=head1 NAME

Client_A-Gateway - Perl5 program to act as a gateway between the AS/400 system at Client_A and the Client_B database.

=head1 SYNOPSIS

B<Client_A-incoming>
[ B<-config_file>|B<-cf> I<path> ]
[ B<-ftp_root>|B<-fr> I<path> ]
[ B<-work_root>|B<-wr> I<path> ]
[ B<-clientb_root>|B<-sr> I<path> ]
[ B<-incoming_dir>|B<-id> I<path> ]
[ B<-incoming_archive>|B<-ia> I<path> ]
[ B<-outgoing_dir>|B<-od> I<path> ]
[ B<-outgoing_archive>|B<-oa> I<path> ]
[ B<-shop_number>|B<-sn> I<number> ]
[ B<-logging> ]
[ B<-nologging> ]
[ B<-log_file>|B<-lf> I<path> ]
[ B<-archive> ]
[ B<-noarchive> ]
[ B<-in_keep_days>|B<-ikd> I<days> ]
[ B<-out_keep_days>|B<-okd> I<days> ]

B<Client_A-outgoing>
[ options as above ]

B<Client_A-archive>
[ options as above ]

=head1 OVERVIEW

The Client_A-gateway program processes incoming and outgoing data files from/to the AS/400 system at Client_A
and Client_B.

Client_A had already developed an interface to exchange data with their Store systems, so are using the
same interface (albeit with different data) to talk to Client_B.  This program emulates the
behaviour expected by the AS/400 system at the Store.

It can be invoked in one of 3 ways, each method involving the use of a symbolic link to the actual
program.

=over 4

=item Client_A-incoming

Processes incoming data files, checking that the batch received has not already been received before,
and that the accompanying control record matches the batch.  The process I<will> process a batch it
has seen before, but only if it has more records than the original (and then it only processes the
new records).  On completion a confirmation record is written to the incoming ftp directory for the
AS/400 to pickup.

=item Client_A-outgoing

Picks up data waiting to go to Client_A from Client_B, packages it in a format expected by the AS/400,
puts it into the outgoing ftp directory, and then updates the control file in the outgoing ftp directory.
The control file is used by the AS/400 to find out what batches are available.  It is trimmed by the
Client_A-archive invocation to hold no more than 7 days worth of control records.

=item Client_A-archive

If archiving is turned on, the Client_A-incoming and Client_A-outgoing processes will put a copy of the data file
into the relevant archive directory.  These archives are then removed by Client_A-archive once they become
too old.  This process also trims the outgoing ftp directory of outgoing data batches which are more than
7 days old, and updates the outgoing control file.

=back

=cut