NAME
    Graph::XGMML - Simple Graph.pm-like interface for generating XGMML
    graphs

SYNOPSIS
      use Graph::XGMML;
      
  my $output = '';
      my $graph  = Graph::XGMML->new(
          directed => 1,
          OUTPUT   => \$output,
      );
      $graph->add_node('foo');
      $graph->add_node('bar');
      $graph->add_edge('foo', 'bar');
      $graph->end;

DESCRIPTION
    To produce useful diagrams on extremely large graphs, sometimes it is
    necesary to move beyond simple graphing tools to applications
    specifically designed for rendering very large graphs, many of which
    were designed for biology applications (such as my favourite Cytoscape).

    Graph::XGMML is a module that can be used to generate export files for
    arbitrarily large graphs in eXtensible Graph Modelling Markup Language,
    so that the graphs can be imported into these specialised tools.

    The API is intentionally designed to appear similar to more popular
    modules such as Graph, Graph::Easy and GraphViz.

METHODS
  new
      # Quick constructor to write to a file
      $graph  = Graph::XGMML->new(
          directed => 1,
          OUTPUT   => IO::File->new('file', 'w'),
      );
      
  # Anonymous constructor
      $graph = Graph::XGMML->new(
          directed => 1,
      );

    The "new" constructor is used to create a graph writer.

    It takes a single optional boolean "directed" parameter, which indicates
    if the graphs you will be generating will be directed or undirected.

    If any additional parameters are passed to "new", the constructor will
    make an additional call to the "start" method to start writing the
    document header and to open the root "graph" node, passing it the extra
    parameters.

    Returns a new Graph::XGMML object, or throws an exception (dies) on
    error.

  start
    The "start" method allows you to explicitly start the document writing,
    if the original constructor was produced without additional parameters.

    Any parameters are passed directly to the underlying XML::Writer
    constructor which produces the object that will be used to generate the
    XML.

    Returns true if the document is started successfully, or throws an
    exception (dies) on error.

  add_node
      # Add a simple node
      $graph->add_node( 'name' );
      
  # Add optional tag attributes
      $graph->add_node( 'name',
          label  => 'Tag Label',
          weight => 100,
      );

    The "add_node" method is used to add a new node to the graph.

    Because the Graph::XGMML object doesn't remember its state as it
    produces the graph, you must specify all nodes in the graph explicitly.

    The first parameter is the identifier for the node. Any additional
    parameters will be treated XGMML "node" element tag pairs.

    Returns true or throws an exception (dies) on error.

  add_vertex
    The "add_vertex" method is an alias to "add_node", provided for
    increased compatibility with the Graph API.

    It takes the same parameters as "add_node".

  add_edge
      # Add a simple edge
      $graph->add_edge( 'foo' => 'bar' );
      
  # Add with optional attributes
      $graph->add_edge( 'foo' => 'bar',
          weight => 1,
      );

    The c<add_edge> method adds an edge to the graph.

    The first two parameters are the source and target of the edge. Any
    additional parameters should be a set of key/value pairs of edge
    attributes.

    Returns true or throws an exception (dies) on error.

  end
      # Explicitly terminate the document
      $graph->end;

    The "end" method is used to indicate that the graph is completed that
    the XML should be terminated.

    If you do not call it yourself, it will be called for you at
    "DESTROY"-time.

SUPPORT
    Bugs should always be submitted via the CPAN bug tracker

    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Graph-XGMML>

    For other issues, contact the maintainer.

AUTHOR
    Adam Kennedy <adamk@cpan.org>

SEE ALSO
    Graph, Graph::Easy, GraphViz

COPYRIGHT
    Copyright 2009 Adam Kennedy.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

    The full text of the license can be found in the LICENSE file included
    with this module.