RabbitMQ是否在有消息的情况下为使用者调用回调函数? [英] Does RabbitMQ call the callback function for a consumer when it has some message for it?

问题描述

RabbitMQ 是否在有某些消息的情况下为使用者调用回调函数，或者消费者需要轮询RabbitMQ客户端吗?

因此，在使用者方面，如果有PHP脚本，RabbitMQ可以调用它并将消息/参数传递给它.例如如果评级是在分片1上提交的，并且aggregateRating表在分片2上，那么分片2的RabbitMQ使用者会触发脚本aggRating.php并传递在分片1中插入的​​参数吗?

解决方案

您想要的是basic.consume，它允许代理将消息推送到客户端.

也就是说，库的实现方式有所不同.他们中的大多数人都支持basic.consume，但是由于所使用框架的固有局限性，因此有些人没有(最引人注目的是许多其他客户端所基于的官方RabbitMQ C客户端).

如果您的PHP库不支持basic.consume，则要么必须使用轮询(错误)，要么可以使用功能更完善的客户端之一来驱动脚本.例如，您可以编写一个从代理使用的Python或Java程序(因此，代理推动交付给他们)，并且他们可以在收到新消息时调用脚本. 官方教程是对AMQP API的很好介绍，也是一个很好的起点. >

从大多数角度来看，这是有效的，但确实需要与代理建立稳定的连接.

如果不确定各个客户端的功能，或者需要更多指导，请 RabbitMQ讨论邮件列表是一个提出问题的好地方.开发人员着眼于回答在那里发布的任何查询.

Does RabbitMQ call the callback function for a consumer when it has some message for it, or does the consumer have to poll the RabbitMQ client?

So on the consumer side, if there is a PHP script, can RabbitMQ call it and pass the message/parameters to it. e.g. if rating is submitted on shard 1 and the aggregateRating table is on shard 2, then would RabbitMQ consumer on shard 2 trigger the script say aggRating.php and pass the parameters that were inserted in shard 1?

解决方案

What you want is basic.consume, which allows the broker to push messages to clients.

That said, the libraries are implemented differently. Most of them have support for basic.consume, but because of inherent limitations of the frameworks used, some don't (most notably the official RabbitMQ C client on which a lot of other clients are based).

If your PHP library does not support basic.consume, you either have to use polling (bad), or you could use one of the more complete clients to drive the script. For instance, you could write a Python or Java program that consumes from the broker (so, the broker pushes deliveries to them) and they could call the script whenever a new message is received. The official tutorials are a great introduction to the AMQP APIs and are a good place to start.

This is efficient from most points of view, but it does require a stable connection to the broker.

If in doubt about the capabilities of the various clients, or if you need more guidance, the RabbitMQ Discuss mailing list is a great place to ask questions. The developers make a point of answering any query posted there.

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