n8n/packages/nodes-base/nodes/Amqp/AmqpTrigger.node.ts

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import { ContainerOptions } from 'rhea';
import { ITriggerFunctions } from 'n8n-core';
import {
INodeType,
INodeTypeDescription,
ITriggerResponse,
} from 'n8n-workflow';
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export class AmqpTrigger implements INodeType {
description: INodeTypeDescription = {
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displayName: 'AMQP Trigger',
name: 'amqpTrigger',
icon: 'file:amqp.png',
group: ['trigger'],
version: 1,
description: 'Listens to AMQP 1.0 Messages',
defaults: {
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name: 'AMQP Trigger',
color: '#00FF00',
},
inputs: [],
outputs: ['main'],
credentials: [{
name: 'amqp',
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required: true,
}],
properties: [
// Node properties which the user gets displayed and
// can change on the node.
{
displayName: 'Queue / Topic',
name: 'sink',
type: 'string',
default: '',
placeholder: 'topic://sourcename.something',
description: 'name of the queue of topic to listen to',
},
{
displayName: 'Clientname',
name: 'clientname',
type: 'string',
default: '',
placeholder: 'for durable/persistent topic subscriptions, example: "n8n"',
description: 'Leave empty for non-durable topic subscriptions or queues. ',
},
{
displayName: 'Subscription',
name: 'subscription',
type: 'string',
default: '',
placeholder: 'for durable/persistent topic subscriptions, example: "order-worker"',
description: 'Leave empty for non-durable topic subscriptions or queues',
},
]
};
async trigger(this: ITriggerFunctions): Promise<ITriggerResponse> {
const credentials = this.getCredentials('amqp');
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if (!credentials) {
throw new Error('Credentials are mandatory!');
}
const sink = this.getNodeParameter('sink', '') as string;
const clientname = this.getNodeParameter('clientname', '') as string;
const subscription = this.getNodeParameter('subscription', '') as string;
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if (sink === '') {
throw new Error('Queue or Topic required!');
}
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let durable = false;
if(subscription && clientname) {
durable = true;
}
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const container = require('rhea');
const connectOptions: ContainerOptions = {
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host: credentials.hostname,
port: credentials.port,
reconnect: true, // this id the default anyway
reconnect_limit: 50, // try for max 50 times, based on a back-off algorithm
container_id: (durable ? clientname : null)
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};
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if (credentials.username || credentials.password) {
container.options.username = credentials.username;
container.options.password = credentials.password;
}
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let lastMsgId: number | undefined = undefined;
const self = this;
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container.on('message', (context: any) => { // tslint:disable-line:no-any
if (context.message.message_id && context.message.message_id === lastMsgId) {
// ignore duplicate message check, don't think it's necessary, but it was in the rhea-lib example code
lastMsgId = context.message.message_id;
return;
}
self.emit([self.helpers.returnJsonArray([context.message])]);
});
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const connection = container.connect(connectOptions);
let clientOptions = undefined;
if (durable) {
clientOptions = {
name: subscription,
source: {
address: sink,
durable: 2,
expiry_policy: 'never'
},
credit_window: 1 // prefetch 1
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};
} else {
clientOptions = {
source: {
address: sink,
},
credit_window: 1 // prefetch 1
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};
}
connection.open_receiver(clientOptions);
// The "closeFunction" function gets called by n8n whenever
// the workflow gets deactivated and can so clean up.
async function closeFunction() {
connection.close();
}
// The "manualTriggerFunction" function gets called by n8n
// when a user is in the workflow editor and starts the
// workflow manually.
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// for AMQP it doesn't make much sense to wait here but
// for a new user who doesn't know how this works, it's better to wait and show a respective info message
async function manualTriggerFunction() {
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await new Promise(( resolve, reject ) => {
const timeoutHandler = setTimeout(() => {
reject(new Error('Aborted, no message received within 30secs. This 30sec timeout is only set for "manually triggered execution". Active Workflows will listen indefinitely.'));
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}, 30000);
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container.on('message', (context: any) => { // tslint:disable-line:no-any
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clearTimeout(timeoutHandler);
resolve(true);
});
});
}
return {
closeFunction,
manualTriggerFunction,
};
}
}