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@nlpjs/fb-connector

Description

This module is a connector for @nlp.js to facilitate the creation of bots for Facebook Messenger.

Under the hood, it's leveraged the official module botbuilder-adapter-facebook.

Communication follows this process:

End user <- -> Fb page <- -> Fb backend <- -> Your backend

Installation

You can install @nlpjs/fb-connector:

    npm install @nlpjs/fb-connector

This module leverages some other @nlp.js dependencies:

@nlpjs/core
@nlpjs/connector
@nlpjs/bot
@nlpjs/express-api-server (optional, read "Server" section)

Cards

To be able to interact with user, aside of texts we can use Fb cards. As internal adapter communicates directly with Fb API we need to check documentation about cards into Facebook Developers site.

Setup

Environment variables required to work:

FACEBOOK_VERIFY_TOKEN=<***>
FACEBOOK_APP_SECRET=<***>
FACEBOOK_ACCESS_TOKEN=<***>
FACEBOOK_PAGE_ID=<***>

Server

As we need to expose a backend to receive information from Fb API, we can use express-api-server module for this. Every Facebook communication adds an step where signature of message is verified. This implies generating a SHA1 signature from raw body received.

As express.json body parser by default takes incoming rawBody field and replaces by a parsed body field, this forces us to add a little logic to intercept incoming buffer to be able to forward rawBody to that verify step. Have in mind that this doubles memory used per message.

This implies to override initialize step in ExpressApiApp:

class ExpressApiApp extends nlpjs.ExpressApiApp {

  initialize() {
    this.app = express();
    this.app.use(express.urlencoded({ extended: false }));
    
    this.app.use(express.json({
      verify: (req, res, buf) => {
        // INFO: rawBody is required for Facebook-connector
        req.rawBody = buf;
      }
    }));
    ...
  }

License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Usage no npm install needed!