IMessageQueue

Interface for asynchronous message queues.

Extends: IOpenable, IClosable

Description

The IMessageQueue interface is used for asynchronous message queues.

Important points

  • Not all queues may implement all the methods.
  • An ttempt to call a non-supported method will result in a NotImplemented exception.
  • To verify if a specific method is supported check MessagingCapabilities.

Instance methods

abandon

Returns a 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 sent to dead letter queue.

abandon(message: MessageEnvelope): Promise<void>

beginListen

Listens for incoming messages without blocking the current thread.
See also IMessageReceiver, listen

beginListen(correlationId: string, receiver: IMessageReceiver): void

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

complete

Permanently removes a message from the queue. This method is usually used to remove the message after successful processing.

complete(message: MessageEnvelope): Promise<void>

endListen

Ends listening for incoming messages. When this method is called, listen unblocks the thread and execution continues.

endListen(correlationId: string): void

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.

getCapabilities

Gets the queue capabilities

getCapabilities(): MessagingCapabilities

getName

Gets the queue name

getName(): string

  • returns: string - queue name.

listen

Listens for incoming messages and blocks the current thread until queue is closed.
See also IMessageReceiver, receive

listen(correlationId: string, receiver: IMessageReceiver): void

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • receiver: IMessageReceiver - receiver used to receive incoming messages.

moveToDeadLetter

Permanently removes a message from the queue and sends it to the dead letter queue.

moveToDeadLetter(message: MessagingCapabilities): Promise<void>

peek

Peeks a single incoming message from the queue without removing it. If there are no messages available in the queue, it returns null.

peek(correlationId: string): Promise<MessageEnvelope>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • returns: Promise<MessageEnvelope> - peeked message or null.

peekBatch

Peeks multiple incoming messages from the queue without removing them. If there are no messages available in the queue, it returns an empty list.

peekBatch(orrelation_id: string, message_count: number): Promise<MessageEnvelope[]>

  • orrelation_id: string - (optional) transaction id used to trace execution through the call chain.
  • message_count: number - maximum number of messages to peek.
  • returns: Promise<MessageEnvelope[]> - peeked list with messages.

readMessageCount

Reads the current number of messages in the queue to be delivered.

readMessageCount(): Promise<number>

  • returns: Promise<number>umber - number of messages.

receive

Receives an incoming message and removes it from the queue.

receive(correlationId: string, waitTimeout: number): Promise<MessageEnvelope>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • waitTimeout: number - timeout in milliseconds to wait for a message to come.
  • returns: MessageEnvelope - received message or null.

renewLock

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.

renewLock(message: MessageEnvelope, lockTimeout: number): Promise<void>

  • message: MessageEnvelope - message to extend its lock.
  • lockTimeout: number - locking timeout in milliseconds.

send

Sends a message into the queue.

send(correlationId: string, envelope: MessageEnvelope): Promise<void>

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • envelope: MessageEnvelope - message envelop to be sent.

sendAsObject

Sends an object into the queue. Before being sent, the object is converted into JSON string and wrapped in a MessageEnvelope.

sendAsObject(correlationId: string, messageType: string, value: any):

  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • messageType: string - message type
  • value: any - object value to be sent

See also