Re: Installer UI advices

[M. Uli Kusterer]

At 11:40 Uhr +0100 12.03.2005, Markus Hitter wrote:
> Actually, .dmg's are no archives at all, they are disk image files.

 Yes, of course. Adrian's comment sounded like .DMGs contained some 
special magic that was what made drop-installs possible, I just 
wanted to clarify that: All a disk image does when it comes to 
software distribution could be done similarly with any other kind of 
archive.

 In fact, from a usability standpoint, disk images are worse, because 
the concept of a "disk images" requires that the user understand the 
concept of a "virtual disk". Just treating it like any archive, which 
is a file that wraps up downloaded files in a space-saving way, 
requires less mental effort and learning on the user's part. And the 
less users have to think when using the UI, the more brain power is 
available for the tasks they're actually trying to achieve by using 
the computer.

> > You can do drop-install with apps from zipped archives, or .tgz 
> > ones just as well.
>
> Goal would be not to require any installation at all. With the .dmg 
> mounted, you can run most well designed apps right off the mounted 
> volume, without copying anything anywhere.
>
> I do this quite often and after a few runs to figure whether this 
> new app fits my needs or not, I possibly drag it over to a more 
> appropriate place for long term usage. But most apps I try out 
> disappear as soon as I unmount the .dmg. I was interested in testing 
> but have no further use for them.

 Yes, this would be the ideal case. But again, you don't need a disk 
image for that. A .ZIP archive would work just fine. You unpack the 
archive and run the app. All a .DMG does is add an intermediate step 
where the app is unpacked to a bit of RAM as you're running it. And 
for the reason mentioned above, I think .DMGs are not a facility 
worth emulating.

> > This scheme is only used for apps that don't require additional files.
>
> It should be highly encouraged to design apps this way, even at the 
> cost of some duplicated files/libraries/whatever. It makes handling 
> the software so much easier and you won't have any headaches with 
> different version requirements for the same framework/library.

 Yes, I fully agree. The self-contained-package-approach is very 
desirable. But due to GNUstep's Linux/Unix underpinnings, there are 
currently pieces of infrastructure in place that require certain 
files to be in certain places.

 Now, imagine we used an "on-launch-installer"-approach as discussed 
in other messages for more complex projects that need this feature: 
It'd install symlinks to the necessary files in those system 
directories, and complex applications could be used like any other 
GNUstep application.

 Admittedly, symlinks are too brittle for this to work in an optimal 
fashion (move the app, and the symlink goes dead), but maybe there 
are alternatives in Linux or Unix that perform a similar function?

> For files elsewhere on the disk - design your app to avoid them. 
> Generate temporary files as you need them. Generate preference files 
> when it's time to store something. Try not to fiddle with system 
> files, i.e. those in /etc.

 For most end-user apps, these recommendations will work. But for 
some apps, like those that talk to special hardware, or developer 
tools that need access to special hooks, we'll still need to mess 
with system files. This won't change until someone puts GNUstep and a 
GNUstep desktop on top of a specially modified operating system.

 The advantage of built-in installers is that there could be special 
GNUstep packages for GNU software. Like some people are using Apple's 
PackageMaker to create installer packages that install a new version 
of PHP. It would be away to quickly port any FOSS project to GNUstep. 
Embed it in an AppKit-based configuration app, and installation is as 
easy as copying one file to your hard disk and launching it.

--
Cheers,
M. Uli Kusterer
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