Show HN: A Web-to-RSS Parser in Common Lisp

A Web-to-RSS parser in Common Lisp.

This software was written because a disappointing number of websites still does not have an RSS or Atom feed so I could subscribe to their updates, e.g. the KiTTY website. The script tries to find new articles on any website according to given criteria (CSS selectors) and parse them into a valid RSS feed so I can subscribe to them in my usual RSS feed reader.

chmod +x rssparser.lisp, then:
./rssparser.lisp add []
./rssparser.lisp delete
./rssparser.lisp list
Run a simple web interface on port 5000:
./rssparser.lisp webserver
Cronjob or manual feed creation command:
Supported selectors are all valid CSS selectors. If you don’t specify a ContentSelector when adding a new feed, rssparser.lisp will use “Generated with rssparser.lisp.” as every feed item’s body.

If you want to subscribe to the KiTTY website, you can either use the web interface or perform the following commands:
% ./rssparser.lisp add “KiTTY” “” “.news” “h1” “”

% ./rssparser.lisp parse

% ./rssparser.lisp

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Original article

Switching from HTTP to MQTT with Help of AWS IoT

In the field of location tracking there needs to be lot of back-and-forth communication between devices and the backend. Device transmits location stream and health information (battery level, network strength, etc.). Backend processes this information, applies business logic on top and sends configuration commands back to devices in order to orchestrate tracking. These configuration commands determine when to start/stop tracking, frequency at which to collect GPS data (time and distance), frequency at which to transmit GPS data and so on.
In a world with patchy mobile networks making all this communication robust is quite a task. It is important to choose the right network protocol and design the communication semantics to get maximum benefit of the protocol’s capabilities. We recently switched a large part of our device-backend communication from HTTP to MQTT. This blog is about how we achieved it and our learning from it so far.

First of all, here’s why we

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