OPC UA Local Discovery Server 1.03

---

What is a Local Discovery Server (LDS)?

The Local Discovery Server (LDS) A UA Local Discovery Server is the equivalent of OPCENUM (in OPC Classic) and is responsible for providing a list of UA Servers/Gateways that are accessible on the PC where the LDS is installed. is a DiscoveryServer that maintains a list of all OPC UA Servers and Gateways available on the host/PC that it runs on, and is the OPC UA equivalent to the OPC Classic OPCENUM OPC Classic service responsible for returning a list of OPC Classic Servers installed on the local PC. This service was a work-around for the inability to remotely access the Windows registry back in the late 1990's. interface.

How does an LDS work?

An LDS is a service that runs in the background. UA Servers An OPC Server exposing an OPC UA interface. will periodically connect to the LDS and Register themselves as being available. This periodic activity means that the list of available OPC UA servers is always current and means that an OPC UA client can immediately connect to any of them.

What is mDNS?

"mDNS" (ZeroConf) is a multicast protocol that allows servers to announce themselves on a LAN. The LDS is integrated with mDNS which means that it will automatically announce all OPC UA servers that have registered with it. The LDS also maintains a cache of all OPC UA servers on the LAN which have announced their presence and an OPC UA client can browse this cache by calling the FindServersOnNetwork service.

What does the LDS work with?

The LDS is developed with ANSI C to be platform independent Application source-code that can be compiled to work on different platforms such as Windows, Linux, iOS, Android, or embedded etc.. Current offerings (from the OPC Foundation) include release version for Microsoft Windows only.

Available from: www.opcfoundation.org/ua/lds

The LDS will work with any OPC UA compliant Server and Client.

How is this help structured?

This document will describe key-concepts that apply to an LDS, and will also show platform-specific information applicable to Microsoft Windows and Linux environments.