[core] Introducing core-websockets

[deyaaeldeen]

Azure Core WebSockets Support

Overview

This pull request introduces the Azure Core WebSockets library for JavaScript. The package provides an isomorphic WebSocket client that seamlessly supports both Node.js and browser environments.

Key Contributions

• Isomorphic Client Support:

  • The library abstracts away environment-specific details by offering unified APIs that work across Node.js and browsers.
  • Supports sending and receiving data of standard datatypes across runtimes.

• Simplified Connection Management:

  • createWebSocketClient abstracts the complexity of connection establishment by handling URL validation, secure connection policies, and the retry and reconnection behavior to maintain connection reliability.

• Promise-Based & Event-Driven API:

  • Consumers can either await the WebSocket connection via Promise-like interface or register event callbacks (for events like open, message, close, and error). This dual approach makes it easier to integrate with a variety of application architectures.

• Backpressure Control:

  • Integrates a high water mark check in the send method to prevent overwhelming the send buffer.
  • If the buffered amount meets or exceeds the high water mark, a warning is logged and the send operation returns false, alerting the application to backpressure conditions.

• Logging:

  • Detailed logging is added for every state transition, including connection attempts, successful connections, disconnections, and errors.
  • Logging has been designed to suit long-running applications by eliminating redundant logs and maintaining compactness

[azure-sdk]

API change check

APIView has identified API level changes in this PR and created following API reviews.

@azure/core-websockets

[jeremymeng]

Nice to see this abstraction! I added some comments for discussion.

[xirzec]

Few minor comments, will need to take another look later.

[mpodwysocki]

Should we also think about a jitter here as well instead of just the base retry delays?