Tag: Lotus Notes

A CRC is a number which is supposed to change accordingly to the string its computed upon. So it can be used to detect if the user made changes to a chosen subset of the fields of a document.

When saving the document, just join the text values of the fields in an ordered manner, then get the CRC of that string and store it as a new field value. When checking the document for changes to those fields, make the string again and get its CRC. If the saved CRC and the one just computed are equal, then you should be reasonably sure that those field values have not changed, but if the CRC does change, then you can be completely sure that those field have changed as well!

A CRC32 class comes with the java.util.zip package, and LS2J can be used to access and use it.

Here is the code for a Java library, name it CRC32 Java

And here is a LS2J wrapper, just for making it simpler to use in LotusScript. It’s a LotusScript library and you should name it CRC32

I’d like I could use parallel assignment in LotusScript. It’s the britghtest single programming concept I discovered in the past year, studying Ruby and other scripting languages.

It’s fairly symmetrical to the argument passing concept and it really enhances code readability.

Microsoft Office products like Word, Excel and Project can be accessed by LotusScript code running on a Windows machine through the OLE interface made available by the CreateObject function:

A handle to an OLE root object is a simple and mighty link to (almost) every property and method of the interfaced application.

Certainly not reachable are the constants, and I cannot guess any reason for this. MS Project 2003 has some 3,800 constants defined. All of them are well described in the online manual, but none of them is ever linked to any of the objects reachable from the root object. They are available from insibe the VBA macros, simply because MSProject is the object library and the VBA runtime generates an object for it. So the constant pjTimescaleDays, which is a member of the enumeration PjTimescaleUnit, is defined by the path

MSProject.PjTimescaleUnit.pjTimescaleDays

In fact VBA programmers are more lucky, because the VBA runtime makes an alias for each constant so that the last identificator is enough.

In my programs I could put Const pjTimescaleDays = 4, it’s just a matter of copy and paste from the Object Browser integrated in the VBA IDE. But this procedure can quickly become annoying, because the whole corpus of help articles and examples heavily rely on the VBA runtime aliasing feature. And if a Notes agent needs access to just a 10% of all of the available constants, then it’s really cumbersome to manually build the 400 lines of constants. And they are constant in a subtle way, i.e. until the product vendor suddenly change them.

To access constants defined in OLE applications the VBA Object Browser uses the Tlbinf32.dll library. Luckily enough this library is just another OLE application which can be directly used in LotusScript code.
It officially ships with Visual Studio, but if you haven’t got it already (it sould be in the windows system32 folder), you can download the Tlbinf32.dll library from afreedll.com.

a good article about the Tlbinf32.dll library
a useful manual for the Tlbinf32.dll library

Example

To show how you can load OLE constants and use them to effectively simplify and make your code selfdocumented, here is a simple agent for importing MS Project tasks into Notes documents.

Block 1: How to load OLE constants

Block 2: How to find the path to the object libraries

Block 3: How to import many Project fields at once

Installing the Tlbinf32.dll library

Before using its services, the Tlbinf32.dll library needs to be properly installed. This is done by putting its file in the windows system32 folder and then by registering it. This means that the user has to have administrator rights to their PC. As usual, you can implement the auto install feature for a needed file in a Notes database in three steps:

1. Attach the file to the About Database document and hide its paragraph
2. Add the @Command( [RunAgent]; “(Install Tlbinf32.dll)” ) to the Post Open event of the Database Script
3. Add the following agent to the database and name it (Install Tlbinf32.dll)