registerPoint

registerPoint — registers to receive updates from a Cascade DataHub point.

Syntax

For C++:

ST_STATUS registerPoint(CDataHubPoint&  point,
 bool  create=TRUE);
ST_STATUS registerPoint(LPCTSTR  pointname,
 bool  create=TRUE);

For Java:

Exception registerPoint(DataHubPoint  point,
 boolean  create);
Exception registerPoint(String  pointname,
 boolean  create);

For C#:

Exception registerPoint(DataHubPoint  point,
 bool  create);
Exception registerPoint(String  pointname,
 bool  create);

Parameters

point

A DataHubPoint object. The name member must be valid.

pointname

The name of the point.

create

If TRUE, then the point is created if it does not already exist. If FALSE and the point does not exist, then an error message will be generated.

Returns

For C++:

    ST_OK if the command was successfully sent to the DataHub. Since the command is sent asynchronously, the actual success or failure of the command must be determined through the onSuccess or onError message handlers.

    ST_NO_TASK if a connection to the DataHub does not exist.

    ST_ERROR if the connection socket is unable to send the message.

Description

When a point is registered with the DataHub, any changes to the value of that point in the DataHub will cause the onPointChange method to be called. If the DataHub point does not exist, then the DataHub will respond with an error, and onError will be called with the following arguments:

status: ST_NO_POINT
msg: "Point does not exist"

See Also

writePoint, unregisterPoint, createPoint, registerDomain