Process Model Concepts

Process modeling is designing a process as a series of discrete, executable steps, and then analyzing and optimizing the design.

Process models, when built with the process library, are represented as a flowchart. Starting from an entry point, objects are sent through a process, acted upon and transformed by the process, and then at some point they reach an end node where they finish.

You can think of it like a flowchart - objects start at the source, travel through different blocks, and end at the sink.

A process model diagram

When designing your own process models, your primary task is to factor the real world process into discrete steps, and then match those steps to blocks in the process library (or build your own!)

Elements

With the HASH process library, we provide ready made behaviors for implementing process models. Each corresponds with a common element of process models.

  • Source: Generates objects based on a template.

  • Delay: Holds objects for a set number of timesteps.

  • Seize: Takes a resource and 'holds' it.

  • Release: Releases a resource that has been held by a seize block.

  • Service: A combination of Seize, Delay, And Release.

  • Select Output: Routes an object to a specific behavior depending on the state of the output or a conditional check.

  • Sink: Accepts objects and removes them from the process model.

The full list of process blocks and their parameters are listed in Process Blocks.

These blocks are published behaviors that you use in the behaviors array just like any others, and they execute in sequence. Objects are passed through the different blocks, representing a product on an assembly line, a bill being processed, etc. Each blocks in the behaviors array has a queue linked to it, where those objects are temporarily stored.

Additionally, you can add your custom blocks to perform custom logic. Create a new behavior, or fork the custom behavior, and add in your own code.

@hash/process/custom_process_template.js
// Forked custom_process_template.js to add a behavior
// that will increment a property on the object called count by 1.
/**
* @param {AgentState} state
* @param {AgentContext} context
*/
const behavior = (state, context) => {
// Get the queue of the next process block
let next_process_ind = state.behaviorIndex() + 1;
const behaviors = state.behaviors;
while (next_process_ind < behaviors.length) {
if (behaviors[next_process_ind].includes("@hash/process")
|| context.globals().process_behaviors.includes(behaviors[next_process_ind])) {
break;
} else {
next_process_ind += 1;
}
}
const next_process = state.process_labels[next_process_ind];
let queue = state[next_process + "_queue"];
// Run custom logic with the queue
for (obj of queue) {
obj.count ? obj.count += 1 : obj.count = 1
}
// Reassign to the process queue
state[next_process + "_queue"] = queue;
};