TaskRouter events and batch processing framework

Written By: Jared Hunter

There are many long-running backend operations we want to be able to provide, but are currently hampered by the short runtime for Twilio serverless functions. Well, not any longer!

This repo introduces a protocol around batch processing that allows us create a array of work items that are then processed in batch, handing results from function to function in a daisy-chained manner.

The use case tackled to flush out this protocol was syncing worker objects with an array of their eligible queue SIDs - which could then be used, for example, on the Flex teams view to concretely see which workers are eligible for which queues.

Some points to note about this approach:

• The worker object has a max 4KB object size; 56 queue SIDs will take up about half this available space, so there is a limit to the success of this approach.
• Extensive testing with batch processing has shown it to work very reliably. I have been testing 5100 agents and the processing takes ~5 minutes, the error handling we have built into all of our functions has paid dividends here.
• In the future I imagine this approach being used for en masse updates of worker skills or anything else that will take a lot of operations.
• The batch processor passes back a Sync doc ID that can be used to monitor progress on the front end for future use cases.

Disclaimer

This software is to be considered "sample code", a Type B Deliverable, and is delivered "as-is" to the user. Twilio bears no responsibility to support the use or implementation of this software.

Pre-requisites

Make sure you have Node.js 18 as well as npm installed.

Next, please install the Twilio CLI. If you are using Homebrew on macOS, you can do so by running:

brew tap twilio/brew && brew install twilio

Finally, install the serverless plugin for the Twilio CLI:

twilio plugins:install @twilio-labs/plugin-serverless

Installation

First, clone the repository, change to its directory, and install:

git clone https://github.com/twilio-professional-services/tr-events-batch-processing.git

cd tr-events-batch-processing
npm install

Then, copy .env.example to .env and populate the following variables:

• TWILIO_FLEX_WORKSPACE_SID - assign the value of your Flex workspace
• TWILIO_FLEX_SYNC_SID - assign the value of the Sync service to use

Then, deploy the serverless functions:

twilio serverless:deploy

This will output a serverless domain for the deployed functions. We will use this in the next step.

Finally, we will set the deployed function to be used as the TaskRouter event callback:

1. Open Twilio Console > TaskRouter > Workspaces
2. Select the TaskRouter workspace, then choose Settings.
3. Set the "Event callback URL" to https://SERVERLESS_DOMAIN_FROM_ABOVE_GOES_HERE/event-handler
4. For "Callback events", select "Specific events"
5. Select the following events:
   • Task Queue Created
   • Task Queue Target Workers Expression Updated
   • Worker Created
   • Worker Attributes Updated
6. Click "Save"