hiltvirginia.blogg.se - Message queue example

#Message queue example code#

A consumer processes a message (runs the process method of the.

The workflow of re-queuing messages (processor returns ``self::REQUEUE``) is the following: This will also happen if an exception is thrown during processing or job running. The message will be returned to the queue again and will be processed later. If a message cannot be processed temporarily, for example, in case of connection timeout due to server overload, the process method should return self::REQUEUE. This is abnormal behavior, the message should also be rejected, but the processor requires user attention (e.g., log a critical error or even throw an exception). For example, when an entity id was invalid or missing.

The message became unprocessable due to a failure.

As it is a typical workflow, user intervention is not required. The entity will not appear again, and we can reject the message. For example, when the message was sent to the entity that existed at the moment of sending but was at some point deleted.

The message became unprocessable as a result of routine work.

It means that the message was not processed and is removed from the queue because it is unprocessable and will never become processable (e.g., a required parameter is missing or another permanent error appears). Message Processor will return ``self::REJECT`` in the following cases: It means that the message was processed successfully and is removed from the queue. If a message was processed successfully.Message Processor will return ``self::ACK`` in the following cases: The received message can be processed, rejected, and re-queued. Also, if we split a process into a set of parallel processes, jobs allow monitoring and controlling of the whole set. Jobs are created in the DB and allow monitoring of the processes status, start and end time, and interrupt processes. Job - A message processor can process a message directly or create a job.One processor can subscribe to several topics. The topic name indicates which processor should be executed for the message. Message Topic - A class that contains a topic name (identifier), description, the default priority, and message body structure rules.

#Message queue example code#

Message Processor - Processes the queue messages (i.e., contains a code that should run when a consumer processes a message with the specified topic).

When implementing a message processor, a developer should remember that there can be several consumers working on different servers. It can be done to increase the performance.

There can be more than one consumer and they can work on different servers. For each message, the consumer runs a message processor subscribed to the message topic (if one exists). It processes one message at a time: once one message has finished being processed, the next message follows.

Consumer - A component that takes messages from the queue and processes them.

If there are several queues, it is much more difficult but more flexible sometimes. If we use only one queue, it is much easier.

Message Queue - A FIFO queue that holds queue messages until they are processed.Messages also contain a number of additional settings (see Message settings). When the message comes up to a consumer, its structure is validated, then passed to a message processor. Messages are validated and sent by a message producer and put to the “tail” of the message queue. Message - An information message which contains a message topic that indicates which message processor(s) will process it and a message body - an array of parameters required for the processing, for example, an entity id or a channel name.