Learn how to build a sophisticated and user-configurable Slack Bot which gives customized trade reports to financial analysts using Serverless technologies on Azure. Learn the patterns we used and the architectural decisions we made from an experienced Serverless Enterprise developer and author.

1. Daniel Bass
Serverless Slack
Bots with Azure
Durable Functions

2. Daniel Bass
Senior Developer in Private Credit at M&G plc
https://amzn.to/2O1mJePhttps://amzn.to/2vovaKW https://www.danielbass.dev

3. The Problem

4. Trade Awareness
Fund Manager places order
for assets, which then get
bought or sold
Analyst that covers assets
may be unaware
Fund Managers team and
support team may be
unaware

5. My Customer
• Analyst working for one of our Private Credit teams
• Constructed manual report every morning

6. Solution

7. Durable Functions
Define Workflows
using real code
Execution is reliably
saved and can last for
hours, months or
indefinitely
Operation is entirely
Serverless
Hand off calculations
and data retrieval to
Azure Functions

8. Durable Orchestration
Get Configs Send to Slack
Get Trades Filter Trades

9. Durable Orchestrator

10. Notification Configuration Screen
Storage Account
CRUD Azure Functions
Azure Active Directory
Table Storage
React App

11. Notification Configuration Screen

12. Notification Configuration Screen

13. Why this architecture?
Secure Scalable
Rapid Development Scale to Zero

14. The Result

15. Automated Regular Notifications
Fund Manager places order
for assets, which then get
bought or sold
Analyst receives a
notification the next
morning for any assets they
cover
Fund Managers team and
support team receives
notification an hour later

16. Customer
• No longer needs to construct his manual report
• Can tweak and configure however much he wants
• Total reliability and earlier execution

17. Problems

18. Problem
Users began to report slow loading times
• Application Insights indicated these incidents were approximately 12 seconds in length
• They didn’t occur over 20 minutes after the hourly notification went off
• They were always accompanied by ‘startup’ traces that Durable Functions always does
when it starts and checks the state of all outstanding orchestrators

19. Problem

20. Problem
Enormous node_modules folder – 60mb!

21. Solution
Rewrite code to remove
need for dependencies
Introduce build tool that ‘Tree-
shakes’ dependencies
Add Keep Alive function to
Function App

22. Future Extensions

23. Workflow Management
Slack Interactive Messages with Bolt Durable Functions Workflows

24. Bolt on Azure Functions
• Slack model is event-based – when a user interacts with your bot they issue a message
describing that event to your registered publically available url
• Slack have produced a convenient developer framework that uses Express on Node.js
called Bolt which will set up everything required to receive these events and validate
they are actually from Slack
• This previously did not place nice with Azure Functions, as the runtime handles
requests, not a framework like express
• There are other issues, like Slack requiring a response within 3 seconds, which
terminates an Azure Functions execution

25. Bolt on Azure Functions
• I have released an open source npm library called ‘bolt-azure-functions-receiver' which
implements the logic you need to replace the built in Express method and use Bolt
• You can then kick off a Durable Functions orchestrator and respond within 3 seconds
easily

26. Durable Orchestrator
Azure Function
invokes library
and starts Bolt
framework to
help with
handling the
request
Orchestrator
continues as
background
process and
completes
action
Slack User
clicks on your
message and
Slack sends
you an event
to HTTP
triggered
function
Starts
Orchestrator
and returns
200 OK

27. We’re Hiring:
global.mandg.com/careers