fbp-manifest

Flow-Based Programming Manifest Tools

This repository provides a schema for Flow-Based Programming manifest (fbp.json) files, as well as tools for populating and validating them. The purpose of FBP manifest files is to provide a platform-agnostic registry of flow-based components available in a project.

Manifest files can be used by the FBP runtimes themselves for component loading, and is also useful for development tools like Flowhub or DrawFBP.

Status

Early stages

Tools

• fbp-manifest-list: Discover available components and list them
• fbp-manifest-deps: Produce a manifest consisting only of dependencies of a given component
• fbp-manifest-stats: Show component reuse statistics for a project
• fbp-manifest-validate: Validate a FBP manifest file against the schema

Runtime support

FBP Manifest has been designed to have a plugin architecture where the developers of different flow-based runtimes can add support for their system. See src/runtimes for how to do this. Runtimes can of course also just implement fbp.json generation and consumption on their own, and merely utilize the JSON schemas from this project to validate their structure.

Currently supported FBP runtimes are:

• NoFlo
• MsgFlo

Manifest structure

FBP manifests consist of the following information:

• version: version of the manifest specification, currently 1
• modules: array of module definitions
• main: (optional) main component definition for running the project

The modules are objects with the following:

• name: name of the module
• runtime: runtime the module is for, for example noflo-nodejs
• base: base directory path of the module, relative to project root
• components: array of components contained in the module
• description: (optional) human-readable description for the module
• icon: (optional) default icon for components of the module, following Font Awesome naming conventions

Modules supporting multiple runtimes can appear multiple times in a manifest, once per each supported runtime. For example a NoFlo module that has some common components, and specific components for Node.js and browsers may have three entries with specific runtimes: noflo, noflo-nodejs, and noflo-browser. A manifest can contain modules for an arbitrary number of different runtimes.

Components are objects with the following:

• name: name of the component
• path: path used for executing the component. For example a Node.js require path or Java class path
• exec: command used for starting an instance of the component for components that are standalone processes
• elementary: boolean on whether the component is elementary (code) or not (graph)
• source: (optional) path to the source code of the component
• inports: (optional) array of inport definitions for the component
• outports: (optional) array of outport definitions for the component

Each component needs to provide at minimum the information the runtime needs to run it. Additionally it can provide metadata usable for flow-based programming tools like a ports listing. Either path or exec needs to be provided.

The full manifest structure can be found in the schema. Manifest files can be validated against the JSON schema or with the fbp-manifest-validate tool.

Extending

It is possible to extend the manifest files with custom runtime-specific information. To do this, place the custom values under a key named after the runtime they're for. So, for example NoFlo's custom information about a component would go under a noflo key:

{
  "name": "Merge",
  "path": "components/Merge.js",
  "source": "components/Merge.coffee",
  "elementary": true,
  "noflo": {
    "async": false
  }
}

Background

• FBP Protocol: component
• NoFlo issue 247: FBP project manifest
• FBP Glossary