Book Image

Practical Node-RED Programming

By : Taiji Hagino
5 (1)
Book Image

Practical Node-RED Programming

5 (1)
By: Taiji Hagino

Overview of this book

Node-RED is a free and open source flow-based programming tool used to handle IoT data that allows programmers of any level to interconnect physical I/O, cloud-based systems, databases, and APIs to build web applications without code. Practical Node-RED Programming is a comprehensive introduction for anyone looking to get up to speed with the Node-RED ecosystem in no time. Complete with hands-on tutorials, projects, and self-assessment questions, this easy-to-follow guide will help you to become well versed in the foundations of Node-RED. You’ll learn how to use Node-RED to handle IoT data and build web applications without having to write complex code. Once you’ve covered the basics, you’ll explore various visual programming techniques and find out how to make sample flows as you cover web development, IoT development, and cloud service connections, and finally build useful real-world applications. By the end of this book, you’ll have learned how to use Node-RED to develop a real-world application from scratch, which can then be implemented in your business.
Table of Contents (19 chapters)
Section 1: Node-RED Basics
Section 2: Mastering Node-RED
Section 3: Practical Matters

Learning about the input/output parameters of a node

Of the many nodes that Node-RED has, not many are suitable for calling web APIs (REST APIs). A typical node used when calling the web API is the http request node.

To call an external API on Node-RED, simply set the endpoint URL of the API to the URL property of the http request node.

For example, when it is necessary to set a parameter in the endpoint URL when calling an API, it is possible to set the output value of the previous node connected. The method is very easy. Instead of a literal string, you can just set the {{payload}} variable in the value setting part of the parameter.

In {{payload}}, the character string inherited from the previous processing node is entered.

Take the following example (note that this URL does not exist):{{payload}}&format=json:

Figure 7.2 – Setting the API endpoint URL with {{payload}} as a parameter

The process...