Weather station based on ESP32 and MicroPython

In one of the previous posts I briefly described sending data to Google Sheets from a ESP32 board using MicroPython. As I mentioned earlier, the code is available on GitHub. Here are the main features:

  1. Measuring temperature and humidity with DHT22 sensor.
  2. Sending data to a Google Sheet.
  3. Authentication via Google OAuth 2.0 service to get access to the sheet.
  4. Configuring the device via web browser.

The Google Sheet doesn’t need to be publicly available on the Internet. The device doesn’t require any middleman such as PushingBox or IFTTT.

In this post, let’s focus a bit on technical details.

ESP32 board and DHT22 sensor
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MicroPython on ESP32: sending data to Google Sheets

On a wonderful weekend in summer time, instead of going out to a beach or somewhere else, I was staying at home and wondering if it’s possible to send data from an ESP board to a Google sheet using my favorite MicroPython. Let’s say it can send temperature and humidity measured by a DHT22 sensor. That’s how the project started.

(this post contains a brief description of the project, more technical details can be found in the next post)

ESP32 development board and DHT22 sensor: sending data to a Google sheet.
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Transistor delay circuit

The transistor delay circuit may be helpful to learn some electronics basics. The circuit is pretty simple. It only contains a transistor, a capacitor, several resistors, a switch and an LED. The circuit uses an RC filter to turn an LED on with a little delay. Let’s see how we can choose elements for the circuit, and how the delay depends on parameters of the elements.

Transistor delay circuit on a breadboard
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Small hydroponic system at home

Increasing living space unavoidably results in filling up the new available space. In the end of last year I moved to a bigger apartment. Since I still have the same furniture, the unused space and volume keep bothering me. In the winter I built a shelving and now I store some useful stuff on it. In spring I got an idea to make a small garden at home. On weekend I built several wooden boxes, and put cherry tomatoes, onions and dill into it. But then I thought it’s not enough. I bought a couple of plastic containers and put more tomatoes. But I thought even that was not enough, and I got an idea to make a hydroponic system.

hydroponic system at home
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What’s new in Java 12

Let’s take a look what is inside Java 12. The new Java release contains less major enhancements than the previous version: 8 JEPs in Java 12 vs 17 JEPs in Java 11. As you of course remember, JEP stands for JDK Enhancement Proposal. Java 11 also had more closed entries in Jira: ~2700 in Java 11 vs ~2400 in Java 12. But it’s only mid of Feb 2019, maybe they can deliver 300 Jira entries by Mar 19th 2019 when Java 12 is planned to be released. Now let’s take a closed look what is in Java 12.

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Security testing for REST API with w3af

Nowadays more and more companies provide web APIs to access their services. They usually follow REST style. Such a RESTful web service looks like a regular web application. It accepts an HTTP request, does some magic, and then replies with an HTTP response. One of the main differences is that the reply doesn’t normally contain HTML to be rendered in a web browser. Instead, the reply usually contains data in a format (for example, JSON or XML) which is easier to process by another application.

Unfortunately, since a RESTful web service is still a web application, it may contain typical security vulnerabilities for web applications such as SQL injections, XXE, etc. One of the ways to identify security issues in web applications is to use web security scanners. Fortunately, since a RESTful web service is still a web application, we can use web security scanners to look for security issues in web APIs.

There are several well-known web security scanners. One of them is w3af created by Andres Riancho. I’ll focus on this scanner in the post.

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Tips about configuring security for REST API in Spring

In most cases, REST APIs should be accessed only by authorized parties. Spring framework provides many ways to configure authentication and authorization for an application. Another good thing is that the framework usually provides relatively good default settings. But nevertheless, it may be better to understand what’s going on rather then rely on the defaults.

This post contains a list of things which may be good to pay attention to when you configure or review authentication and authorization settings for a RESTful application based on Spring (boot) framework. However this is not a comprehensive guideline (if such a guideline even exist) which tells how to configure authentication and authorization for an application based on Spring framework. It’s more like a collection of tips and suggestions. Furthermore, any other suggestions and comments are more than welcome.

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What’s new security features in Java 11?

Java 11 was released on Sep 25th, 2018. This is the first long-term support release produced under the six-month cadence release model. Besides a huge number of small improvements and bug fixes, the new release contains 17 major enhancements including:

  • several updates in the Hotspot and garbage collectors
  • new HTTP client
  • Unicode 10
  • deprecating Nashorn JavaScript Engine and Pack200 tool
  • removing the Java EE and CORBA Modules
  • local-variable syntax for Lambda parameters
  • launch single-file source-code programs
  • and finally several security features

Although all these features are pretty cool, let’s focus on security in this post.

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