IO · Connecting to external systems
Learn how to send email notifications and exchange data with external systems over HTTP.
1. Overview
The Flows built so far have processed and stored data within NARA. In a production environment, a Flow may also need to notify a person when a machine stops or send parcel counts to an ERP system.
This chapter introduces two ways to connect a Flow to external systems. Part 1 sends email notifications, while Part 2 exchanges data over HTTP.
| Direction | What it's for | |
|---|---|---|
| Part 1 · Email | One-way, out | Telling a person something happened |
| Part 2 · HTTP | Two-way | Exchanging data with another system |
Email is a one-way notification. The Flow sends and moves on; nothing comes back. HTTP is a conversation: the Flow asks, the other system answers, and the answer comes back into the Flow to be used.
Pick the one that matches the job
If a human needs to know, send an email. If a program needs to know, or the Flow needs an answer back, use HTTP. Reaching for the wrong one is the usual cause of a Flow that either spams an inbox or waits for a reply that was never going to arrive.
2. Learning Objectives
By the end of this chapter, the learner will be able to:
- Tell a one-way notification apart from a two-way exchange, and pick the right one for the job
- Get an App Password from Google and configure Email Initialise and Email Send to send mail from a Flow
- Insert values from earlier Nodes into an email subject and body with Template Expressions
- Explain the Request–Response cycle and what Polling is for
- Set up a Postman Mock Server to test a Flow against before the real API exists
- Configure an HTTP Client, a Polling Trigger, and an HTTP Client Request to pull data onto the Dashboard
3. Prerequisites
- Completed the Operation and the Database Table topic
- Familiar with the Variable: Create and Variable: Modify Nodes
- A Google account for Part 1, and Postman installed for Part 2
4. What's in this chapter
Part 1 · Email
Set up the sender account with an App Password, then send notification mail out of a Flow.
Part 2 · HTTP Connection
Poll an external server on an interval and show what comes back on the Dashboard, testing against a Postman Mock Server.
Start here
Part 1 is the shorter of the two and needs nothing installed beyond a Google account. Begin at Part 1 · Email · Sending mail from a Flow.
Database Table · Storing data in a table
Create a table with DB Table Initialize, define its Columns, and write rows with DB Table Row Insert or Modify, with a workshop that stores what the user enters on the Dashboard.
Part 1 · Email · Sending mail from a Flow
Get an App Password from Google, then configure Email Initialise and Email Send to send notification mail out of a Flow.