There are no hostnames nor views in App+Web properties. All web-based traffic will come through as web data streams. You configure your streams in the Data Stream section of the settings. More about that here.
The equivalent of hostname is Stream Name, however, this is not available in the reporting configuration. To filter a report based on a unique stream, you will need to use Stream ID in the exploration report. See here for more detail.
Stream can be found referenced in the admin section under ‘Data Streams’ and also as a dimension in the exploration reports- though sometimes they represent different things depending where they are used.
Under ‘Data Streams’ in settings
After selecting your stream it will show you the details of the stream.
Stream URL – http://datarunsdeep.com.au – the hostname for where the data is coming from
Stream ID – 123456789 – A number identifying the stream of data
Stream Name – Data Runs Deep – The name given by the user who configured the stream (this is different to the stream dimension – explained later)
Measurement ID – G-1A2B3C4D5E – The identifier for where the data is sent – just like the UA ID in Google Analytics
So in Universal Analytics you can use the hostname in your reports as a primary or secondary dimension. App + Web is a little different.
When searching for dimensions only the Stream ID and Stream Name are available.
As a dimension
Interestingly the Stream Name is used differently as a dimension – it is referring to whether it is app or web. Currently there is no option to pull in the same Stream Name we see in the settings section nor is there an option to bring in hostname. This is likely something you need to manually configure.
Hopefully in the near future this will become a part of the base dimensions and won’t need to be manually configured.