Selecting a Linkage Protocol
View Related Video: User Defined Functions - Introduction
Connector in Microsoft Excel provides the ability to use either Dynamic Data Exchange (DDE) or User Defined Functions (UDF) as the data transfer protocol between Microsoft Office and CaseWare Working Papers.
The UDF protocol offers enhanced functionality over DDE, and to take advantage of Connector's full functionality, it is recommended that UDF be used. By default, UDF is enabled as the default information protocol.
Comparing linkage protocols
| DDE links | UDF links | |
|---|---|---|
| Syntax |
DDE formulas in Excel consist of three separate parts: cwin32|Data!'CWEval|active|act("BR","S71")|'
DDE formulas in Word simply consist of a call to the function: act("BR","S71") For more information on DDE functions, see here. |
UDF formulas simply consist of a call to the function: cw_act("BR","S71") For more information on UDF functions, see here. |
| Active Working Papers Sessions | Requests for information are not tied to a specific client file by default, imposing the condition that only one session of Working Papers may be active while working with Connector. | Multiple instances of Working Papers can be active without compromising the stability of Connector linkages. This allows the user to work in the active year client file while also keeping the prior year client file open for reference in a second instance of Working Papers. |
| Link Evaluation | Connector helps insert the link to Excel/Word, but does not evaluate the link. Working Papers must be running for the link to be evaluated. | Connector inserts the link and establishes a connection to evaluate the link. Working Papers must be installed, but does not have to be running. |
| Vulnerability | Excel/Word tries the DDE clients of all running applications while searching for the running Working Papers. May cause Excel/Word to stop responding. | Evaluation depends on CaseWare software only. |
| Referencing | Cannot use Excel's references in formulas. | Can use Excel's references in formulas. |
| Linking to Client File | Can use a client file path or GUID to specify a particular client file from which to retrieve the values. However, it must be specified in each link, which requires editing each link manually to change the client file path GUID. If the client file path or GUID does not exist, Excel might stop responding. |
Has an optional parameter where a client file can be specified by path, GUID, or reference to the cell where the client file path or GUID were defined. The reference allows redirecting all links to another client file by changing one cell only. If the client file path or GUID does not exist, Connector reports an error with an explanation. |
| Editing | Linking a set of formulas to a column of IDs will require inserting all the links one by one. | Can copy and paste the formula to the next cell in the formula column and Excel will update the cell’s reference to the ID of the row. |
Notes
- It is recommended that DDE links be converted to UDF by following the Linkage Protocols: DDE to UDF Link Conversion instructions.
- UDF can be disabled under Tools | Options. Remove the checkmark beside Use Connector User Defined Functions (UDF). Ensure that all installations in the firm have this option deselected. Instructions for disabling this option during installation can be found in the Connector Getting Started Guide.
- Formula length is dictated by the character limit for a cell in Excel.
See the Excel help topic Excel specifications and limits for information about the various limits applicable to the version of Microsoft Office being used.
