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A sample API written in node.js implementing the Winding Tree booking interface
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README.md

WT Booking API

A sample implementation of the WT booking API specification in node.js.

This server is assumed to handle booking requests for a single hotel. Within this scope, it:

  • Validates booking requests against hotel data in WT (rate plans, cancellation policies, available rooms)

  • Checks the sender's trustworthiness and message integrity based on configurable trust clues and lists.

  • Performs the necessary bookkeeping directly in the WT platform (i.e. it updates availability data based on accepted booking requests). This implementation does not change availability for the date of departure.

Note: we do not expect this API implementation to be run in production "as is"; instead, we assume that it should serve more as an inspiration or as a basis on which actual integrations between existing systems and Winding Tree can be built.

Requirements

  • Nodejs 10.x

Development

In order to install and run tests, we must:

git clone git@github.com:windingtree/wt-write-api.git
nvm install
npm install
npm run resolve-swagger-references
npm test

Running in dev mode

To run the server, you need to go through the following steps:

  1. Make sure you have access to a running instance of wt-read-api and wt-write-api. Currently, version 0.8.x of wt-read-api is assumed.

  2. If you do not have one yet, create an account in the write API (see the README for instructions).

  3. If you have not done that yet, register your hotel in WT using the write API. Do not forget to upload the rate plans and initial availability data.

  4. Based on src/config/dev.js, prepare a new configuration file with the appropriate settings (read/write API urls, access keys, hotel ID, etc.). Let's assume you will store it as src/config/prod.js.

  5. Now you can run the server with the newly created configuration:

    WT_CONFIG=prod node src/index.js

Running this server

Docker

You can run the whole API in a docker container, and you can control which config will be used by passing an appropriate value to WT_CONFIG variable at runtime. Database will be setup during the container startup in the current setup. You can skip this with SKIP_DB_SETUP environment variable.

$ docker build -t windingtree/wt-booking-api .
$ docker run -p 8080:8935 -e WT_CONFIG=playground windingtree/wt-booking-api

After that you can access the wt-booking-api on local port 8080.

NPM

You can install and run this from NPM as well:

$ npm install -g @windingtree/wt-booking-api
$ WT_CONFIG=playground wt-booking-api

This will also create a local SQLite instance in the directory where you run the wt-booking-api command. To prevent that, you can suppress DB creation with SKIP_DB_SETUP environment variable.

Running in production

You can customize the behaviour of the instance by many environment variables which get applied if you run the API with WT_CONFIG=envvar. These are:

  • BASE_URL - Base URL of this API instance, for example https://booking-mazurka.windingtree.com.
  • DB_CLIENT - Knex database client name, for example sqlite3.
  • DB_CLIENT_OPTIONS - Knex database client options as JSON string, for example {"filename": "./envvar.sqlite"}.
  • READ_API_URL - URL of wt-read-api instance.
  • WRITE_API_URL - URL of wt-write-api instance.
  • SUPPLIER_ID - On-chain Address of the hotel or airline.
  • WRITE_API_KEY - Access Key for wt-write-api instance.
  • WALLET_PASSWORD - Password for an Ethereum wallet associated with used wt-write-api key.
  • LOG_LEVEL - Set log level for winston.
  • WT_SEGMENT - Choose segment (hotels, airlines) this instance is intended for. Defaults to hotels.
  • THROTTLING_ALLOW - Allows only 10 bookings and cancellation in one hour if allowed. Defaults to true.
  • ALLOW_UNSIGNED_BOOKING_REQUESTS - Accept only signed booking requests when false. Defaults to true.
  • SPAM_WHITELIST - Comma separated list of eth addresses to always allow. Defaults to empty list.
  • SPAM_BLACKLIST - Comma separated list of eth addresses to always reject. Defaults to empty list.

The following options are optional.

Checking

  • CHECK_AVAILABILITY - If false, no restrictions and no room quantity is checked. This may lead to overbooking. Defaults to true.
  • CHECK_CANCELLATION_FEES - If false, passed cancellation fees are not validated. This may lead to conditions unfavourable for a hotel. Defaults to true.
  • CHECK_TOTAL_PRICE - If false, the price is not validated against ratePlans. This may lead to conditions unfavourable for a hotel. Defaults to true.
  • DEFAULT_BOOKING_STATE - This state is assigned to every accepted booking. Can be confirmed or pending. Defaults to confirmed.

Data modification

  • UPDATE_AVAILABILITY - If false, availability is not updated in data stored in WT platform. This makes sense with using DEFAULT_BOOKING_STATE with pending value when you have to process the booking manually anyway. Defaults to true.
  • ALLOW_CANCELLATION - If false, booking cancellation is not allowed. Defaults to true.

Mailing

  • MAIL_SUPPLIER_CONFIRMATION_SEND - If true, a summary of each accepted booking is sent to MAIL_SUPPLIER_CONFIRMATION_ADDRESS. Requires configured mailer and that address. Defaults to false.
  • MAIL_CUSTOMER_CONFIRMATION_SEND - If true, a summary of each accepted booking is sent to the customer. Requires configured mailer. Defaults to false.
  • MAIL_SUPPLIER_CONFIRMATION_ADDRESS - E-mail address to which the hotel confirmations will be sent.
  • MAIL_PROVIDER - Denotes which mailing provider should be used. Supported values are dummy and sendgrid. Defaults to undefined.
  • MAIL_PROVIDER_OPTIONS - JSON string with options of any given mailing provider. For example {"from": "noreply@example.com"}. See providers implementation for particular options.

For boolean flags, any of '1', '0', 'true', 'false', 'yes', 'no' should work (case insensitive).

The CHECK_* options are good for testing or APIs that actually pass data to humans that are responsible for data validation. These should never be turned off in fully automated production-like environment as they may lead to unexpected and inconsistent results.

$ docker build -t windingtree/wt-booking-api .
$ docker run -p 8080:8935 \
  -e DB_CLIENT_OPTIONS='{"filename": "./envvar.sqlite"}' \
  -e DB_CLIENT=sqlite3 \
  -e WT_CONFIG=envvar \
  -e NODE_ENV=production \
  -e BASE_URL=https://booking.example.com \
  -e READ_API_URL=https://read-api.example.com \
  -e WRITE_API_URL=https://write-api.example.com \
  -e SUPPLIER_ID=0x123456 \
  -e WRITE_API_KEY=werdfs12 \
  -e WALLET_PASSWORD=windingtree windingtree/wt-booking-api

After that you can access the wt-booking-api on local port 8080. Database will also be setup during the container startup in the current setup. You can skip this with SKIP_DB_SETUP environment variable.

Examples

Book rooms

To perform a booking, you can send a request like this (just make sure that the specifics, such as hotel ID or room type IDs, are correct with respect to your hotel).

$ curl -X POST localhost:8935/booking -H 'Content-Type: application/json' --data '
{
  "hotelId": "0xe92a8f9a7264695f4aed8d1f397dbc687ba40299",
  "customer": {
    "name": "Sherlock",
    "surname": "Holmes",
    "address": {
      "line1": "221B Baker Street",
      "city": "London",
      "country": "GB"
    },
    "email": "sherlock.holmes@houndofthebaskervilles.net"
  },
  "pricing": {
    "currency": "GBP",
    "total": 221,
    "cancellationFees": [
      { "from": "2018-12-01", "to": "2019-01-01", "amount": 50 }
    ]
  },
  "booking": {
    "arrival": "2019-01-01",
    "departure": "2019-01-03",
    "rooms": [
      {
        "id": "single-room",
        "guestInfoIds": ["1"]
      },
      {
        "id": "single-room",
        "guestInfoIds": ["2"]
      }
    ],
    "guestInfo": [
      {
        "id": "1",
        "name": "Sherlock",
        "surname": "Holmes"
      },
      {
        "id": "2",
        "name": "John",
        "surname": "Watson"
      }
    ]
  }
}'

If everything went well, you should get a response with the status code "200" and you should see a change in the hotel's availability data.

There are more optional details you can send with the booking. You can check it in the API defintion.

The swagger definition for airlines is just a bit different:

$ curl -X POST localhost:8935/booking -H 'Content-Type: application/json' --data '
{
  "airlineId": "0xe92a8f9a7264695f4aed8d1f397dbc687ba40299",
  "customer": {
    "name": "Sherlock",
    "surname": "Holmes",
    "address": {
      "line1": "221B Baker Street",
      "city": "London",
      "country": "GB"
    },
    "email": "sherlock.holmes@houndofthebaskervilles.net"
  },
  "pricing": {
    "currency": "GBP",
    "total": 221,
    "cancellationFees": [
      { "from": "2018-12-01", "to": "2019-01-01", "amount": 50 }
    ]
  },
  "booking": {
    "flightNumber": "OK0965",
    "flightInstanceId": "IeKeix6G",
    "bookingClasses": [
      "bookingClassId": "business",
      "passengers": [
        "name": "John",
        "surname: "Watson",
      ],
    ],
  }
}'

Spam protection

Exposing booking API openly to the wild is vulnerable to spamming and other kinds of booking/cancellation requests by bad actors. We provide several methods which can be combined to prevent this.

Trust clues

An extensible list of trust clues allows you to evaluate virtually any desirable condition in order to determine whether to trust the sender or not. Please see documentation on the developer portal to learn more about trust clues.

Access lists

Beside trust clues - which may be complicated to set up and take time to evaluate (e.g. chain-based clues) - a simpler method of spam protection is provided in the form of SPAM_WHITELIST and SPAM_BLACKLIST envvars. All requests (both booking and cancellation) originated by addresses on blacklist will be rejected and whitelisted addresses will be accepted. For the rest the trust clues will be evaluated and request will be accepted if all clues evaluate to true. Request will be accepted if no trust clues are set up.

Lists can also be set via environment config files in /src/config.

Note that unless ALLOW_UNSIGNED_BOOKING_REQUESTS is set to false, caller may bypass blacklist by not sending its originAddress.

Message signing

To ensure the booking request has been sent by the declared party and not modified in transfer, it is recommended (and can be enforced by setting ALLOW_UNSIGNED_BOOKING_REQUESTS = false) to use signed requests.

A signed request contains an extra header (x-wt-signature) containing a signature generated using sender's private key. Signing can be done either using WtJsLibs.wallet.signData convenience method or directly with web3.eth_sign.

The API verifies the signature against the origin address and request data thus proving immutability and accountability of the request. It either directly compares the signer's address to the originAddress, or tries to check originAddress's associatedKeys for the presence of the recovered signer's address.

originAddress is an ETH address of the sender that serves as a public key, or an ORG.ID address. Signed data mean:

  • string representation of the body of a POST/PUT request (e.g. HotelBooking or AirlineBooking when creating a booking)
  • URI of a GET/DELETE request (e.g. https://booking.api/booking/1 when cancelling a booking)

POST and PUT methods

A raw string representation has to be used for both signing and verification as JSON serialization is ambiguous. You'll probably need to set the content-type header explicitly, depending on your HTTP request library.

GET and DELETE methods

As GET and DELETE HTTP methods should not contain request body, a different approach is used. The hash is computed from the URI. In this case the origin address is not part of the message and needs to be sent in a x-wt-origin-address header.

Upon verification the hash is also computed based on the URI (instead of the raw request body) and compared to the origin address from headers.

Creating a booking

const Web3Utils = require('web3-utils');
const wallet = wtJsLibs.createWallet(walletData);
wallet.unlock(walletPassword);

let booking = getBooking();  // HotelBooking or AirlineBooking according to docs/source.yaml
booking.originAddress = wallet.address;
let serializedData = JSON.stringify(booking);
let dataHash = Web3Utils.soliditySha3(serializedData);
let signature = await wallet.signData(dataHash);
request.post({
  uri: '/booking',
  body: serializedData,
  headers: {
    'x-wt-signature': signature,
    'content-type': 'application/json',
  }
});

Check hotel explorer code for a working example and src/services/signing/index.js for convenience methods.

Cancelling a booking

const Web3Utils = require('web3-utils');
const wallet = wtJsLibs.createWallet(walletData);
wallet.unlock(walletPassword);

let uri = `${bookingApi}/booking/${bookingId}`;
let dataHash = Web3Utils.soliditySha3(uri);
let signature = await wallet.signData(dataHash);
request.delete({
  uri: uri,
  headers: {
    'x-wt-signature': signature,
    'x-wt-origin-address': wallet.address,
  }
});

Further instructions on how to create a signed request are described in the developer's portal.

See our blog post for a detailed explanation.

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