I have recently released Remote::Use at CPAN, which addresses the problem of loading modules from a binary compatible Perl Module Server. It is in partially in debt with this node and idsfa comment.

There was an actual motivation to have - as idsfa remarks - a solution that does not install the module (as Module::AutoINC), but one that only requires limited knowledge and no privileges.

At the institution I work the student laboratories contain hundreds of computers that can be started in Linux or Windows. The OS is replicated from a master copy in a server.
The administrators are reluctant to install all the Perl Modules I need for teaching. The problem is that I keep discovering interesting new modules and introducing them in my lectures, which means I am continuously bothering them, asking for a new module to be introduced in the master copy/computer.
However, I can still install that modules in a machine that is accesible to the students.

Remote::Use helps to solve these sort of problems. It provides ways to run a Perl program even if some libraries aren't availables at start time. The libraries will be downloaded from a specified server using a specified application that runs on top of some protocol. The clients must be binary compatibles with the server if binary libraries - See Remote::Use::Tutorial for examples - are involved. Typical downloaders are "Rsync" and "Wget" but any suitable alternative like lwp-mirror or "CURL" can be used. This means that many different protocols can be used for the transference: SSH, SFTP, HTTP, HTTPS, FTP, etc. This way, my students can download the modules their programs use to a scratch directory. Once the modules are downloaded they will not be downloaded again, unless the modules are removed from the scratch disk.

Read Remote::Use::Tutorial if you want to know more.

The way to make it work is simple. Consider the following program:

$ cat -n prime3.pl
   1  #!/usr/bin/perl -I../lib -w
   2  # The module Math::Prime::XS isn't installed in the machine
   3  # but will be downloaded from some remote server
   4  use Math::Prime::XS qw{:all};
   5
   6  @all_primes   = primes(9);
   7  print "@all_primes\n";
   8
   9  @range_primes = primes(4, 9);
  10  print "@range_primes\n";
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The client machine does not have installed Math::Prime::XS. As the name suggest, the modules involves some binary libraries. By declaring the use of Remote::Use first, the libraries will be downloaded and the program can complete its execution:

 $ time perl -MRemote::Use=config,rsyncconfig prime3.pl
  receiving file list ... done
  >f+++++++++ XS.so

  sent 42 bytes  received 16141 bytes  10788.67 bytes/sec
  total size is 16043  speedup is 0.99
  receiving file list ... done
  >f+++++++++ XS.bs

  sent 42 bytes  received 94 bytes  90.67 bytes/sec
  total size is 0  speedup is 0.00
  receiving file list ... done
  >f+++++++++ XS.pm

  sent 42 bytes  received 5733 bytes  11550.00 bytes/sec
  total size is 5635  speedup is 0.98
  2 3 5 7
  5 7

  real    0m2.349s
  user    0m0.116s
  sys     0m0.060s
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The libraries are stored in a cache directory. consequently succesive executions don't pay extra overhead:

  $ time perl -MRemote::Use=config,rsyncconfig prime3.pl
  2 3 5 7
  5 7

  real    0m0.066s
  user    0m0.056s
  sys     0m0.008s
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The programmer has however to set a configuration file rsyncconfig setting the parameters that govern the downloading process:

$ cat rsyncconfig
package rsyncconfig;

sub getarg {
  my ($class, $self) = @_;

  return (
    host => 'orion:',
    prefix => '/tmp/perl5lib/',
    command => 'rsync -i -vaue ssh',
    ppmdf => '/tmp/perl5lib/.orion.installed.modules',
  );
}

1;
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Casiano

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