Local network discovery¶
Starting from v0.3 of the platform all everpl instances (everpl hubs) are able to be discovered in a local network by default.
Hubs announce their presence and can be discovered using a Zeroconf (Avahi/Bonjour) protocol - Zero Configuration Networking protocol. This protocol allows services to announce their presence in the system, to assign constant domain names in a “.local” domain zone, to resolve such domain names and to look for a specific service in the system.
For more information about Zeroconf you can read an article on Medium titled “Bonjour Android, it’s Zeroconf”. It tells about Zeroconf protocols in general, about Bonjour/Avahi approach and how it relates with client applications and service discovery.
Unfortunately, Zeroconf (and UDP multicast in general) isn’t supported by modern web browsers.
For more detailed information see:
- DNS-SD protocol website: http://www.dns-sd.org/, covers service discovery part of functionality;
- mDNS protocol website: http://www.multicastdns.org/, covers domain name association in “.local” domain zone;
- and corresponding RFCs.
For testing purposes you can use such handy tools as:
- Avahi-Discover GUI utility for Linux: https://linux.die.net/man/1/avahi-discover
- Service browser for Android: https://play.google.com/store/apps/details?id=com.druk.servicebrowser&hl=en_US
- dns-sd CLI tool for macOS
How to discover an everpl hub¶
In order to discover an everpl hub you need to use one of the Zeroconf
libraries (like build-in NSD for Android) and search for a service type
_everpl._tcp. By default such devices will have a name defined as
“everpl hub @ hostname”. To access an everpl REST API on a device you
can use name and port, defined in Hostname (Server) and Port fields of
a discovery response correspondingly.
Here is an example of a complete discovery response (as displayed by console avahi-browse utility):
= virbr0 IPv4 everpl hub @ hostname_was_here _everpl._tcp local hostname = [hostname_was_here.local] address = [192.168.20.1] port =  txt =