I've been looking at building a new GIS client for ArcGIS server and naturally took the newest api version - v4.0.
However I now realize that there is absoluty no support for OGC WMS layers. In 3.17 there was a WMSLayer class.
Is there any way to add industry standard OGC layers such as WMS [Web Map Service - Wikipedia, the free encyclopedia] as the api currently stands?
if you want OGC WMS layers then you need to use 3.17 of the JS API. WMS layer support is coming but there is much work to be done in the new JS API 4.0 yet.