Process Engine

A simple helper for using multiple AWS SQS queues at the same time. This tool provides an easy way to map incoming events to actions.
Installation and Usage
npm install @cxcloud/process-engine
import {
  createQueueProcessor,
  createQueuePool
} from '@cxcloud/process-engine-core';
​
const pool = createQueuePool([
  createQueueProcessor(
    {
      name: 'my-sqs-queue',
      concurrency: 2
    },
    [
      {
        conditions: [
          {
            path: 'myEvent.name',
            value: 'someValue'
          },
          {
            path: 'customer.type',
            value: 'gold'
          }
        ],
        action: (message, sendMessage) => {
          console.log('Received Message:', message.data);
          message.deleteMessage().then(() => {
            // Next should be called after each message is processed
            message.next();
          });
        }
      }
    ],
    // CatchAll function (for events that don't match any of the processors)
    message => {
      console.error('No processor found');
      message.next();
    }
  ),
  createQueueProcessor(/* ... */),
  createQueueProcessor(/* ... */)
]);
​
pool.start();
Documentation
createQueuePool(processors: QueueProcessor[]) ⇒ QueuePool
This function creates a queue pool that can be started at the same time and queried to access each item.
The resulting QueuePool instance has the following methods:
start() — Start all the queue processor instances
findByName(name: String) ⇒ QueueProcessor — Find a queue processor instance
by it's name
createQueueProcessor(options, actionMap, fallbackFn) ⇒ QueueProcessor
options (Object)
name (String) — Required: name of the remote queue to be watched
region (String) — the region to send/read service requests. Default is
process.env.AWS_REGION
accessKeyId (String) — your AWS access key ID. Default is
process.env.AWS_ACCESS_KEY
secretAccessKey (String) — your AWS secret access key. Default is
process.env.AWS_SECRET_KEY
visibilityTimeout (Integer) — duration (in seconds) that the received
messages are hidden from subsequent retrieve requests after being retrieved
by a ReceiveMessage request.
waitTimeSeconds (Integer) — duration (in seconds) for which the call
will wait for a message to arrive in the queue before returning. If a
message is available, the call will return sooner than WaitTimeSeconds.
Default is 20
maxNumberOfMessages (Integer) — maximum number of messages to return.
Amazon SQS never returns more messages than this value but may return fewer.
Default is 1
concurrency (Integer) — number of concurrency fetcher to start. Default
is 1
debug (Boolean) — enable debug mode. Default is false
actionMap (Array of ActionMap). Each ActionMap (Object):
conditions (Array of Objects) — An array of conditions to meet. All of
the conditions must be met for the function to be triggered.
path (String) — Object path (of the received event body)
value (String) — Value of the object path
action (Function) — The action function to be called when the conditions are met for a received event. Params:
event (Object) — The received evemt
type (String): default is "Message"
data (Unknown): JSON.parsed message.Body or a string (if could not be
parsed)
message (Object): reference to the received message
name (String): name of the remote queue
url (String): url of the connected queue
deleteMessage() ⇒ Promise (Function):
Helper to deleteMessage (or SQS.deleteMessage()) when the job is completed.
changeMessageVisibility(timeout) ⇒ Promise (Function):
Helper to changeMessageVisibility (or SQS.changeMessageVisibility()) when the job is completed.
delay(timeout) ⇒ Promise (Function):
Helper to changeMessageVisibility (or SQS.changeMessageVisibility()) without completing the job.
sendMessage(params = {}) ⇒ Promise (Function): send a new message in the queue
next() (Function): call this method when you've completed your jobs
in the event callback.
sendMessage(params = {}) ⇒ Promise (Function) — A shortcut to send a message to the same queue processor that the event came from
fallbackFn — A fallback action in case a message doesn't match any conditions. Signature is same as the action mentioned above.
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Last modified 5yr ago