Blog

Getting POST requests to work with Axios, Kemal (crystal lang), vue.js

In picockpit.com, I am using AJAX requests to communicate with the backend for update operations. For instance,if you want to change the name of this Pi, you would select:which shows an inline form:how to show this inline form with vue.js is besides the point of this post (even though very interesting!)Clicking on Cancel will cancel [...]

By | August 6th, 2019|Crystal Language, Vue.js|Kommentare deaktiviert für Getting POST requests to work with Axios, Kemal (crystal lang), vue.js

VerneMQ MQTT connection lost (8): AMQJS0008I Socket closed. different mountpoints

In my setup, I am rewriting the mountpoints of clients from the ones set up by the listeners to individual mountpoints depending on client group.The idea behind this is perfect isolation of multi-tenancy on the server. Individual clients from different groups thus are not able to see each other, even when subscribing to “#” (everything). [...]

By | Juli 28th, 2019|VerneMQ|Kommentare deaktiviert für VerneMQ MQTT connection lost (8): AMQJS0008I Socket closed. different mountpoints

Shopify & Langify modify checkout link

Shopify checkout is multilingualThe shopify checkout is multilingual:The trick is to have a &locale=en or &locale=en at the end of the link:You can therefore create buttons, etc. which take your user to the checkout, under the links ofhttps://buyzero.de/checkout?locale=dehttps://buyzero.de/checkout?locale=enwhich will set the locale to the appropriate language.(replace buyzero.de by your domain).Shopify LiquidLiquid is the Shopify template [...]

By | Juli 21st, 2019|Development|Kommentare deaktiviert für Shopify & Langify modify checkout link

Booting Alpine Linux on the Raspberry Pi Compute Module

In our project for a client we are using the Raspberry Pi Compute Module, along with a custom compute module carrier board (called the PCCB – Pi Control Carrier Board) which provides RS485, CAN, RS232, LAN, USB and a step-down for input voltages of 6 – 24 V. (If you are interested in customized hardware [...]

By | Juli 7th, 2019|Alpine Linux, Raspberry Pi Embedded Development|Kommentare deaktiviert für Booting Alpine Linux on the Raspberry Pi Compute Module

Debugging File upload / multipart upload and other HTTP requests

Sometimes you want to see the request as it is received by the server, without any handling / obscuring of the original request.For instance, to see whether different browsers handle file uploads differently. On the other hand, you do not want to write up your own mockup server, just to handle these requests, or install [...]

By | Juli 1st, 2019|Development|Kommentare deaktiviert für Debugging File upload / multipart upload and other HTTP requests

LetsTrust TPM SLB 9670VQ2.0 or SLB 9670XQ2.0?

A customer approached us about the difference between SLB 9670VQ2.0 and SLB 9670XQ2.0.VQ has a standard temperature range of (-20 .. +85°C), and XQ is the enhanced temperature range version (-40 .. + 85°C).As the Raspberry Pi itself has a standard temperature range, we use the VQ version on the LetsTrust TPM.

By | Juni 11th, 2019|Raspberry Pi Blog|Kommentare deaktiviert für LetsTrust TPM SLB 9670VQ2.0 or SLB 9670XQ2.0?

Changing the mountpoint on auth_on_register webhook for VerneMQ

It is possible to pass modifiers along with the “result”: “ok” return value of your webhook for VerneMQ.The official documentation of VerneMQ gives some examples for the syntax. changing the mountpointIt is also possible to change the mountpoint, however the client_id apparently has to be passed in as well!I have raised an issue with the [...]

By | Juni 9th, 2019|VerneMQ|Kommentare deaktiviert für Changing the mountpoint on auth_on_register webhook for VerneMQ

Maximimum length of credentials (username, password, clientid) in MQTT v3.1.1

The CONNECT packetThe MQTT CONNECT Control packet always contains a payload. It is the first packet, which the client must send to the server after the connection is established.It can only be sent once by the client, if a second CONNECT packet is sent, the server (broker) must process it as a protocol violation and [...]

By | Juni 9th, 2019|MQTT, VerneMQ|Kommentare deaktiviert für Maximimum length of credentials (username, password, clientid) in MQTT v3.1.1

Debugging VerneMQ connection / authentication problems for dual authentication with webhooks and vmq_diversity

TL;DRhttps://github.com/vernemq/vernemq/blob/master/apps/vmq_diversity/src/vmq_diversity_plugin.erlincludes a statement which will block authentication / authorization through any other channels if your Lua script returns “false”:will lead to:instead of trying other plugins, as you might have assumed!In order to avoid this problem, simply do not return anything from your Lua script, if you do not want to handle the message!DebuggingVerneMQ has a [...]

By | Juni 4th, 2019|VerneMQ|Kommentare deaktiviert für Debugging VerneMQ connection / authentication problems for dual authentication with webhooks and vmq_diversity

MQTT Topic Tree Design best practices, tips & examples

Generic MQTT BackgroundWith MQTT the sender and receiver are not aware of each other - the broker handles the messaging. This allows the messages to be separated in space, time, and intensity. The sender can send at the speed it wants, and the time it wants. The receiver can pick up the messages at the [...]

By | Mai 29th, 2019|Development, VerneMQ|Kommentare deaktiviert für MQTT Topic Tree Design best practices, tips & examples