1. "It's a really difficult port, and we know because we've already done the server."
Notes is built using the principal of an abstraction layer between the code that's common to all versions of Notes and the specific hardware and Operating System. Inside Notes (at http://www-10.lotus.com/ldd/notesua.nsf/0b345eb9d127270b8525665d006bc355/ec73cbf1c6392ba385256856005bd224?OpenDocument) discusses the Notes multi-platform design as being a mixture of general and special case code, written in a portable language such as C or C++ and compiled for each platform, and of a virtual machine model, which is the implementation of the Notes runtime itself. The platform layer, the portable language piece, is quite low-level stuff, which it needs to be to give the developers the maximum flexibility and to keep it simple and fast. It's important that it's kept simple and atomic, so that the design model doesn't age and start being a barrier to development.

The Notes database part of the abstraction layer (Notes Object Services), the bit that deals with the physical storage of the Notes database and the part of the layer that interfaces to network Operating Systems and so on, are relatively simple pieces. Thus, they're relatively easy to maintain. But at the UI (User Interface) level, the platform layer is going to be much more complex, because graphical, windowing UIs are much more complex. Their design models aren't the same, which makes the development of an abstraction harder, much harder than, say, an abstraction layer that manages access to file systems.

Along the way, Lotus has to make the choice as to whether maintenance of a given platform abstraction will be supported by sales or sales projections. So even though Lotus has done quite a chunk of the Linux porting work, in that they have a Linux platform abstraction that supports the Domino server, this is the easy bit of the client port.

This is, I think, a large part of the reason why Lotus dropped all the Unix clients at the end of Notes 4.5, as well as a large part of why they haven't done a Linux Notes client. I've heard Bill Andreas, the Senior Designer at Lotus who was responsible for much of the UI of Notes R5 and 6, say that the UI abilities of some of the Notes platforms (he mentioned OS/2 specifically) are just too crude to enable the port to be done easily. As the UI demands on the Notes client grow, the port becomes harder to do. And the last thing anyone wants is to have the Notes client development held back on Windows--the major client platform--because UI capability is missing on one of the minor platforms.