use SOAP::Lite;
use SOAP::Data qw/name/;

my $soap = new SOAP::Lite(
  uri => 'urn:sap-com:document:sap:rfc:functions',
  proxy => 'http://wherever.it.lives.example'
);

my $som = $soap->SAP_WAPI_START_WORKFLOW(
  name(TASK => $wf_task),
  name(USER => $wf_user)
);
die $som->faultdetail if ($som->fault);

say $som->result;