is it also possible to run Cast apps on Chromecast without internet access in a local network only? Maybe with an own webserver. For a showcase event I can not ensure access to
As Leon says, the 'cast needs Internet access part of the time. Booting (I didn't know that!), and to resolve the AppID to the receiver app URL. Once the 'cast has the URL to load and had resolved the hostname in the URL to an IP address, it no longer requires the Internet, IF everything is set up correctly and on the local subnet.
For example, I develop cast apps at home. Lets say I registered my app and the custom receiver associated with it is at https://10.0.0.5/basil_app1/reciever.html
(or at a hostname that resolves in public DNS to the private IP 10.0.0.5, a hostname is what I actually use).
Then, if my app needs to load further media, it can reference it either by the already resolved hostname, or by IP, again served from the host at 10.0.0.5
It sounds a little like you're unclear on how to set up and interact with a private network and web server, which is not a Chromecast problem really.
For me, if I had to do a Chromecast demo at (for example) a customer site and was unsure of the network situation, I'd set up the Chromecast to use a private hotspot Wifi network provided by my cell phone, and have all the web resources needed served from my laptop, again configured on the private Wifi network. Again, not really a 'cast programming problem.
Chromecast requires an internet connection when it boots up and to load the receiver apps. Your media content can come from a local web server once the receiver app is loaded.
As of early February 2015 the Chromecast requires an internet connection to stream even local content (i.e. from your computer over your wifi).
The reason is that, to facilitate the media playback, special code (Javascript) is run directly from Google servers. Why can't Google just download this code directly to the Chromecast one time? I believe it has to do with security amongst other reasons (some nice and some not so nice)
The evidence? My internet goes down all the time, interrupting whatever I'm casting.
I have the following setup to cast from my PC to the chromecast using a mobile wireless connection.
Basically I have the PC and ChromeCast connected to a new wifi router ($25 belkin from Walmart). Initially, Chromecast yells at you because there isn't an internet connection. To kill the complaining from ChromeCast, simply install FoxFi on your mobile and PDANet on your PC. I've connected them via USB since the hotspot feature wont work with my carrier.
Once the connection has been established, you should see 2 connections on your PC and you can cast from PC to Chromecast. Watching netflix on it right now. Haven't tested from another device yet.
So....
Install:
-FoxFi on Samsung Galaxy S4
-PDANet on PC/Laptop
Connect:
- Samsung Galaxy S4 -> PC (via USB in my case)
- PC -> Local router
- Chromecast -> Local router
On your PC you should see 2 connections. The PDANet connection with internet access and the Local router with no internet access.
Also note that I initially installed the chromecast on my primary wifi that has internet access. No issues there, but just in case you try to get this method to work and it doesn't, maybe try setting it up on a router with inet access first, then switch to the non-inet router.