[squeak-dev] OSProcess capabilities on Windows

Hi

Today I've been playing with OSProcess and CommandShell, to see if they
can give me the control I'd like for running external processes on Windows
(XP, then later Vista).  The VM I'm using is a somewhat customised
Web-browser plugin based on 3.7.  The image is a pretty heavily customised
3.7.

The plugin I built today seems to be working, and with a bit of tweaking
I've successfully launched batch-file commands from the Squeak shell or by
talking directly to CommandShell.  However, I'm having trouble figuring
out which aspects of the overall (and impressive) Unix-oriented behaviour
are supposedly available for Windows platforms.  On the OSProcess web page
it just says "The Windows support is not as complete as that for Unix, but
it is sufficient for running external Win32 programs from Squeak."

Ideally what I'd like to do is launch an executable (a Java application,
typically invoked through a batch file) that listens for user-typed
commands on stdin, and produces console-style responses.  I'd like to
throw commands at it from Squeak, listen for the corresponding results,
then eventually shut it down.

However, as things are:

 - CommandShell will happily start a command, but only if it includes
redirections for both stdout and stderr.  Otherwise I get walkbacks from
two BufferedAsyncFileReadStream instances, which find themselves unable
to run primTestEndOfFileFlag:

 - Even if I do provide stdout and stderr redirections, they don't
actually receive any output from the running process.

So - is it that ExternalPipes are (for now) completely unsupported for
Windows?  Or have I just managed to mess things up somewhere?

If they're not available, I'm hoping I can hack something up using a
Unix-style "tail" command to deliver the input, or some such scheme.  That
was the plan before I found these packages.


Thanks -

Aran
--
Aran Lunzer
Hokkaido University, Japan

Hi,

> Ideally what I'd like to do is launch an executable (a Java application,
> typically invoked through a batch file) that listens for user-typed
> commands on stdin, and produces console-style responses.  I'd like to
> throw commands at it from Squeak, listen for the corresponding results,
> then eventually shut it down.

You might try the ProcessWrapper package.
We tried it with the image and vm in
http://ftp.squeak.org/3.7/win/Squeak3.7-current-win-full.zip on vista.
You can use it like:

p := ProcessWrapper new
    useStdout;
    startWithShellCommand: 'cat';
    yourself.
p writeToStdin: 'foo'.
(p next: 3) = 'foo'

It's available here: http://www.squeaksource.com/ProcessWrapper.html

Cheers, Balázs

Hello Bal�D+!zs - thanks for the pointer!

So... I tried installing it, but none of my 3.7 images (on XP or on Vista)
could work with the ready-built DLL.  Not even the out-of-the-box 3.7
release.  The 3.9 release image seemed much happier: the precise example
you gave here didn't work as I was expecting, but the basic example on the
SqueakSource summary page did:

  ProcessWrapper new
    useStdout;
    startWithShellCommand: 'echo hello';
    upToEnd

  -->  'hello<cr>'


Looking at the source code for the DLL, I'm afraid that at the level of my
non-Squeak skills it would probably take me a day to rebuild it.  Do you
happen to have a 3.7-specific compiled DLL?

Many thanks

Aran

Aran Lunzer wrote:
> Looking at the source code for the DLL, I'm afraid that at the level of my
> non-Squeak skills it would probably take me a day to rebuild it.  Do you
> happen to have a 3.7-specific compiled DLL?

It is extremely unlikely that the problem is with the DLL. More likely
you are switching between VMs that are not compatible with this version.
Try running your 3.7 images with a more recent VM and see if this works
with the DLL in question.

Cheers,
  - Andreas

Hi!

To make sure that the given example works as expected, you have to make
sure that cat (cat.exe) is in the vm's search path, or you have to use
the explicit path to the executable, like here:

p := ProcessWrapper new
         useStdout;
         startWithCommand: 'C:\UnxUtils\usr\local\wbin\cat.exe';
         yourself.
p writeToStdin: 'foo'.
self assert: (p next: 3) = 'foo'.
p closeStdin.

If you don't have cat.exe (because windows doesn't have it by default),
you can download the unxutils package which contains it from:
http://unxutils.sourceforge.net/

If you have cat.exe and touch.exe in the vm's search path, then you can
run the tests in the package which should all be green.

Cheers,
Levente

On Tue, Mar 24, 2009 at 11:54:11PM +0900, Aran Lunzer wrote:
>
> So - is it that ExternalPipes are (for now) completely unsupported for
> Windows?  Or have I just managed to mess things up somewhere?

Aran,

Yes, this is exactly the case. OSProcess (hence CommandShell) currently
has support for OS pipes on unix and Mac OS X, but not for Windows.

Sorry for my late reply; I have been away on holiday and have been
carefully avoiding anything resembling a computer or cell phone ;)

Dave