Available Relay APIs

Runtime APIs

The following table lists all currently available Relay runtime clients.

The additional information section contains more information about the status of each runtime library.

Language/Platform Available feature Client package Repository
.NET Standard Hybrid Connections Microsoft.Azure.Relay GitHub
.NET Framework WCF Relay WindowsAzure.ServiceBus N/A
Node Hybrid Connections WebSockets: hyco-ws
WebSockets: hyco-websocket
HTTP Requests: hyco-https

Additional information


The .NET ecosystem has multiple runtimes, hence there are multiple .NET libraries for the Relay. The .NET Standard library can be run using either .NET Core or the .NET Framework, while the .NET Framework library can only be run in a .NET Framework environment. For more information on .NET Frameworks, see framework versions.

The .NET Framework library only supports the WCF programming model and relies on a proprietary binary protocol based on the WCF net.tcp transport. This protocol and library is maintained for backwards compatibility with existing applications.

The .NET Standard library is based on the open protocol definition for the Hybrid Connections Relay that builds on HTTP and WebSockets. The library supports a stream abstraction over WebSockets and a simple request-response API gesture for answering HTTP requests. The Web API sample shows how to integrate Hybrid Connections with ASP.NET Core for web services.


The Hybrid Connections modules replace or amend existing Node.js modules with alternative implementations that listen on the Azure Relay service instead of the local networking stack.

The hyco-https module amends and partially overrides the core Node.js modules http and https, providing an HTTPS listener implementation that is compatible with many existing Node.js modules and applications that rely on these core modules.

The hyco-ws and hyco-websocket modules amend the popular ws and websocket modules for Node.js, providing alternate listener implementations that enable modules and applications relying on either module to work behind the Hybrid Connections Relay.

Details about those modules can be found in the azure-relay-node GitHub repository.

Next steps

To learn more about Azure Relay, visit these links: