sqs-json

Simplifies reception, processing, and removal of JSON objects stored in SQS.

npm install sqs-json

API

sqsJson.processJsonMessages(sqs, params, callback<message>) -> Promise

1. Polls a queue using provided sqs and params: sqs.receiveMessage(params)
2. Attempts to parse each message as JSON
3. If the message is a valid JSON, calls the provided callback
4. If the callback resolves for the given message, removes the message from the queue, otherwise leaves the message in the queue
5. Outputs the total number of messages, number of succeeded (resolved by callback), failed (rejected by callback OR invalid JSON messages), and an array of results for each message in the format defined below

Note: unless Raw Message Delivery is enabled for the queue subscription, the parsed message will also include AWS wrappers. You may want to enable this in your AWS console to work with pure JSON objects easier.

Example:

const
  AWS = require('aws-sdk'),
  sqsJson = require('sqs-json'),
  sqs = new AWS.SQS({ apiVersion: '2012-11-05' });

...

return sqsJson.processJsonMessages(sqs, {
  QueueUrl: 'https://sqs.us-east-1.amazonaws.com/12345678912/my-awesome-queue',
  MaxNumberOfMessages: 10,
  VisibilityTimeout: 30
}, (message) => {
  if (iWantThisMessage(message)) {
    return Promise.resolve({
      mySuccessfulResult: 'myValue'
    })
  } else {
    return Promise.reject('no!')
  }
});

Example response:

{
  "total": 3,
  "succeeded": 2,
  "failed": 1,
  "results": [
    {
      "isError": false,
      "result": {
        "mySuccessfulResult": "myValue"
      }
    },
    {
      "isError": true,
      "result": "no"
    },
    {
      "isError": true,
      "result": {
        "name": "MessageValidationError",
        "details": {
          "error": "SyntaxError: Unexpected token N in JSON at position 0",
          "rawMessage": {
            "MessageId": "900efefe-0342-4573-8920-fb24c3a8ce19",
            "ReceiptHandle": "AQEBA5...",
            "MD5OfBody": "8677b7d6bed5e6948ab6e232889940d5",
            "Body": "NotAJson"
          }
        }
      }
    }
  ]
}

In the example, the message corresponding to the first result will be removed from the queue as it was successful, while the remaining two will be rejected and stay in the queue adhering to SQS "maximum receives" policies.