Managing your KRL code for rulesets

When using PicoStack, code and data are combined within a pico. Together they represent some entity, which is responsive and reactive.

The code is written in KRL, the language you will need to learn (after having learned enough HTML, CSS, and JavaScript to get started). Since KRL itself consists of ASCII text (except in character strings and comments (where you can insert other UNICODE characters)), you can use your favorite text editor or  integrated development environment (IDE) to write your code.

Besides maintaining this code on your own machine, you will probably want to use a code repository in the cloud. This post explores possibilities.

Web API needing a token grant

Web APIs that follow the OAuth pattern need special treatment.

Besides needing a client id and client secret, API calls that do actual work require a bearer token, which is generated by a special call to the API.

So, using such an API is a two step process:

1. Given the client id and secret, request a token
2. Supplying the token, make the API call that does actual work

While one could do the two steps for each actual API call, it is better practice to store the token from the first call in an entity variable and then use it in each API call that does actual work.

The end of programming?

While this blog has so far been mostly timeless, I'm going to comment here on a current event: an article arrived today in my mailbox, titled "The End of Programming"^* and subtitled, "The end of classical computer science is coming, and most of us are dinosaurs waiting for the meteor to hit," written by Matt Welsh.

I'm arguing that the use of PicoStack to develop small web applications could continue, long after most computer applications are developed using artificial intelligence (AI) techniques, and code is being written routinely by AI agents instead of humans.

Managing channels

A previous post, Pico channels, defines and describes channels, and prescribes some best practices for managing them. 

This post tells a story of bad consequences when that advice was ignored^*, and also describes a more resilient way to set up the channels for one particular application.

Consider a pico that records temperature readings from remote sensors. The sensors need a channel to post their readings periodically. A web application allowing the history of those readings to be explored also needs a channel to the pico.

Notifications

Each pico, from the moment it is created, is a first-class Internet resource, exposing a rich API of events and queries. It maintains a boundary between its internal state and the outside world.

When something interesting happens inside the pico the owner/controller of the pico may want to be notified.

A previous post about sending email illustrated this for that notification method. In this post, we'll discuss sending a message into a Microsoft Teams channel. Similar techniques can be used so that our pico can notify other message systems.

Scheduling events

Picos are a good fit for applications that have a relatively small amount of state for each entity, and that perform relatively quick computations, relatively infrequently.

Web applications fit that profile. From time to time, someone requests information about the state of an entity. That state is expressed as a web page, and that doesn't take a lot of time to compute.

Every so often, an event occurs that is of interest to the entity, and the pico reacts to that event by changing its state, which also doesn't require a lot of compute time.

Sometimes, though, we'll want the entity's pico to spontaneously wake up and do something. This is where scheduled events come into play.

Sending email via a web API

This is part four in a series^* on using web APIs to accomplish useful things in a PicoStack web application.

We have talked about consuming web APIs in a read-only fashion, safeguarding web API secrets when they are required, and wrapping the complexity of an API in a ruleset used as a module.

In this post, we'll use all of these techniques and demonstrate how to use a web API to send simple text email messages.