OpcLabs.EasyOpc.UA.LiveMapping Namespace

This namespace contains classes used for live mapping of OPC Unified Architecture (OPC-UA) sources to targets.

Classes

	Class	Description
	UAClientDataMapping	A data mapping based on OPC Unified Architecture (OPC-UA) specification.
	UAClientDataMappingSource	A mapping source for data in OPC Unified Architecture (OPC-UA) specification.
	UAClientMapper	A client mapper for OPC Unified Architecture (OPC-UA) specifications. Provides a functionality to map an object to entities in OPC-UA domain.
	UAClientOperationContext	A context for OPC-UA client operations.
	UADataAttribute	Gives information about OPC Unified Architecture (OPC-UA) data.
	UADataChangeFilterAttribute	Defines the conditions under which a data change notification should be reported.
	UAEndpointAttribute	Gives information about an OPC-UA endpoint, such as the endpoint's URI.
	UAMappedNode	A pre-made base class for mapping OPC Unified Architecture (OPC-UA) nodes. Contains commonly used meta-members.
	UAMapping	A mapping based on OPC Unified Architecture (OPC-UA) specifications.
	UAMappingContext	A mapping context for OPC Unified Architecture (OPC-UA) specifications.
	UAMappingProvider	A mapping provider for OPC Unified Architecture (OPC-UA) specifications.
	UAMappingSource	A mapping source for OPC "Classic" specifications.
	UAMemberAttribute	Denotes that the member should be involved in OPC Unified Architecture (OPC-UA) mapping.
	UAMemberMappingDefinition	Member mapping definition for members involved in OPC Unified Architecture (OPC-UA) mapping.
	UAMonitoringAttribute	Gives information about how the OPC Unified Architecture (OPC-UA) subscription should be performed, such as the sampling interval.
	UANamespaceAttribute	Specifies the OPC-UA namespace to be used.
	UANodeAttribute	Gives information about OPC Unified Architecture (OPC-UA) node.
	UANodeIdTemplateAttribute	Describes how to construct OPC-UA node IDs.
	UAReadAttribute	Gives information about how OPC Unified Architecture (OPC-UA) reading should be performed.
	UASubscriptionAttribute	Gives information about how the OPC Unified Architecture (OPC-UA) subscription should be performed, such as the publishing interval.
	UATypeAttribute	Denotes that the type should be involved in OPC Unified Architecture (OPC-UA) mapping.
	UATypeMappingDefinition	Type mapping definitions for a type that is mapped to OPC Unified Architecture (OPC-UA).

Enumerations

	Enumeration	Description
	UADataMappingKind	Specifies how the OPC Unified Architecture (OPC-UA) data will be mapped.
	UADataMappingOperations	Possible mapping operations on OPC Unified Architecture (OPC-UA) data.

Remarks

The live mapping development model allows you to write objects that correspond logically to a functionality provided by whatever is “behind” the OPC data. For example, if part of your application works with a boiler, it is natural for you to create a boiler object in the code. You then describe how your objects and their members correspond to OPC data – this is done using attributes to annotate your objects. Using Live Mapping methods, you then map your objects to OPC data, and perform OPC operations on them.

For example, when you subscribe to OPC items (in OPC Classic) or OPC attributes (in OPC-UA), incoming OPC notifications about changes can directly set corresponding properties in your objects, without any further coding. You can then focus on writing the code that handles these property changes, abstracting away the fact how they come in.

Note: Some mapping technologies for.NET already exist, from Microsoft or otherwise. These technologies are mainly focused on mapping database information (ORM – Object-relational mapping), and they are not well suitable for automation purposes like OPC. We therefore had to implement a new mapping model. We use the term “live mapping” so that it is clearly distinguished from other mapping technologies used; it also reflects the fact that this kind of mapping is well-suited for real-time, “live” data.

Do not confuse the live mapping model with live binding, also provided by QuickOPC. The main differences between the two are that

live mapping is primarily non-visual (both in design and in runtime), and
live mapping has the ability to work with object types, not just individual members.

With live mapping model, you generally need to do following steps in order:

Write classes that are a logical model of your application. If you are following object-oriented principles in your design, chances are that your code already has such classes anyway.
Annotate the classes with attributes for live mapping. The main purpose of these attributes is to describe how the members of your classes correspond to nodes in the OPC address space.
Create instance(s) of your classes, as usually.
Perform the actual mapping, which associates your objects with OPC data.
Call mapping operations as needed, e.g. execute OPC reads, writes, or subscribe to changes in OPC values.

The features discussed here, or some of them, may not be available in all editions of the product. Check the QuickOPC Product Editions page for differences between the editions. The trial license has all features enabled (and is limited in period for which it provides valid data), but licenses for specific commercial editions may have functionality limitations.

Reference

OpcLabs.EasyOpcUA Assembly