NoCMS MQ Api

Commit message format and publishing

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Fluent API for handling rabbit mq messaging in NoCMS.

Installation

npm install nocms-mq-api --save

Examples

Send a message

const mq = require('mq');

// Send a message of certain type
const msgObj = {
  data: { foo: 'Foo' }
};

mq.send('my-message', msgObj);

Subscription

mq.connect(config)
  .subscribe('my-message', (msg) => {
    console.log(msg.data.foo); // --> Foo
  });

Responding

This example has a handler responding to ping messages with the value pong and the other way around.

mq.connect(config)
  .subscribe('ping-message', (msg) => {
    const response = { value: msg.data.value === 'ping' ? 'ping' : 'pong' };
    mq.respond(msg, null, response)
  });

const pingMsg = {
  data: value: 'ping',
};

const responseHandler = (err, response) => {
  console.log(response.value); // --> pong
};

mq.send('ping-message', pingMsg, responseHandler);
mq.respond(msg, null, response)

The Message Object

{
  type: 'Name of message type',
  userToken: 'An optional token for identifying an end user',
  adminToken: 'An optional token identifying a NoCMS user',
  data: 'An object or value representing the message payload',
  originId: 'A generated read only guid for a message'
}

API

connect, (config)

Establish connection to and AMQP server. config = { host: Address to the server, login: mq user name, password: mq password, vhost: mq vhost, exchange: name of the exchange to connect to, queue: name of the queue to subscribe to }

send, (messageObj, [callback])

Publishes message of type messageName on the queue.

If callback is provided, this will be called if a response message is returned.

subscribe, (messageName, handlerFunction)

Subscribe to a message of a certain type. The handler function will be invoked with the message object as a single argument.

respond, (originalMessage, error, response)

The respond function takes the original message object and publishes a new message of type response-message referencing the original message by it's originId.

Events: on, (eventType, callback)

Add event handlers using the api.on function.

connection, (summary)

Triggers when connection to the exchange is established.

close, (summary)

Triggers when the connection to the mq is closed.

error, (err)

Triggers on transport errors and logical errors.

message, (msg)

Triggers every time a message is sent to the queue.