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>
- message: MessageEnvelope - message to return.
beginListen
Listens for incoming messages without blocking the current thread.
See also IMessageReceiver, listen
beginListen(context: IContext, receiver: IMessageReceiver): void
- context: IContext - (optional) a context to trace execution through a 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>
- message: MessageEnvelope - message to remove.
endListen
Ends listening for incoming messages. When this method is called, listen unblocks the thread and execution continues.
endListen(context: IContext): void
- context: IContext - (optional) a context to trace execution through a call chain.
getCapabilities
Gets the queue capabilities
getCapabilities(): MessagingCapabilities
- returns: MessagingCapabilities - queue’s capabilities object.
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(context: IContext, receiver: IMessageReceiver): void
- context: IContext - (optional) a context to trace execution through a 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>
- message: MessageEnvelope - message to be removed.
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(context: IContext): Promise<MessageEnvelope>
- context: IContext - (optional) a context to trace execution through a 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(context: IContext, messageCount: number): Promise<MessageEnvelope[]>
- context: IContext - (optional) a context to trace execution through a call chain.
- messageCount: 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> - number of messages.
receive
Receives an incoming message and removes it from the queue.
receive(context: IContext, waitTimeout: number): Promise<MessageEnvelope>
- context: IContext - (optional) a context to trace execution through a 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(context: IContext, envelope: MessageEnvelope): Promise<void>
- context: IContext - (optional) a context to trace execution through a 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(context: IContext, messageType: string, value: any)
- context: IContext - (optional) a context to trace execution through a call chain.
- messageType: string - message type
- value: any - object value to be sent