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  /*
     This proposal builds on top of what was shipped in Preview 4 of Event Hubs library
     and attempts to discard a separate notion of EPH by rolling that feature into the
     existing concept of a "consumer".

     This is mainly geared towards JS and can be tweaked for Python
     This needs serious naming re-considerations for the methods on the consumer :)
  */

  const client = new EventHubClient(connectionString, eventHubName);

ramya-rao-a

/* 
Key changes:
- A dedicated "client" for EPH, making this a EventHubConsumerClient that customers would first gravitate towards
    - start() & stop() would be top level methods
    - In .Net, there would be 4 settable callbacks. These would be in the builder for Java.
    - For Python & JS, these would be passable to the start() method
    - State management is done via the PartitionContext that gets passed to the callbacks.
    - .Net & Java will have to allow users to extend the base class to store the state
- This results in a dedicated client for send for symmetry, and so EventHubProducerClient
    - send() & createBatch() would be top level methods, no need to create producers and maintain them

ramya-rao-a

// User class extending the base class provided by the library
class SamplePartitionProcessor extends PartitionProcessor {
    async processEvents(events) { console.log(events);}
    async processError(error) { console.log(error); }
    async initialize() { console.log(`Started processing partition: ${this.partitionId}`); }
    async close(reason) { console.log(`Stopped processing partition: ${this.partitionId} for reason ${reason}`); }
}

// 3 constructor overloads similar to EventHubClient, extra arguments are consumerGroupName, and PartitionProcessor
// Options are not shown, but are similar to what EventHubClientOptions support + max batch size, max wait time per batch

ramya-rao-a

/*
There are 3 players in this game.
- EventProcessor
   - Provided by the sdk.
   - Ideal Usage: Multiple instances on separate machines to balance partition load
- PartitionProcessor
   - Abstract class provided by the sdk, meant to be extended by user where they provide code to process events
   - Ideal Usage: 
      - Extended by user & passed to EventProcessor constructor via a factory in .Net & Java, 
         via the type/class name in JS & Python

ramya-rao-a

Proposed API design for EPH in Typescript

// Name to be changed
export class EventProcessor {
  constructor(
    consumerGroupName: string,
    eventHubClient: EventHubClient,

ramya-rao-a

// Main EventHubClient class
export class EventHubClient {
    // Expects connectionString with EntityPath set to event hub name
    constructor(connectionString: string, options?: EventHubClientOptions);

    // Expects user implemented token provider. Token is used for auth over cbs link
    constructor(host: string, entityPath: string, tokenProvider: TokenProvider, options?: EventHubClientOptions);

    // Expects user to use @azure/ms-rest-nodeauth library to create the credentials

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package main

import (
	"context"
	"fmt"
	"time"

	servicebus "github.com/Azure/azure-service-bus-go"
)

ramya-rao-a

/*
Set up instructions:
- Ensure you have Nodejs installed, else install from https://nodejs.org/en/
- Copy the this file to an empty folder
- Run `npm install @azure/service-bus` in this empty folder
- Add your connection string and partitioned queue (no sessions) details in the sample (use empty queue)
- Run `node deferred_receiveAndDelete_mode.js` (if you have named the file differently, use that name)
- Change the queue to other variations (unparitioned, sessions etc) and see the difference
*/

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/*
Set up instructions:
- Ensure you have Go installed, else install from https://golang.org/dl/
- Create a new folder and copy this file
- In that folder run `go mod init sbtests`
- Add your connection string and queue (no sessions) details
- Run `go run deferred_receiveAndDelete_mode.go` (if you have named the file differently, use that name)
*/

package main