KafkaMessageQueue) Configure(config *cconf.ConfigParams)

Configures component by passing configuration parameters.

  • config configuration parameters to be set.

func (*KafkaMessageQueue) ConsumeClaim 

func (c *KafkaMessageQueue) ConsumeClaim(session kafka.ConsumerGroupSession, claim kafka.ConsumerGroupClaim) error

ConsumeClaim must start a consumer loop of ConsumerGroupClaim's Messages().

func (*KafkaMessageQueue) EndListen 

func (c *KafkaMessageQueue) EndListen(correlationId string)

EndListen method are ends listening for incoming messages. When this method is call listen unblocks the thread and execution continues. Parameters:

  • correlationId string (optional) transaction id to trace execution through call chain.

func (*KafkaMessageQueue) IsOpen 

func (c *KafkaMessageQueue) IsOpen() bool

Checks if the component is opened. Returns true if the component has been opened and false otherwise.

func (*KafkaMessageQueue) Listen 

func (c *KafkaMessageQueue) Listen(correlationId string, receiver cqueues.IMessageReceiver) error

Listens for incoming messages and blocks the current thread until queue is closed. Parameters:

  • correlationId string (optional) transaction id to trace execution through call chain.
  • receiver cqueues.IMessageReceiver a receiver to receive incoming messages.

See IMessageReceiver See receive

func (*KafkaMessageQueue) MoveToDeadLetter 

func (c *KafkaMessageQueue) MoveToDeadLetter(message *cqueues.MessageEnvelope) error

Permanently removes a message from the queue and sends it to dead letter queue. Important: This method is not supported by Kafka. Parameters:

  • message *cqueues.MessageEnvelope a message to be removed.

Returns: error 

error or nil for success.

func (*KafkaMessageQueue) OnMessage 

func (c *KafkaMessageQueue) OnMessage(msg *connect.KafkaMessage)

func (*KafkaMessageQueue) Open 

func (c *KafkaMessageQueue) Open(correlationId string) (err error)

Opens the component.

  • correlationId (optional) transaction id to trace execution through call chain.
  • Returns error or nil no errors occured.

func (*KafkaMessageQueue) Peek 

func (c *KafkaMessageQueue) Peek(correlationId string) (*cqueues.MessageEnvelope, error)

Peek method are peeks a single incoming message from the queue without removing it. If there are no messages available in the queue it returns nil. Parameters:

  • correlationId string (optional) transaction id to trace execution through call chain.

Returns: result *cqueues.MessageEnvelope, err error message or error.

func (*KafkaMessageQueue) PeekBatch 

func (c *KafkaMessageQueue) PeekBatch(correlationId string, messageCount int64) ([]*cqueues.MessageEnvelope, error)

PeekBatch method are peeks multiple incoming messages from the queue without removing them. If there are no messages available in the queue it returns an empty list. Important: This method is not supported by Kafka. Parameters:

  • correlationId (optional) transaction id to trace execution through call chain.
  • messageCount a maximum number of messages to peek.

Returns: callback function that receives a list with messages or error.

func (*KafkaMessageQueue) ReadMessageCount 

func (c *KafkaMessageQueue) ReadMessageCount() (int64, error)

ReadMessageCount method are reads the current number of messages in the queue to be delivered. Returns number of messages or error.

func (*KafkaMessageQueue) Receive 

func (c *KafkaMessageQueue) Receive(correlationId string, waitTimeout time.Duration) (*cqueues.MessageEnvelope, error)

Receive method are receives an incoming message and removes it from the queue. Parameters:

  • correlationId string (optional) transaction id to trace execution through call chain.
  • waitTimeout time.Duration a timeout in milliseconds to wait for a message to come.

Returns: result *cqueues.MessageEnvelope, err error receives a message or error.

func (*KafkaMessageQueue) RenewLock 

func (c *KafkaMessageQueue) RenewLock(message *cqueues.MessageEnvelope, lockTimeout time.Duration) (err error)

RenewLock method are renews a lock on a message that makes it invisible from other receivers in the queue. This method is usually used to extend the message processing time. Important: This method is not supported by Kafka. Parameters:

  • message *cqueues.MessageEnvelope a message to extend its lock.
  • lockTimeout time.Duration a locking timeout in milliseconds.

Returns: error receives an error or nil for success.

func (*KafkaMessageQueue) Send 

func (c *KafkaMessageQueue) Send(correlationId string, envelop *cqueues.MessageEnvelope) error

Send method are sends a message into the queue. Parameters:

  • correlationId string (optional) transaction id to trace execution through call chain.
  • envelope *cqueues.MessageEnvelope a message envelop to be sent.

Returns: error or nil for success.

func (*KafkaMessageQueue) SetReferences 

func (c *KafkaMessageQueue) SetReferences(references cref.IReferences)

Sets references to dependent components.

  • references references to locate the component dependencies.

func (*KafkaMessageQueue) Setup 

func (c *KafkaMessageQueue) Setup(kafka.ConsumerGroupSession) error

Setup is run at the beginning of a new session, before ConsumeClaim

func (*KafkaMessageQueue) UnsetReferences 

func (c *KafkaMessageQueue) UnsetReferences()

Unsets (clears) previously set references to dependent components.

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