Persistent Compute Objects, or picos, are tools for modeling the Internet of Things. A pico represents an entity—something that has a unique identity and a long-lived existence. Picos can represent people, places, things, organizations, and even ideas.

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Picos use the event-query API to communicate with each other. So do applications using a programming style called the pico application architecture (formerly the personal cloud application architecture). The PAA is a variant on an architecture that is being promoted as unhosted web apps and remotestorage. PAA goes beyond those models by offering a richer API that includes not just storage, but other services that developers might need. In fact the set of services is infinitely variable in each pico.

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Wrangler

In the same way that operating systems provide more complex, more flexible services for developers than the bare metal of the machine, Wrangler provides pico programmers with important services that make picos easier to use and manage. For example, Wrangler provides services for creating new picos and creating communication channels between picos. (Wrangler was formerly known as CloudOS.)

Rulesets

The basic module for programming picos is a ruleset. A ruleset is a collection of rules that respond to events. But a ruleset is more than that. Functions in the ruleset make up the queries that are available in the event query API. Thus, the specific event-query API that a given pico presents to the world correlates exactly to the rulesets that are installed in the pico.

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I invite your questions and participation.

KRL

KRL Rulesets execute inside a persistent compute object, or pico. 

While rulesets are the primary organizing feature of KRL, you cannot program KRL without understanding picos. 

Event Binding

Persistent Data Variables

Rulesets

CloudOS

Operating systems provide significant benefits to personal computers:

• They made the microcomputer into a personal computer.
• They gave programmers incredible leverage through the services they provided.
• They made it so anyone can use a computer and get something done.

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Applications

PCAA

We have been using the model extensively for the last 6 months and have found it to be very effective for building CloudOS applications. I wrote about a largish experiment with this model in the whitepaper Introducing Forever: Personal Cloud Application Architectures. The white paper describes an application, called Forever, that uses picos to represent a social graph for purposes of creating an evergreen address book. The interface is built in an unhosted style using nothing but JavaScript. The picos provide the business logic and persistence layer. We called this the "personal cloud application architecture" or PCAA.

I wrote a simple Todo list application that used picos to store and manage todo list items do illustrate the simple calls that could be used to merely store and retrieve data from a pico's PDS in a simple PCAA. I describe that example in Building an App Using the Personal Cloud Application Architecture.

Developers building applications using the unhosted, PCAA style can sometimes get away without really thinking too much about the underlying model, but sophisticated applications will require a more detailed understanding. Developers programming picos to implement a particular system, of course, will need to be skilled at event-query systems in order to implement an effective and easy-to-use API. We're still developing our knowledge of how they work, how best to document them, and the best ways to promulgate our findings.