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Specialized Client Objects

A specialized client object builds provides functionality that is relevant for specific problem domain. It contains, in a sense, pre-packaged pieces of reusable code that the developer would typically need to write, whenever he needs to develop a solution for that problem domain.

In OPC Unified Architecture (OPC UA), the problem domain addressed by the specialized client object is often a selected part of the OPC UA specification.

QuickOPC exposes several useful specialized client objects to you, saving you from having to write unnecessary parts of code.

OPC UA Global Discovery Client

The OPC UA Global Discovery Client is a specialized OPC UA client object for global discovery. In the OPC UA specifications, the functionality covered by this type is described in Part 12: Discovery and Global Services, in the Global Discovery Server section.

The methods allow querying for applications and/or servers, and registering, unregistering or updating application registrations in the GDS.

OPC UA Certificate Management Client

The OPC UA Certificate Management Client is a specialized OPC UA client object providing access to certificate management (CM) information model of an OPC UA Global Discovery Server (GDS).

The methods allow getting certificate groups, requesting key pairs or certificate signing and obtaining the results, retrieving trust lists, and more.

OPC UA Client Application Service

The OPC UA Client Application Service is capable of maintaining client application registrations with one or more GDS servers simultaneously. It keeps track of the registrations (and unregistrations) performed. You can use this service to easily register your application with the GDS, and manage its certificates and trust lists.

This service works on even higher level than the specialized client objects - OPC UA Global Discovery Client and OPC UA Certificate Management Client. Instead of having to call the OPC UA methods as described in the specification, the client application service already puts together the necessary parameters, decides which method to call when, and then performs several operations at once. It also communicates directly with the application environment - it stores the certificate obtained from the GDS into the certificate store, refreshes trust lists, etc.

OPC UA File Transfer Client, and File Provider Model

The OPC UA specification allows servers to provide file and directories, resembling traditional file systems, as part of their information model, and QuickOPC allows to consume this functionality comfortably. QuickOPC gives you a specialized client object for easy execution all "File Transfer" operations, but not just that. QuickOPC also allows he OPC UA file be treated as normal .NET streams, so that your code can abstract from details of OPC UA when manipulating file contents. In addition, you can use the File Provider Model, which further generalizes how your application "sees" the elements of the OPC UA file system, making it possible to write programs that are independent of the type of file system they work with.

Available methods include:

  • Obtain information about specific files
  • Create, open and close files
  • Read data from and write data to files
  • Get and set position in the file
  • Delete files
  • Create and delete directories
  • Move or copy files and directories
  • List contents of directories
  • Finding files, directories, and finding a parent directory
  • Finding a file system on a specified OPC UA object
  • Determining whether the specified node represents a file or directory

Footnote & required disclosure: QuickOPC (including its Options) is a software development kit (SDK) for development of OPC clients. Installing QuickOPC or its Options does not change system settings.