RabbitSamples - A RabbitMQ Playground

Exchange

• Exchanges are the message router of RabbitMQ.
• Producers send message to exchanges.
• Queues are bound to one or more exchanges with a binding
• Exchanges receive messages from producers and route them to zero or more queues, depending to the binding.
• There are four exchange types;

1. Fanout
2. Direct
3. Topic
4. Headers

Fanout

• It sends all the messages it receives to all the queues that are bound to it.

Direct

• Routes messages to the queues based on the "routing key" specified in binding definition.

Topic

• Routes messages to the queues based on a pattern of the "routing key" specified in binding definition.
• Available wild cards are as follows:

* (asterisk): Matches exactly one word

“*.image” will match “convert.image”, but not “convert.bitmap.image” or “image.jpg”

# (hash): Matches zero or more words.

“image.#” will match “image.jpg” and “image.bitmap.32bit” but not “convert.image”

Header

• Routes messages to the queues based on the headers, ignoring the "routing key"
• “x-match” is the special header key whose value can be “all” or “any”. It determines the “match all” or “match any” logic for the matching process.

Scenario

Publish-Subscribe

• Publish-subscribe pattern is used to deliver the same message to one or more subscribers.
• There is one queue for each subscriber.
• Mostly used for event notifications.

Request-Response (RPC)

• Used when the publisher of the message (requestor) needs to get the response for its message.
• There are two queues: 1 for the requests, 1 for the responses
• Mostly used for command\queries