Graph::Easy - Manual

This chapter explains possible error messages, especially these from the Mediawiki integration.

• Error #1 - Cannot execute graphcnv
• Error #2 - Parser error
• Error #3 - Invalid output format
• Error #4 - Cannot write file
• Error #5 - Cannot execute dot
• Error #6 - Timeout in layout

The program graphcnv couldn't be executed, either because it was not found, or does not have execution permission. Check first that you can run it manually from your MediaWiki directory (e.g. /srv/www/htdocs/wiki/):

perl graph/graphcnv '[ Bonn ] -> [ Berlin ]' 'ascii'

This should result in similiar output like this:

<pre>
+------+     +--------+
| Bonn | --> | Berlin |
+------+     +--------+

<pre>

If you get an error message, check the permissions of graphcnv and make sure it is executable by the user your webserver runs under.

The graph code you did write is invalid, or the parser did not understand it. Usually this means you made a typo in an attribute name, forgot a closing ] or similiar mistakes.
If the code you wrote is correct, but the parser still does not parse it properly, please file a bugreport.

If you are unsure what attributes you can use and what their format is, have a look at the attribute definitions.

graphcnv understands the following output formats:

• graphviz
• svg
• html
• ascii
• boxart

To what exact format the graphviz format is rendered is set in the config file graph.cfg. The user cannot change this from inside the graph code. This means that all files generated via graphviz are in the same format, f.i. png.

graphcnv could not write the file. Please make sure that the output directory is properly configured in graph.cfg, exists and is writable by your web server process. You might need to set the user and group of this directory to whatever your web server runs under.

To create png graphics, the graphcnv program uses dot or any other graphviz program like neato or circo. Which program is uses exactly is defined in the config file graph.cfg.
You need to install the graphviz package, and the program to be used must be in your path, like /usr/bin/dot or /usr/local/bin/dot.

The layouter in Graph::Easy sometimes cannot complete the layout. To prevent it getting stuck in an endless loop, there is a hard time limit of 5 seconds, after that the layout stage will be aborted.
If the server is under heavy load, the conversion of the graph might be aborted even though the layouter would have been able to complete the layout. In this case, you might try again.
If the layout still does not finish, try as output format graphviz. In addition, please file a bugreport so that I can improve my code.

Graph::Easy can handle small to medium sized graphs, but on more complicated graphs it has problems like missing edges, nodes or that the layout takes quite a bit of time.

Contact and Bugreports

If you have questions, feel free to send me an email (Gnupg key). Bugreports should go to rt.cpan.org.