wfx

A lightweight, general-purpose workflow executor.

Overview

Workflows are modeled as finite-state machines and are instantiated as Jobs through which the wfx and a client progress in lock-step to perform a task. Such a task could be software updating the client, progressing a work item through Kanban, … in essence anything requiring cooperation and coordination.

As being general purpose, wfx is only concerned with driving the (state) machinery, the specific actions a client should perform are encoded in the client implementation(s). Hence, one wfx instance can drive a multitude of wholly different workflows. Instantiating a workflow as a job augments it with additional metadata, the Job Definition, which contains job-specific information such as, e.g., URLs or other data the client (implementation) can make use of for this particular job.

To illustrate the concepts as well as the wfx / client interaction, consider the following figure

┌──────────────────────────────────────┐                       ┌──────────────┐
│                 wfx                  │                     ┌─┴────────────┐ │
│                                      │                     │   Client Y   │ │
│                                      │     poll for jobs   │              │ │
│                instantiate ┌───────┐ │◀────────────────────│              │ │
│  ┌────────────┐        ┌──▶│ Job 1 │ │────────────────────▶│──────┐       │ │
│  │ Workflow A ├────────┤   └───────┘ │◀─┐  job information │      ▼       │ │
│  └────────────┘        │   ┌───────┐ │  │                  │     act      │ │
│                   ┌────┼──▶│ Job 2 │ │  └──────────────────│◀─────┘       │ │
│  ┌────────────┐   │    │   └───────┘ │     update state    │              │ │
│  │ Workflow B ├───┘    │   ┌───────┐ │                     │              │ │
│  └────────────┘        └──▶│ Job 3 │ │           .         │              │ │
│                            └───────┘ │           .         │              │ │
│       ...                     ...    │           .         │              │ │
│                                      │                     │              ├─┘
└──────────────────────────────────────┘                     └──────────────┘

with the wfx having loaded a number of workflows Workflow A, Workflow B, … that got instantiated as Job 1, Job 2, Job 3, … with a Client Y working on Job 1: It polls the wfx for a new job or the current job's status, in return receives the job information, performs actions if applicable, and finally reports the new job status back to the wfx. This lock-step procedure is repeated until the workflow reaches a terminal state which could be identified with, e.g., success or failure.

wfx in (Example) Action

An exemplary Kanban-inspired workflow illustrating the interplay between the wfx as Kanban "Board", a Product Owner creating jobs, and a Developer executing them:

wfx Features & Non-Features

• Design Guidelines
  • Compact, scalable core focusing on the essentials
  • Proper interfaces to external systems for modularity and integrability: Accompanying and necessary services like artifact storage and device registry are likely already available or are better provided by specialized solutions
• Implementation
  • Extendable modularized source code architecture
  • Lightweight, no dependencies (statically linked binaries)
  • Efficient, native code for a wide variety of platforms and operating systems (as supported by the Go Language)
  • Fully documented REST API, see wfx OpenAPI Specification
  • Extensive test suite including load tests
• Deployment / Usability
  • Load / Unload workflows at run-time
  • Hot / Live reload of configuration file
  • Persistent Storage: built-in support for SQLite, PostgreSQL and MySQL
  • A complimentary built-in file server serving as artifact storage for dynamic deployments and integration without external file storage
  • Transport Layer Security (HTTPS) with support for custom certificates

wfx Clients

Currently, the following clients have support for wfx:

• SWUpdate - Software Update for Embedded Linux Devices implementing support for the Device Artifact Update Workflow Family

Documentation

Grouped by topic, the following documentation is available in docs/:

• Workflows: Core concepts of Workflows and Jobs
• Installation: How to install and deploy wfx.
• Configuration: How to configure wfx.
• Operation: How to operate wfx.
• Use-Cases: A collection of use-cases for wfx.
• API: wfx's north- and southbound APIs.

You can also browse the rendered documentation at https://siemens.github.io/wfx/.

Roadmap

The roadmap is tracked via Github issues.

Contributing

Contributions are encouraged and welcome!

See CONTRIBUTING.md for details.

License

Copyright ©️ 2023 Siemens AG.

Released under the Apache-2.0 license.