Apache Avro and .NET

Nov 15, 2018  

I am currently working on an implementation of an internal event bus, which will only accept typed messages. Having experimented lately with Apache Kafka I decided that I would use the Apache Avro serialization system.

Existing Apache Avro libraries for .NET

While looking into Avro, I came across a Microsoft implementation which is available under GitHub (see Microsoft.Hadoop.Avro), however the latest commit dates back to 2015 as of this writing.

Apache published .NET bindings for Apache Avro, yet not as a .NET Standard library.

Another active player in the market is Confluent. The company maintains its own fork under GitHub, but with the same limitation as the original Apache Avro C# library, making it incompatible with .NET Standard.

Forking and publishing Epsitec’s own Apache Avro library

I decided to fork the original apache/avro to epsitec-sa/avro and apply the minor changes required to build avro.main as a netstandard2.0 library.

  • Update the Solution file to Visual Studio 2017.
  • Create a Microsoft.NET.Sdk project file (Avro.main.std.csproj).
  • Remove unused reference to log4net and update package references.
  • Add the metadata needed to produce a NuGet package.

Creating a NuGet package

The reference material required to create a NuGet package is rich.

I referred to Create and Publish a Package using Visual Studio and Publishing a Package to build my first package and get it listed on nuget.org as Epsitec.Apache.Avro.

Publishing succeeded using this command line:

dotnet nuget push Epsitec.Apache.Avro. \
  -k ...API-key... \
  -s https://api.nuget.org/v3/index.json

While listening to Epsiode 122 of Frank and James’s MergeConflict podcast, I discovered SourceLink and decided to give it a try.

The NuGet package was therefore built and published using SourceLink and it should provide a greate source debugging experience for users who simply add the package Epsitec.Apache.Avro to their project.

Opening the Schema API

I needed to access the internal version of Avro.Schema.Parse(), as I needed to specify a list of already parsed types. The original Apache Avro library does not make this readly available to consumers. Now that I am working on a fork, I can add the missing APIs rather than having to play with reflection to reach internal methods. Yay!