What is the difference between the newly release ASP.NET WebHooks and Signal-R? What are the advantages or disadvantages? What are the use cases for each technology?
It really depends on service you want to integrate with and how. WebHooks is a simple pattern for integrating event notifications across different SaaS services. If the service you want to integrate with supports WebHooks then you can use that. If it supports SignalR then you can use that. In that sense the two are quite complementary.
Check Henrik F Nielsen post at http://blogs.msdn.com/b/webdev/archive/2015/09/04/introducing-microsoft-asp-net-webhooks-preview.aspx