OPC Historian .NET Server Toolkit Reference
IBrowserDBA Interface Methods

For a list of all members of this type, see IBrowserDBA members.

Public Methods
 NameDescription
 MethodChangeBrowsePositionChange the current branch. This method provides a way to move up or down relative to the current position, or directly to a given position in a hierarchy.  
 MethodCreateBrowserCreate a new browser object with the specified filters, operators and attributes. The filters will be applied to all method calls to this instance of the browser. The server is expected to validate the filter arrays. The server must support a single client having simultaneous access to multiple browse interfaces. Filtering is optional behavior for a server. If a server does not support filtering, or only supports filtering on some of the requested attributes, the server shall return an interface to a browser which is only filtered on the accepted attributes. A server which does not support filtering shall return a pointer to an unfiltered browser interface. Filter operations are additive. To successfully pass filter criteria, the item must successfully satisfy all of the filter criteria. Implementation of filtering and browsing is server specific, however it is anticipated that servers with hierarchical name spaces may only apply filters to leaves, causing them to return branches which have no leaves which satisfy the criteria. It is anticipated that a client may create one browser to locate a particular area of the hierarchy, obtain a fully qualified branch name using GetBranchPosition, then pass that branch name to another browser which is using a different filter set. Servers may optionally support wild cards for string filters. To represent a single character the “?” shall be used. To represent multiple characters the “*” shall be used.  
 MethodGetBranchPositionGet the fully qualified name of the current branch.  
 MethodGetEnumEnumerate the nodes at the current branch. This method returns a string array with a list of leaves, branches, or ItemIDs, depending on the browse type requested. Whether a branch is an ItemID is undetermined and may be server dependent. The members of the enum set will be determined by the position of the browser in the server address space and the value of the filters when the browser interface was created. If no ItemIDs pass the filter criteria, the enum set is empty. Thus, a server which has a flat namespace would always return an empty array when asked for a list of branches, and it would return the same list whether it was asked for leafs or ItemIDs, since all of its Items are, by definition, leafs.  
 MethodGetItemHandlesThe item data file is checked and the handle stored in the handle list. The list index is returned as the server handle ///  
 MethodGetItemIDGet the fully qualified item ID. This method provides a way to get a fully qualified item identification. This is required since the browsing method return only the components or tokens that make up an ItemID and do not return the delimiters used to separate those tokens.  
 MethodReleaseItemHandlesThe item handle is closed. The handle list element is not removed to prevent index changes.  
 MethodValidateItemIDsThis method validates that specific HDA item IDs are known to the server.  
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See Also

Reference

IBrowserDBA Interface
I_HDAPluginDBA Namespace

 

 


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