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RTD-API-Functions.md

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◀️ | ▶️

RTD API Functions

⚠️ Note:

RTD functionality can only be used from the Excel's Worksheet (i.e. using these calls in VBA code will not work).

qRtdOpen

Function used to open a RTD connection to a kdb+ process:

String qRtdOpen ( alias, hostname, port, username, password )

where:

  • alias [String] - alias name that should be assigned to the connection currently being opened; this alias can later be used by other functions to reference specific connections (as multiple connections can be opened from the same Workbook object)
  • hostname [String] - name or IP address of the host to which connection should be opened
  • port [Int] - port number of q process to connect to
  • username [String] - username used to connect to q process
  • password [String] - password used to connect to q process

Returns either:

  • alias associated with currently opened connection - in case opened successfully
  • description of error - in case connection could not be established

The connection is opened only once. When using the same alias for all subsequent function calls, the same existing connection will be used.

Note:

To force re-opening of the connection use different alias.

Examples

qRtdClose

Function used to correctly close the connection associated with given alias:

String qRtdClose ( alias )

where:

  • alias [String] - closes the connection associated with given alias

Returns string Closed if connection closed successfully or error description in case of failure.

Examples

qRtdConfigure

Function used to configure various aspects of RTD server behaviour:

Object qRtdConfigure ( paramName, paramValue )

where:

  • paramName [String] - name of parameter to be configured; currently supported configurable parameters are:
| Parameter name      | Parameter type | Description                                   | Default value |
|---------------------|----------------|-----------------------------------------------|---------------|
| sym.column.name     | String         | Name of the column containing primary         | sym           |
|                     |                |    instrument identifier (so called symbol)   |               |
| function.add        | String         | Name of the function that should be present   | .u.add        |
|                     |                |    on q process allowing addition of          |               |
|                     |                |    instruments to current subscription list   |               |
| function.sub        | String         | Name of the function that should be present   | .u.sub        |
|                     |                |    on q process allowing subscription         |               |
| function.del        | String         | Name of the function that should be present   | .u.del        |
|                     |                |    on q process allowing removal of the       |               |
|                     |                |    instruments from current subscription list |               |
| data.history.length | Int            | Length of the history vector                  | 1             |
  • paramValue [Object] - value of the parameter to be set

Returns value of the parameter in question. In case it has been correctly set, it will be equal to ParamValue otherwise will return old value of the parameter.

Examples

RTD

Function used to subscribe to certain value from within a cell in workbook so that it automatically gets populated with new values as soon as they are available:

Object RTD ( progID, server, topic1, topic2, topic3, topic4, topic5, topic6)

where:

  • progID [String] - ID of RTD server implementation; should be set to qxlrtd; required
  • server [String] - not used; required
  • topic1 [String] - connection alias returned via qSubscribe; required
  • topic2 [String] - name of the table from which instruments should be subscribed; required
  • topic3 [String] - instrument name; required
  • topic4 [String] - column name within the table to which the subscription is being made; required
  • topic5 [String] - history index; optional - only needed when Topic3 equals back tick symbol (`); when filling Topic6 we have to have Topic5 (can be empty)
  • topic6 [Number] - Symbol Mapping; optional

Note:

Since Topic6 can be used only for back tick subscription, system cannot determine where to put data for particular symbols. That is why Topic6 has been introduced – it is used to map incoming symbols to numbers. First symbol which is delivered from database is mapped with first empty number of Topic6 and it stays mapped until all RTD formulas with given value of Topic6 are present in the sheet.

Updates the content of cell to which this function call is linked with the value matching subscription criteria.

Examples