6 OPC UA ObjectTypes ToC Previous Next

6.3 AliasNameCategoryType ObjectType Definition ToC Previous Next

6.3.2 FindAlias Method ToC Previous Next

The FindAlias Method allows a Client to obtain the list of Nodes that match the provided AliasName search string. The signature of this Method is specified below, the arguments are defined in Table 3.


[in]  String       	AliasNameSearchPattern,
[in]  NodeId			ReferenceTypeFilter,
[out] AliasNameDataType[]   AliasNodeList

Table 3 - FindAlias Method Arguments

Argument Description
AliasNameSearchPattern A string that can contain wild cards, use to find a list of AliasNames (see OPC 10000-4 - “Wildcard Characters” table for supported wildcards)
ReferenceTypeFilter A NodeId that represent a ReferenceType (i.e. AliasFor or one of its subtypes) that restricts the search. Any ReferenceType includes all subtypes of that ReferenceType.
AliasNodeList The returned list of AliasNameDataType. If no Nodes match the search string or have the appropriate ReferenceType, the list shall be empty.

Method result codes are defined in Table 4

Table 4 - FindAlias Method Error Codes

Result Code Description
Bad_InvalidArgument The input string is not a valid search sting
Bad_UserAccessDenied The current user does not have the rights required.
Bad_ResponseToLarge The response was to large to be returned, try new filter and repeat find

The Method is formally defined in Table 5.

Table 5 - FindAlias Method AddressSpace definition

Attribute Value        
BrowseName FindAlias        
References Node Class BrowseName DataType TypeDefinition ModellingRule
HasProperty Variable InputArguments Argument[] PropertyType Mandatory
HasProperty Variable OutputArguments Argument[] PropertyType Mandatory

It is important to note that there might be more than one entry for every AliasName. Multiple Servers might provide an equivalent object (such as a temperature sensor). This Method will return the AliasNames in order of preference. That is the Server will return what it recommends as the best match first followed by the next best match etc. The criteria for ordering are Server specific. The criteria might be based on the ServerStatus of the Server that contains the referenced Node, it might be load balancing of Servers, or it might be some other algorithm.

Clients should use the first usable entry in the list.

Previous Next