The main idea of the view model composition is taken from Mauro Servienti's implementation.
The code samples provided here are a simplified version of the composition engine.
The example here shows Server-Side UI Composition by taking advantage of ASP NET Core's, IAsyncResultFilter to tie into the rendering pipeline of the view.
The example also utilizes the ExpandoObject and dynamic to compose the view model. Useful link: http://www.siddharthpandey.net/use-newtonsoft-json-dynamic-expandoobject-objects/
The example uses Json Serialization for the data.
The first part, CompositionWithoutEvents demonstrates a simple UI composition where data from multiple services are composed during a HTTP Get request. The second part, CompositionWithEvents demonstrates adding messages using NServiceBus.
Any suggestions to improve this are welcome. Feel free to raise PRs or issues to make this better.