Simple Azure Function with Durable Entity

Content

This code repository contains a simple HTTP-triggered Azure function with a durable entity serving as a counter. This setup is propably the easiest way to get a first impression on Azure Durable Entitie on how they work.

Setup

Make sure that all requirements for local development of durable functions are fulfilled as described in the official documentation.

In addition I installed the extensions not via Extension Bundle but used the func install option i. e. func extensions install -p Microsoft.Azure.WebJobs.Extensions.DurableTask -v 2.2.0. (reason, see below)

How to Call

Start the function locally via npm run start
Use the REST client/CLI you like and trigger the following actions in the durable entity:
- a GET request at http://localhost:7071/api/HttpTrigger?name=<NameOfTheDurableEntity> to get the current value of durable entity <NameOfTheDurableEntity>
- a POST request at http://localhost:7071/api/HttpTrigger?name=<NameOfTheDurableEntity> to increase the value of durable entity <NameOfTheDurableEntity>. Here you have two options:
  - Using http://localhost:7071/api/HttpTrigger?name=<NameOfTheDurableEntity> will increase the value by one
  - Using http://localhost:7071/api/HttpTrigger?name=<NameOfTheDurableEntity>&increment=<incrementValue> will add thze value of the query parameter increment
- a DELETE request at http://localhost:7071/api/HttpTrigger?name=<NameOfTheDurableEntity> to reset the state of the durable entity <NameOfTheDurableEntity> to zero

By changing the <NameOfTheDurableEntity> you will se how things work, even after you stopped the function and restarted it.

Deviations from the official documentation (as of 23.12.2019)

The following mismatch with respect to the current official documentation exists :

The extensions are not installed via extension bundle as the extension entityTrigger is not recognized (which is consistent with the extension bundle JSON ), but via func install. This is current state of the art as described in the release notes of version 2.2.0
The binding of the EntityClient is an inbound binding as it would be for a OrchestrationClient. The documentation is not consistent here. It is ambivalent if you use in- or outbound binding, but I would stick to the status quo of the orchestration client

Updates

03/21/2020

Tested with Function runtime V3 (nodeJS 12 LTS) and Durable Extension 2.2.0
Added file RESTcalls.http. This way you can use the REST client of Visual Studio Code to issue the calls

lechnerc77 / AzureSimpleDurableEntity