Difference between revisions of "uaCap:Discovery Intro"

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(Created page with " === Server === All Servers have to support a discovery endpoint that provides Clients the following usages: * Locate Servers on the local host (Local Discovery): Clients can...")
 
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Discovery allows Clients to find OPC UA Servers, their supported protocols, security policies and other capabilities.
=== Server ===
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An OPC UA Client wishing to connect to an OPC UA Server needs the address of the Server. Client and Server can be on the same host, on the same network or even on completely different locations in a
 
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system (a plant, an enterprise). Servers may be installed on many different types of host devices like a sensor, a control device, or a workstation. A single device may host more than one Server.
All Servers have to support a discovery endpoint that provides Clients the following usages:
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[[File:UA fw Discovery.JPG|300px|left]]
* Locate Servers on the local host (Local Discovery): Clients can detect and choose end points of OPC UA servers located on the local host.
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* Locate Servers on a known remote host (Remote Discovery): This is for clients that know the name of the remote target host. Clients can use the host address to discover the Servers on this remote host.
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The OPC UA discovery process allows Clients to find Servers on the network and then discover how to connect to them. The information required to connect is provided in the form of an endpoint. An
 
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endpoint includes information about the address, the protocol to use, the manner to encode data and security level.
=== Client ===
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<br>
 
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Servers may have multiple endpoints if they support multiple addresses, protocols, or multiple levels of security. Clients can discover these endpoints and choose the proper one based on a system-wide policy or based on manual selection.
Clients may be pre-configured by some out-of-band mechanism. Without pre-configuration, Clients have to support the following discovery mechanisms:
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<br>
* Allow manual entry of a DiscoveryUrl.
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Note -
* Use FindServers Service to obtain the DiscoveryUrls of Servers on the local or a remote host.
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Discovery is specified in OPC UA Part 12, the Discovery Services are specified in OPC UA Part 4
* Use FindServersOnNetwork to obtain the DiscoveryUrls of Servers on the same multicast Subnet.
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* Discover a Server's Endpoint using the Server's DiscoveryUrl.
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Revision as of 10:06, 1 February 2015

Discovery allows Clients to find OPC UA Servers, their supported protocols, security policies and other capabilities. An OPC UA Client wishing to connect to an OPC UA Server needs the address of the Server. Client and Server can be on the same host, on the same network or even on completely different locations in a system (a plant, an enterprise). Servers may be installed on many different types of host devices like a sensor, a control device, or a workstation. A single device may host more than one Server.

UA fw Discovery.JPG

The OPC UA discovery process allows Clients to find Servers on the network and then discover how to connect to them. The information required to connect is provided in the form of an endpoint. An endpoint includes information about the address, the protocol to use, the manner to encode data and security level.
Servers may have multiple endpoints if they support multiple addresses, protocols, or multiple levels of security. Clients can discover these endpoints and choose the proper one based on a system-wide policy or based on manual selection.
Note - Discovery is specified in OPC UA Part 12, the Discovery Services are specified in OPC UA Part 4