[ale] difference between android and linux ?

Sat Aug 13 17:49:10 EDT 2011

I want to say thanks to Pat R, Tavarvess W, James S, Jim K, Michael T, 
and others who have responded to this inquiry to try to clarify things.  
It IS a bit confusing.  I want to review each of your replies in more 
detail, but for now, I have a few more questions.  What I'm getting from 
the discussion is that you first have "the core" or the Linux kernel on 
GNU Linux and on Android Linux.  Serving comparable duty would be the NT 
Kernel in Windows and the Mac OSX Kernel on Mac.  Then, wrapped around 
or sitting on top of the Kernel are various libraries and functions 
which make up the API of the OS which applications can call on.  Then, 
you have the applications themselves which call on the API to get things 
done.

At a binary level, applications for Windows, Mac, GNU Linux, and Android 
Linux are not compatible with each other.  Even on machines with 
comparable and adequate resources, the API's, functions, and libraries 
are too different among the various systems, in general.  So, Firefox 
for Ubuntu is fundamentally different, even though functionally the 
same, than for Windows or Mac (if available), for example.

Even various binary executables for different GNU Linux systems may be 
fundamentally different.

Full desktop OS's like Ubuntu generally will not run on something like 
an Android tablet due to resource constraints.  A more stripped down 
version of GNU Linux may be able to run on a tablet with decent hardware.

I'd like to propose a hypothetical development scenario and gather 
opinions on what factors will affect the developer.

I'm making up this scenario, so it may or may not ever happen.  Let's 
say that I want to create a great application for stellar cartography.  
Let's say the user should be able to use a menu and form query system to 
select star charts and view them in windows or print them.  Let's say 
that there are various calculation functions included, so you can find 
out how far it is from various points in the galaxy in three 
dimensions.  Let's say you can also do things like calculate the 
cumulative mass of stars in various nebulae and generate reports and 
graphs on this data.  As I said, I'm just making this up, and I'm not an 
astronomer.  The point is, that this application, like many, will have 
(at least) a GUI UI component, a logic and calculation component, a 
database component, and perhaps an output component (printing) other 
than the GUI.  Let's say I want this application to work on Windows, 
Mac, Android Linux, and the top 5 flavors of GNU Linux.  A quick check 
of distrowatch.com says those are Ubuntu, Mint, Fedora, Debian, and 
SUSE.  Nothing against the others, but developing for 8 OS's is probably 
enough of a challenge for now.  The application has to be functionally 
identical on each system.  We could make allowances for UI design guides 
and traditions on each, but might choose to make them all exactly the 
same as well.  The executables may be different, but the data files the 
app creates, loads, and saves must be compatible across all systems.  A 
user must be able to use the app on any of the mentioned systems and do 
exactly the same things, or transport data from any system to any 
system.  Code reuse must be maximized among different versions, since I 
don't want to spend 8X the time it would take to make one version.

Putting aside what it actually takes to design a stellar cartography 
application, I want to address what it takes to set up the development 
environment.  I had read somewhere that you can maximize portability 
among apps by breaking them into the UI, logic, and database sections, 
which is why I structured this the way I did.  I added an output section 
because it seemed logical and appears that that would encompass a major 
subsystem.  The stuff I read said that if each subsection is built as a 
black box, so to speak, with a clearly defined IO interface at its 
boundary, then you could share some black boxes among multiple systems 
and customize others for each system.

Now, as far as I know, C++ standards based compilers are available for 
each platform, although I'm not totally sure about Android.  Assuming 
that's true, then I should be able to make the logic and calculations 
"box" identical for each system, with exactly the same code.

It appears to me that the other "boxes", UI, database, and output; would 
have to be customized to each system, based on the API that each is 
presenting.  So that makes it sound like my code reuse factor is taking 
a beating, with somewhere in the range 25% of code that is common and 
75% of code that is unique for each system.  However, it also seems that 
I may be able to get some help from libraries, such as FLTK or QT, which 
are available on different systems.  If such things are available on all 
these systems, then I can write my app to call the API of the add on 
libraries only, and avoid native OS calls.  That way, I would think that 
I could get my code reuse up to the range of 75% of code that is common 
and 25% of code that is unique to each system.  More common and less 
unique is obviously better.

I'm trying to set up a development system which will let me do exactly 
the type of thing I've described, when I'm ready for it.  What I don't 
want is a system that forever prevents me from porting my apps to other 
OS's.  Thus far, I'm thinking GNU tool chain (G++, GCC, GDB, MAKE, 
etc.).  I know this is available on GNU Linux systems and on Windows, 
although I don't know how to install it on Windows at this point.  I 
don't know for sure if it's available on Mac or Android.  I don't own a 
Mac or an Android device at this moment, so I cannot test that.  I'll 
probably use VIM for editing.  It would be nice if I can do equivalent 
development on any platform, but, if I'm stuck to developing on a 
specific system, that's OK.  I just have to be able to compile 
applications that will run on each system.  I'm thinking FLTK to start 
as a GUI library.  It's available on Windows and GNU Linux.  Again, not 
sure about Mac and Android.  Maybe later, I'd advance to something more 
comprehensive.  I don't know about database libraries and printing 
libraries.  Maybe MySQL, etc.

So, I'd like any advice I can get as to how to build a TRULY cross 
platform development environment, which can service all the OS's I 
mentioned.  Not that I'm ready to publish such an app, nor will I be in 
the near future, but I want to be eventually capable of it.

I just had another idea, which may be great or crazy.  Let's say I 
encapsulate my app within a VM, even if it is not visible to the user.  
Let's take for example, the VM that VirtualBox (or VMWare) presents.  
These systems emulate a specific set of hardware every time.  So, 
assuming I could get the VM "player" modules on each target platform as 
part of my app installation, I could just target whatever "machine" API 
is being presented to my program by the VM player.  I write code solely 
to the virtual machine, and ignore whatever is going on in the real 
machine.  Any resources available on the real machine should be 
presented to my app through the VM player's API.  Great... or crazy?

Sometime later, we can talk about version control, IDE's, and packaging 
and publishing for the various OS's.  As usual, any advice is greatly 
appreciated.

Sincerely,

Ron

On 8/12/2011 6:21 PM, James Sumners wrote:
> I'm not going to try and trim all of this on an iPad, sorry. But I 
> want to throw my two cents in on the Android and Ubuntu are Linux 
> variants.
>
> Ron, I don't know what distributions you are familiar with, but I 
> think you use Ubuntu. Try using Debian proper in a VM and see if you 
> can spot the differences. Ubuntu is a direct "variant" of Debian, and 
> I think you'll find that the two operating systems are _very_ 
> different. They are both "Linux" in that they are both based on the 
> Linux kernel from kernel.org <http://kernel.org>. But they are not the 
> same operating system.
>
> Another test would be to install CentOS in a VM. The difference 
> between it and Ubuntu is not at all subtle.

<snip>

> -- 
> James Sumners
> http://james.roomfullofmirrors.com/
>
> "All governments suffer a recurring problem: Power attracts 
> pathological personalities. It is not that power corrupts but that it 
> is magnetic to the corruptible. Such people have a tendency to become 
> drunk on violence, a condition to which they are quickly addicted."
>
> Missionaria Protectiva, Text QIV (decto)
> CH:D 59

-- 

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new messages very quickly.)

Ron Frazier

770-205-9422 (O)   Leave a message.
linuxdude AT c3energy.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.ale.org/pipermail/ale/attachments/20110813/0199c8b6/attachment.html 