Netherite is a distributed workflow execution engine for Durable Functions (DF) and the Durable Task Framework (DTFx).

It is of potential interest to anyone developing applications on those platforms who has an appetite for performance, scalability, and reliability.

As Netherite is intended to be a drop-in backend replacement, it does not modify the application API. Existing DF and DTFx applications can switch to this backend with little effort.

To get started, you can either try out the sample, or take an existing DF app and switch it to the Netherite backend. You can also read our documentation.

The hello sample. For a quick start, take a look at hello sample. We included scripts that make it easy to build, run, and deploy this application. Also, this sample is a great starting point for creating your own projects.

Configure an existing DF app to use Netherite. If you have a .NET Durable Functions application already, and want to configure it to use Netherite as the backend, do the following:

• Add the NuGet package Microsoft.Azure.DurableTask.Netherite.AzureFunctions to your functions project.
• Create an EventHubs namespace. You can do this in the Azure portal, or using the Azure CLI.
• Configure EventHubsConnection with the connection string for the Event Hubs namespace. You can do this using an environment variable, or with a function app configuration settings.
• Optionally, update the host.json to tweak the settings for Netherite.

🎥 If you want to follow along migrating a Durable Function from Azure Storage to Netherite, we recommend the YouTube video Migrate your Durable Function to Netherite.

The default Azure Storage engine stores messages in Azure Storage queues and instance states in Azure Storage tables. It executes large numbers of small storage accesses. For example, executing a single orchestration with three activities may require a total of 4 dequeue operations, 3 enqueue operations, 4 table reads, and 4 table writes. Thus, the overall throughput quickly becomes limited by how many I/O operations Azure Storage allows per second.

To achieve better performance, Netherite represents queues and partition states differently, to improve batching:

• Partitions communicate via ordered, persistent event streams, over EventHubs.
• The state of a partition is stored using a combination of an immutable log and checkpoints, in Azure PageBlobs.

For some other considerations about how to choose the engine, see the documentation.

The current version of Netherite is 1.0.3. Netherite supports almost all of the DT and DF APIs. However, there are still some limitations:

• Supported hosted plans. Consumption plan is not supported yet, and auto-scaling only works on Elastic Premium plans with runtime-scaling enabled. This will be resolved by GA.
• Query Performance. Currently, query performance is suboptimal and does not support paging. We plan to add a range index implementation to fix this soon after GA.

To learn more about the Netherite architecture, you can also check out our paper on arXiv.

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repositories using our CLA.

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