by Tony Harris - Jenton Software

An Exercise in Taming the Unknown Giant with a Unknown Tool...

Lotus Notes is a large powerful groupware product - undoubtedly! However, using the in-built development language, or developing routines in C, can be very time consuming for those who just want the data...

I recently had the necessity to create an application that pulled data from a LOTUS Notes database, on a large Network, in order to create some reports required by the powers that be! Enter a nifty custom DLL available on CompuServe - VB-Notes!

This shareware DLL allows a VB developer to access the data in Notes (to do with whatever they wish - probably pull it out and push it into Access or maybe create a graph).

This customised suite of routines (function CALLs really) comes with a simple set of tools to open and close the Notes Database, start and terminate a Notes session, extract and modify data in individual fields on a Note, and retrieve a unique Note or series of Notes meeting a selected criteria. (If you're really a masochist - it also comes with C source code).

There are, however, a few addendums, quid pro quos and provisos, of course. i.e. Beware the free gift - it comes at your expense!

• Firstly, the developer must know the syntax for writing the dialogues for selecting Views from a Notes session, as the selection criteria in use by the GETNOTES function uses the Lotus syntax. So bone up on Notes selection formulae. One wrong move and your program is toast.

• The DLL comes with very little documentation - sparse would be a better word.

• The functions are extremely simple in their approach, consequently error handling is minimal. Specifically, for most calls it is limited to a returned value indicating success or otherwise. Successful calls also usually return a value as a string. Unsuccessful calls which are unattended usually crash the system unless you trap them on each occasion. Beware Be very aware.

• Memory management is also minimal - therefore what you specify in the call as a predefined buffer size is exactly what you get, but be careful because if you don't close the field, Note or DB within the appropriate time, or in the correct sequence, memory loss is imminent, if not guaranteed!

• All data returned by the functions is NULL-TERMINATED STRING format. This is extremely important if you are doing comparisons within the Notes database or if your are comparing values between Notes and ACCESS tables.
  If you are doing comparisons in NOTES only tables - leave the NULLs on the end of the strings!

  If you are using the return value to compare or select from ACCESS tables - remove the NULL from the end of the string. This can be done with;

    sReturn =Left$(Trim$(sReturn),Len(Trim$ (sReturn)-1))
  

  which will firstly remove all leading and trailing spaces (not NULLs) and then nip the single NULL character (ASCII 0 and ANSI 0) off the end of the string.

  This also means that if you want to use the Notes data everything must be converted to the correct type. Time and Date formats are tricky - remember to check your WINDOWS Control Panel International settings and then experiment.

• The working directory of your final program must be pointed at the NOTES sub directory and the path must include a pointer to the location of the standard NOTES DLLs. These are really recognisable by the preceding underscore in the name. e.g _NSF.DLL, _LIB.DLL

I saved the best for last...

• The DLL will not work in interpretive mode. This means that you must compile your program and test the EXE, you cannot test it by using the time honoured F5 button. If it crashes - all you can do is guess; unless you placed some nice MSGBOXes or created a logfile for debugging. The error messages this creates are euphemistically called GPFs - I called them frustrating.

Having said that you're probably wondering why I continued to use it in my project? - well, once you sort out these little idiosyncrasies - it actually works extremely efficiently. It uses very little memory and unlike more "commercial" products that hog disk space and runtime, it doesn't!

[HOME] [TABLE OF CONTENTS] [SEARCH]