organization.md

Organization

The main components of pstack are shown and described below.

1. POETS Engines

Engines are arbitrary software/hardware components capable of simulating POETS devices as specified in the graph-schema spec and conforming to an additional (simple and minimal) protocol to govern their communication with Redis. pstack ships with a stand-alone POETS simulator psim that doubles as a compliant engine.

The engine specification is described in Developing pstack Engines.

2. POETS Daemon (pd)

This is a persistent background process that monitors the job queue on Redis and spawns engines to execute accepted jobs. It handles all aspects of job and process control (e.g. queueing, status reporting and logging).

3. POETS Client (pcli)

A super-charged Python terminal (syntax-coloring, auto-completion and persistent context) that serves as an entry point for users into a pstack service. It allows users to:

• Connect to a pstack deployment
• Start a process by loading a POETS XML file from their machines
• List and control running processes (through equivalent implementations of ps and kill)
• Monitor processes and back-end infrastructure in real time (through an equivalent implementation of top)
• Divide application devices into multiple subsets (called "regions") and map these to different engines