IDEC WindSRV - Manual (Page 45)

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node (e.g. the units in a cell).
 QueryOrganization - Provides a way to determine if the underlying system is inherently flat or hierarchical and
how the server may represent the information of the address space to the client. Flat and hierarchical spaces
behave somewhat different. If the result is flat then the client knows that there is no need to pass the Branch or
Leaf flags to BrowseOPCItem IDs or to call ChangeBrowsePosition.
IOPCItemProperties
This interface can be used to browse the available properties associated with an Item ID as well as to Read the
properties' current values.
 GetItemProperties - Returns a list of the current data values for the passed ID codes.
 LockUpItem IDs - Returns a list of Item IDs for each of the passed ID codes if any are available. These indicate
the Item ID which could be added to an OPCGroup and used for more efficient access to the data corresponding
to the Item Properties.
 QueryAvailableProperties - Returns a list of ID codes and descriptions for the available properties for this Item
ID. This list may differ for different Item IDs. This list is expected to be relatively stable for a particular Item ID,
although it could be affected from time to time by changes to the underlying system's configuration. The Item ID
is passed to this function because servers are allowed to return different sets of properties for different Item IDs.
IOPCItemIO
The purpose of this interface is to provide an extremely easy way for simple applications to obtain OPC data.
 Read - Reads one or more values, qualities and timestamps for the items specified. This is functionally similar to
the IOPCSyncIO::Read method.
 WriteVQT - Writes one or more values, qualities and timestamps for the items specified. This is functionally
similar to the IOPCSyncIO2::WriteVQT except that there is no associated group. If a client attempts to write VQ,
VT, or VQT it should expect that the server will Write them all or none at all.
 Group - The client calls CoCreateInstance to create the Server object and the initial interface.
 QueryItnerface - The client can ask the object whether it supports any outgoing interfaces by calling
QueryInterface for IConnectionPointContainer. If the object answers "yes" by handing back a valid pointer, the
client knows it can attempt to establish a connection.
 AddRef - Increments the reference count for an interface on an object. It should be called for every new copy of
a pointer to an interface on a given object.
 Release - Decreases the reference count of the interface by 1.
IOPCGroupStateMgt
IOPCGroupStateMgt allows the client to manage the overall state of the group. Primarily, this accounts for changes
made to the group's update rate and active state.
 CloneGroup - Creates a second copy of a group with a unique name.
 GetState - Gets the current state of the group. This function is typically called to obtain the current values of
this information prior to calling SetState. This information was all supplied by or returned to the client when the
group was created.
 SetName - Changes the name of a private group. The name must be unique. The name cannot be changed for
public groups. Group names are required to be unique with respect to an individual client to server connection.
 SetState - Sets various properties of the group. This represents a new group which is independent of the
original group.
IOPCGroupStateMgt2
This interface was added to enhance the existing IOPCGroupStateMgt interface.
 SetKeepAlive - Causes the server to provide client callbacks on the subscription when there are no new events
to report. Clients can then be assured of the health of the server and subscription without resorting to pinging
the server with calls to GetStatus().
 GetKeepAlive - Returns the currently active keep-alive time for the subscription.
 IOPCItemMgt - IOPCItemMgt allows a client to add, remove and control the behavior of items is a group.
 AddItems - Adds one or more items to a group. It is acceptable to add the same item to the group more than
once, thus generating a second item with a unique ServerHandle.
 CreateEnumerator - Creates an enumerator for the items in the group.
 RemoveItems - Removes items from a group. Removing items from a group does not affect the address space
of the server or physical Device. It simply indicates whether or not the client is interested in those particular
items.
 SetactiveState - Sets one or more items in a group to active or inactive. This controls whether or not valid data