=pod

=head1 Migrating from Swish-e to Swish3

If you haven't already, read the L<Introduction to Swish3|swish_intro.7>
document first.

This document is intended for users already familiar with Swish-e
version 2.x who want to migrate to using Swish3.

=head2 The Tool Chain

Swish3 is intended to be one part of a search system tool chain.
In this section we will look at how Swish-e implements each of the tool
chain features, and then compare it to Swish3.

=head3 Aggregator

Swish-e has two built-in aggregators, for filesystem and web,
indicated with the B<-S> flag to the B<swish-e> command. Swish-e also
has a third B<-S> option called B<prog>, which is short for C<program>.
The C<program> is an aggregator that you define. Swish-e ships with several
example aggregators, including a filesystem crawler called B<DirTree.pl>
and a web crawler called B<spider.pl>. There are also example aggregators
for pulling data from a database and for specific kinds of documents, like
Hypermail mail archives.

Swish3 has no built-in aggregators. Instead, Swish3 takes the B<-S prog> approach
of defining an API for external aggregators to follow.

=head3 Normalizer

Swish-e has a feature called B<FileFilter> which allows you define an external
program to call if a document's name matches a particular pattern. The
file is handed to the external program and the output of the external program
is treated as the contents of the document. For example, you can specify
that all documents that end with C<.pdf> are first filtered through
the B<pdftotext> command.

Swish-e also comes with a set of Perl modules bundled together as
B<SWISH::Filter>. SWISH::Filter is used by the external aggregators like
B<DirTree.pl> and B<spider.pl>, thus making those programs both aggregators
and normalizers.

Swish3 has no built-in normalizer or feature like B<FileFilter>. Instead,
Swish3 assumes that something like SWISH::Filter will be used to standardize
documents before they are handed to Swish3.


=head2 Configuration

One of the biggest changes is the configuration file format. Swish3 uses
XML-style configuration files, and supports a subset of the configuration
options available in Swish-e.

This section documents the configuration options supported in Swish3.

=head2 See Also

=over

=item

L<Introduction to Swish3|swish_intro.7>

=item

L<Perl implementation of Swish3|SWISH::Prog>

=item

L<libswish3 API|libswish3.3>

=back