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Cloud Code Examples

This folder includes example cloud code that demonstrates how to add PL/SQL and Advanced Queueing as APIS for Mobile and Web Developers. This demo code is configured to run against Free23c. There is 1 new file

  1. qapi.js - a collection of cloud functions for supporting common queueing functions. These cloud fucntions are written using the Node.js Oracle module.

Configure the Server to use Cloud Code

Copy the cloud dir to the project root

cp -R src/Adapters/Storage/Oracle/cloud .

Add cloud code location to config.json

  "cloud": "./cloud/qapi.js",

And boot the server

ORACLE_CLIENT_LOCATION=/Users/myuser/instantclient_19_8  npm start -- ./config.json

New APIs

  1. Create Queue

    Input Parameter

    qname - name of queue

    curl -X POST -H "X-Parse-Application-Id: APPLICATION_ID" -H "Content-Type: application/json" -d '{ "qname": "FRED"}' http://localhost:1338/parse/functions/createQ

  2. Enqueue Message

    Input Parameter

    qname - name of queue to enqueu message

    msg - message to enque

    curl -X POST -H "X-Parse-Application-Id: APPLICATION_ID" -H "Content-Type: application/json" -d '{"qname": "FRED","msg": "Wilma says Hi"}' http://localhost:1338/parse/functions/enqueMsg

  3. Dequeue Message

    Input Parameter

    qname - name of queue to dequeue message

    curl -X POST -H "X-Parse-Application-Id: APPLICATION_ID" -H "Content-Type: application/json" -d '{"qname": "FRED"}' http://localhost:1338/parse/functions/dequeMsg

NOTE: The API will block if there are no messages to dequeue

Continuous Query Notification is used to get around this limitation. The message is then pushed to the mobile device using Parse Server's Push Notification suopprt. Look at the setCQN cloud code function which registers a callback.

There are a series of Linked In posts that describe this in detail

  1. Building a Custom MBaaS Server with Oracle's MERN Stack
  2. Using Oracle's Continuous Query Notifications in a Mobile App
  3. Push Notifications with Oracle's MERN Stack

Use the server connection pool

qapi.js embeds the credentials that are used to get an active conection. A better option would be to use the server's internal connection pool. Added to the cloud dir are;

connection.js - methods that get connections from the server pool qapisrvrpool.js - cloud code functions that now use connection.js to obtain connections from the server pool

To use the server pool, 3 modifications are required for OracleStorageAdapter.js

  1. import setter from connection.js

    import { setOracleStorageAdapter } from '../../../../cloud/connection';

    this assumes that cloud directory is subordinate to project root

  2. call setOracleStorageAdapter in connection.js during construction of Storage Adapter

    this._uri = options.databaseURI;
this._collectionPrefix = options.collectionPrefix;
this._connectionPool = null;
this._collections = new Map();
setOracleStorageAdapter(this);

  3. Enable events for connections in the pool. In the connect method add events: true

        this.connectionPromise = await oracledb.createPool({
      poolAlias: 'parse',
      user: user,
      password: pw,
      connectString: tnsname,
      poolIncrement: 5,
      poolMax: 100,
      poolMin: 3,
      poolTimeout: 10,
      enableStatistics: true,
      events: true,

Rebuild the server

npm cache clean --force
npm ci

Add cloud code location to config.json

  "cloud": "./cloud/qapisrvrpool.js",

And boot the server

ORACLE_CLIENT_LOCATION=/Users/myuser/instantclient_19_8  npm start -- ./config.json