@corva/node-sdk

Corva node-sdk is a framework for building Corva DevCenter apps.

Contents

• Requirements;
• Quick start;
  • Install;
  • Create an app;
• App types;
  • Followable apps
• Writing a handler;
  • Example;
  • Event;
  • Context.

Requirements

• NodeJs 14 or later.

Quick start

Install

With npm (bundled with NodeJs, see docs):

$ npm i @corva/node-sdk

With yarn (docs):

$ yarn add @corva/node-sdk

With pnpm (docs):

$ pnpm add @corva/node-sdk

Create an app

A minimal app should export a handler that matches one defined in your manifest.json:

const { Corva } = require('@corva/node-sdk');

exports.handler = new Corva().task((event) => console.log(event));

For details on the app types, see App types.

App types

There are the following app types that you can build:

• Stream - works with real-time data;
• Scheduled - works with data at defined schedules/intervals (e.g., once a minute, once every three ft.);
• Task - works with data on-demand.

Followable apps

Stream & scheduled apps can be followed. Followable apps must produce data to trigger the chain reaction of apps' runs.

There are the following possible ways to make the app produce the data:

• Make a separate call to API specifying only indexes. See CorvaDataSource.produceMessages for details.
• Produce the data while saving. See Dataset.createEntriesAndProduceMessages for details

Writing a handler

To implement an app with node-sdk, you have to write a handler function that accepts two arguments:

• event - an event itself, see Events;
• context - helpers that are bound to app execution's context, see Context.

Handler example

const handler = (event, context) => {
    console.log(event, context);
}

Event

There are following types of events that match the related app types:

• Scheduled event - contains info about current invocation interval;
• Stream event - contains records that have been published since the last app invoke;
• Task - a task with which the app was invoked, which contains passed parameters.

Context

Context provides the next functionality:

• cache - convenient methods to work with the state; see State class. Not available for task apps;
• api - helper to interact with Corva API (and make any other generic request as well); see Api;
• logger - Logger instance; secrets - the application's sensitive data (see DevCenter docs, usage example, testing);
• config - some basic info about app invoke.