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AmqpTrigger.node.ts
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AmqpTrigger.node.ts
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import type { ContainerOptions, EventContext, Message, ReceiverOptions } from 'rhea';
import { create_container } from 'rhea';
import type {
ITriggerFunctions,
IDataObject,
INodeType,
INodeTypeDescription,
ITriggerResponse,
IDeferredPromise,
IRun,
} from 'n8n-workflow';
import { deepCopy, jsonParse, NodeOperationError } from 'n8n-workflow';
export class AmqpTrigger implements INodeType {
description: INodeTypeDescription = {
displayName: 'AMQP Trigger',
name: 'amqpTrigger',
// eslint-disable-next-line n8n-nodes-base/node-class-description-icon-not-svg
icon: 'file:amqp.png',
group: ['trigger'],
version: 1,
description: 'Listens to AMQP 1.0 Messages',
defaults: {
name: 'AMQP Trigger',
},
inputs: [],
outputs: ['main'],
credentials: [
{
name: 'amqp',
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: 'e.g. n8n',
description: 'Leave empty for non-durable topic subscriptions or queues',
hint: 'for durable/persistent topic subscriptions',
},
{
displayName: 'Subscription',
name: 'subscription',
type: 'string',
default: '',
placeholder: 'e.g. order-worker',
description: 'Leave empty for non-durable topic subscriptions or queues',
hint: 'for durable/persistent topic subscriptions',
},
{
displayName: 'Options',
name: 'options',
type: 'collection',
placeholder: 'Add Option',
default: {},
options: [
{
displayName: 'Container ID',
name: 'containerId',
type: 'string',
default: '',
description: 'Will be used to pass to the RHEA Backend as container_id',
},
{
displayName: 'Convert Body To String',
name: 'jsonConvertByteArrayToString',
type: 'boolean',
default: false,
description:
'Whether to convert JSON Body content (["body"]["content"]) from Byte Array to string. Needed for Azure Service Bus.',
},
{
displayName: 'JSON Parse Body',
name: 'jsonParseBody',
type: 'boolean',
default: false,
description: 'Whether to parse the body to an object',
},
{
displayName: 'Messages per Cicle',
name: 'pullMessagesNumber',
type: 'number',
default: 100,
description: 'Number of messages to pull from the bus for every cicle',
},
{
displayName: 'Only Body',
name: 'onlyBody',
type: 'boolean',
default: false,
description: 'Whether to return only the body property',
},
{
displayName: 'Parallel Processing',
name: 'parallelProcessing',
type: 'boolean',
default: true,
description: 'Whether to process messages in parallel',
},
{
displayName: 'Reconnect',
name: 'reconnect',
type: 'boolean',
default: true,
description: 'Whether to automatically reconnect if disconnected',
},
{
displayName: 'Reconnect Limit',
name: 'reconnectLimit',
type: 'number',
default: 50,
description: 'Maximum number of reconnect attempts',
},
{
displayName: 'Sleep Time',
name: 'sleepTime',
type: 'number',
default: 10,
description: 'Milliseconds to sleep after every cicle',
},
],
},
],
};
async trigger(this: ITriggerFunctions): Promise<ITriggerResponse> {
const credentials = await this.getCredentials('amqp');
const sink = this.getNodeParameter('sink', '') as string;
const clientname = this.getNodeParameter('clientname', '') as string;
const subscription = this.getNodeParameter('subscription', '') as string;
const options = this.getNodeParameter('options', {}) as IDataObject;
const parallelProcessing = this.getNodeParameter('options.parallelProcessing', true) as boolean;
const pullMessagesNumber = (options.pullMessagesNumber as number) || 100;
const containerId = options.containerId as string;
const containerReconnect = (options.reconnect as boolean) || true;
const containerReconnectLimit = (options.reconnectLimit as number) || 50;
if (sink === '') {
throw new NodeOperationError(this.getNode(), 'Queue or Topic required!');
}
let durable = false;
if (subscription && clientname) {
durable = true;
}
const container = create_container();
let lastMsgId: string | number | Buffer | undefined = undefined;
container.on('receiver_open', (context: EventContext) => {
context.receiver?.add_credit(pullMessagesNumber);
});
container.on('message', async (context: EventContext) => {
// No message in the context
if (!context.message) {
return;
}
// ignore duplicate message check, don't think it's necessary, but it was in the rhea-lib example code
if (context.message.message_id && context.message.message_id === lastMsgId) {
return;
}
lastMsgId = context.message.message_id;
let data = context.message;
if (options.jsonConvertByteArrayToString === true && data.body.content !== undefined) {
// The buffer is not ready... Stringify and parse back to load it.
const cont = deepCopy(data.body.content);
data.body = String.fromCharCode.apply(null, cont.data as number[]);
}
if (options.jsonConvertByteArrayToString === true && data.body.content !== undefined) {
// The buffer is not ready... Stringify and parse back to load it.
const cont = deepCopy(data.body.content);
data.body = String.fromCharCode.apply(null, cont.data as number[]);
}
if (options.jsonConvertByteArrayToString === true && data.body.content !== undefined) {
// The buffer is not ready... Stringify and parse back to load it.
const content = deepCopy(data.body.content);
data.body = String.fromCharCode.apply(null, content.data as number[]);
}
if (options.jsonParseBody === true) {
data.body = jsonParse(data.body as string);
}
if (options.onlyBody === true) {
data = data.body;
}
let responsePromise: IDeferredPromise<IRun> | undefined = undefined;
if (!parallelProcessing) {
responsePromise = await this.helpers.createDeferredPromise();
}
if (responsePromise) {
this.emit([this.helpers.returnJsonArray([data as any])], undefined, responsePromise);
await responsePromise.promise();
} else {
this.emit([this.helpers.returnJsonArray([data as any])]);
}
if (!context.receiver?.has_credit()) {
setTimeout(
() => {
context.receiver?.add_credit(pullMessagesNumber);
},
(options.sleepTime as number) || 10,
);
}
});
/*
Values are documentet here: https://github.com/amqp/rhea#container
*/
const connectOptions: ContainerOptions = {
host: credentials.hostname,
hostname: credentials.hostname,
port: credentials.port,
reconnect: containerReconnect,
reconnect_limit: containerReconnectLimit,
username: credentials.username ? credentials.username : undefined,
password: credentials.password ? credentials.password : undefined,
transport: credentials.transportType ? credentials.transportType : undefined,
container_id: containerId ? containerId : undefined,
id: containerId ? containerId : undefined,
};
const connection = container.connect(connectOptions);
const clientOptions: ReceiverOptions = {
name: subscription ? subscription : undefined,
source: {
address: sink,
durable: durable ? 2 : undefined,
expiry_policy: durable ? 'never' : undefined,
},
credit_window: 0, // prefetch 1
};
connection.open_receiver(clientOptions);
// The "closeFunction" function gets called by n8n whenever
// the workflow gets deactivated and can so clean up.
async function closeFunction() {
container.removeAllListeners('receiver_open');
container.removeAllListeners('message');
connection.close();
}
// The "manualTriggerFunction" function gets called by n8n
// when a user is in the workflow editor and starts the
// workflow manually.
// 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
const manualTriggerFunction = async () => {
await new Promise((resolve, reject) => {
const timeoutHandler = setTimeout(() => {
container.removeAllListeners('receiver_open');
container.removeAllListeners('message');
connection.close();
reject(
new Error(
'Aborted, no message received within 30secs. This 30sec timeout is only set for "manually triggered execution". Active Workflows will listen indefinitely.',
),
);
}, 30000);
container.on('message', (context: EventContext) => {
// Check if the only property present in the message is body
// in which case we only emit the content of the body property
// otherwise we emit all properties and their content
const message = context.message as Message;
if (Object.keys(message)[0] === 'body' && Object.keys(message).length === 1) {
this.emit([this.helpers.returnJsonArray([message.body])]);
} else {
this.emit([this.helpers.returnJsonArray([message as any])]);
}
clearTimeout(timeoutHandler);
resolve(true);
});
});
};
return {
closeFunction,
manualTriggerFunction,
};
}
}