@azure/core-lro

What is @azure/core-lro?

The @azure/core-lro package provides a framework for building and working with long-running operations (LROs) in Azure services. It offers a standardized way to poll for the status of these operations and retrieve the final results, abstracting the complexity involved in handling LROs.

What are @azure/core-lro's main functionalities?

Creating and managing long-running operations

This feature allows developers to implement custom pollers for managing long-running operations. The code sample demonstrates how to extend the Poller class to create a custom LRO poller.

const { Poller } = require('@azure/core-lro');

class MyLroPoller extends Poller {
  async cancelOperation() {
    // Cancel the operation if supported
  }

  async delay() {
    // Implement delay between polls
  }
}

const myPoller = new MyLroPoller();
await myPoller.pollUntilDone();

Polling for operation status

This feature enables polling for the status of a long-running operation until it is completed. The code sample shows how to use the Poller class to poll an operation until it's done.

const { Poller } = require('@azure/core-lro');

async function pollOperation(operation) {
  const poller = new Poller({
    operation,
  });

  return await poller.pollUntilDone();
}

Other packages similar to @azure/core-lro

async

The 'async' package provides utilities for working with asynchronous JavaScript, including control flow, iteration, and utilities functions. While it doesn't specifically target long-running operations, it offers tools that could be used to manage asynchronous tasks and operations, which could indirectly support LRO scenarios. However, it lacks the direct LRO management and polling capabilities of @azure/core-lro.

rxjs

RxJS is a library for reactive programming using Observables, to make it easier to compose asynchronous or callback-based code. This can be particularly useful for managing streams of events or asynchronous tasks, which could include long-running operations. However, RxJS does not provide specific abstractions for LROs like @azure/core-lro does, focusing instead on a broader set of reactive programming tools.

README

Azure Core LRO client library for JavaScript

This is the default implementation of long running operations in Azure SDK JavaScript client libraries which work in both the browser and NodeJS. This library is primarily intended to be used in code generated by AutoRest and autorest.typescript.

@azure/core-lro follows The Azure SDK Design Guidelines for Long Running Operations

Key links:

• Source code
• Package (npm)
• API Reference Documentation
• Samples

Getting started

Currently supported environments

• LTS versions of Node.js
• Latest versions of Safari, Chrome, Edge, and Firefox.

Installation

This package is primarily used in generated code and not meant to be consumed directly by end users.

Key concepts

SimplePollerLike

A poller is an object that can poll the long running operation on the server for its state until it reaches a terminal state. It provides the following methods:

• getOperationState: returns the state of the operation, typed as a type that extends OperationState
• getResult: returns the result of the operation when it completes and undefined otherwise
• isDone: returns whether the operation is in a terminal state
• isStopped: returns whether the polling stopped
• onProgress: registers callback functions to be called every time a polling response is received
• poll: sends a single polling request
• pollUntilDone: returns a promise that will resolve with the result of the operation
• stopPolling: stops polling;
• toString: serializes the state of the poller

OperationState

A type for the operation state. It contains a status field with the following possible values: notStarted, running, succeeded, failed, and canceled. It can be accessed as follows:

switch(poller.getOperationState().status) {
  case "succeeded":  // return poller.getResult();
  case "failed":     // throw poller.getOperationState().error;
  case "canceled":   // throw new Error("Operation was canceled");
  case "running":    // ...
  case "notStarted": // ...
}

createHttpPoller

A function that returns an object of type SimplePollerLike. This poller behaves as follows in the presence of errors:

• calls to poll and pollUntilDone will throw an error in case the operation has failed or canceled unless the resolveOnUnsuccessful option was set to true.
• poller.getOperationState().status will be set to true when either the operation fails or it returns an error response.

Examples

Examples can be found in the samples folder.

Troubleshooting

Logging

Logs can be added at the discretion of the library implementing the Long Running Operation poller. Packages inside of azure-sdk-for-js use @azure/logger.

Next steps

Please take a look at the samples directory for detailed examples on how to use this library.

Contributing

If you'd like to contribute to this library, please read the contributing guide to learn more about how to build and test the code.

Testing

To run our tests, first install the dependencies (with npm install or rush install), then run the unit tests with: npm run unit-test.

Code of Conduct

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [e-mail] with any additional questions or comments.