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Ace/Local.pm  view on Meta::CPAN

Ace::Local - use giface, tace or gifaceclient to open a local connection to an Ace database

=head1 SYNOPSIS

  use Ace::Local
  my $ace = Ace::Local->connect(-path=>'/usr/local/acedb/elegans');
  $ace->query('find author Se*');
  die "Query unsuccessful" unless $ace->status;
  $ace->query('show');
  while ($ace->encore) {
    print $ace->read;
  }

=head1 DESCRIPTION

This class is provided for low-level access to local (non-networked)
Ace databases via the I<giface> program.  You will generally not need
to access it directly.  Use Ace.pm instead.

For the sake of completeness, the method can also use the I<aceclient>
program for its access.  However the Ace::AceDB class is more efficient
for this purpose.

=head1 METHODS

=head2 connect()

  $accessor = Ace::Local->connect(-path=>$path_to_database);

Connect to the database at the indicated path using I<giface> and
return a connection object (an "accessor").  I<Giface> must be on the
current search path.  Multiple accessors may be open simultaneously.

Arguments include:

=over 4

=item B<-path>

Path to the database (location of the "wspec/" directory).

=item B<-program>

Used to indicate the location of the desired I<giface> or
I<gifaceclient> executable.  You may also use I<tace> or I<aceclient>,
but in that case the asGIF() functionality will nog work.  Can be used
to override the search path.

=item B<-host>

Used when invoking I<gifaceclient>.  Indicates the host to connect to.

=item B<-port>

Used when invoking I<gifaceclient>.  Indicates the port to connect to.

=item B<-nosync>

Ordinarily Ace::Local synchronizes with the tace/giface prompt,
throwing out all warnings and copyright messages.  If this is set,
Ace::Local will not do so.  In this case you must call the low_read()
method until it returns undef in order to synchronize.

=back

=head2 query()

  $status = $accessor->query('query string');

Send the query string to the server and return a true value if
successful.  You must then call read() repeatedly in order to fetch
the query result.

=head2 read()

Read the result from the last query sent to the server and return it
as a string.  ACE may return the result in pieces, breaking between
whole objects.  You may need to read repeatedly in order to fetch the
entire result.  Canonical example:

  $accessor->query("find Sequence D*");
  die "Got an error ",$accessor->error() if $accessor->status == STATUS_ERROR;
  while ($accessor->status == STATUS_PENDING) {
     $result .= $accessor->read;
  }

=head2 low_read()

Read whatever data's available, or undef if none.  This is only used
by the ace.pl replacement for giface/tace.

=head2 status()

Return the status code from the last operation.  Status codes are
exported by default when you B<use> Ace.pm.  The status codes you may
see are:

  STATUS_WAITING    The server is waiting for a query.
  STATUS_PENDING    A query has been sent and Ace is waiting for
                    you to read() the result.
  STATUS_ERROR      A communications or syntax error has occurred

=head2 error()

May return a more detailed error code supplied by Ace.  Error checking
is not fully implemented.

=head2 encore()

This method will return true after you have performed one or more
read() operations, and indicates that there is more data to read.
B<encore()> is functionally equivalent to:

   $encore = $accessor->status == STATUS_PENDING;

In fact, this is how it's implemented.

=head2 auto_save()

Sets or queries the I<auto_save> variable.  If true, the "save"