20 posts tagged with "tutorials"

The MQTT protocol is widely used in IoT applications because of its simplicity and ability to connect different data sources to applications using a publish/subscribe model. While many MQTT brokers support persistent sessions and can store message history as long as an MQTT client is not available, there may be cases where data needs to be stored for a longer period. In such cases, it is recommended to use a time series database. There are many options available, but if you need to store unstructured data such as images, sensor data, or Protobuf messages, consider using ReductStore. It is a time series database specifically designed for storing large amounts of blob data and optimized for IoT and edge computing.

ReductStore provides client SDKs for many programming languages to integrate it into your infrastructure. In this example, we will use the client SDK for JavaScript.

Let's make a simple application to understand how to keep a history of MQTT messages using ReductStore and Node.js.

This article provides an introduction to ReductStore and explains how to use the Reduct C++ SDK to subscribe to data from the database.

Prerequisites​

To subscribe to new records, we should use a continuous query, which has been supported by ReductStore since version v1.4. We can use the following Docker command to run it:

docker pull reduct/store:latest
docker run -p 8383:8383 reduct/store:latest

Now, we need to install the Reduct Client SDK for C++. Please refer to these instructions.

The ReductStore Project hosts the free "cats" dataset, which contains about 10K photos of cats in JPEG format with eye coordinates, a month, and ears as labels. In this example, we can learn how to download the dataset from the ReductStore instance and draw the features using the OpenCV library.

Installing Dependencies​

First, we need to install the ReductStore Client SDK for Python to download the photos and labels. We also need the OpenCV Python library for drawing features and Pillow to display images in the Jupyter environment:

pip install reduct-py opencv-python Pillow

Getting Data​

To retrieve data we need the URL of the ReductStore instance, the bucket name, where we store our datasets and an API token with read access, so that we can connect to the database by using the Client class:

from reduct import Client, Bucket

HOST = "https://play.reduct.store"
API_TOKEN = "reductstore"
BUCKET = "datasets"

client = Client(HOST, api_token=API_TOKEN)

bucket: Bucket = await client.get_bucket(BUCKET)