The discovery process allows Clients to find Servers on the network and then discover how to connect to them. Once a Client has this information it can save it and use it to connect directly to the Server again without going through the discovery process. Clients that cannot connect with the saved connection information should assume the Server configuration has changed and therefore repeat the discovery process.
A Client has several choices for finding Servers:
- Out-of-band discovery (i.e. entry into a GUI) of a DiscoveryUrl for a Server;
- Calling FindServers on the LDS installed on the Client host;
- Calling FindServers on a remote LDS, where the HostName for the remote host is manually entered;
- Calling FindServersOnNetwork (see OPC 10000-4) on the LDS-ME installed on Client host;
- Supporting the LDS-ME functionality locally in the Client.
- Searching for Servers known to a GlobalDiscoveryServer. The DiscoveryUrl provides all of the information a Client needs to connect to a DiscoveryEndpoint (see 4.3.3).